Network Working Group K. McCloghrie
Request for Comments: 2863 Cisco Systems
Obsoletes: 2233 F. Kastenholz
Category: Standards Track Argon Networks
June 2000
The Interfaces Group MIB
Status of this Memo
This document specifies an Internet standards track protocol for the
Internet community, and requests discussion and suggestions for
improvements. Please refer to the current edition of the "Internet
Official Protocol Standards" (STD 1) for the standardization state
and status of this protocol. Distribution of this memo is unlimited.
Copyright Notice
Copyright (C) The Internet Society (2000). All Rights Reserved.
Table of Contents
1 Introduction ................................................. 2
2 The SNMP Network Management Framework ........................ 2
3 Experience with the Interfaces Group ......................... 3
3.1 Clarifications/Revisions ................................... 4
3.1.1 Interface Sub-Layers ..................................... 4
3.1.2 Guidance on Defining Sub-layers .......................... 7
3.1.3 Virtual Circuits ......................................... 8
3.1.4 Bit, Character, and Fixed-Length Interfaces .............. 8
3.1.5 Interface Numbering ...................................... 10
3.1.6 Counter Size ............................................. 14
3.1.7 Interface Speed .......................................... 16
3.1.8 Multicast/Broadcast Counters ............................. 17
3.1.9 Trap Enable .............................................. 17
3.1.10 Addition of New ifType values ........................... 18
3.1.11 InterfaceIndex Textual Convention ....................... 18
3.1.12 New states for IfOperStatus ............................. 18
3.1.13 IfAdminStatus and IfOperStatus .......................... 19
3.1.14 IfOperStatus in an Interface Stack ...................... 21
3.1.15 Traps ................................................... 21
3.1.16 ifSpecific .............................................. 23
3.1.17 Creation/Deletion of Interfaces ......................... 23
3.1.18 All Values Must be Known ................................ 24
4 Media-Specific MIB Applicability ............................. 24
5 Overview ..................................................... 25
6 Interfaces Group Definitions ................................. 26
McCloghrie & Kastenholz Standards Track [Page 1]
RFC 2863 The Interfaces Group MIB June 2000
7 Acknowledgements ............................................. 64
8 References ................................................... 64
9 Security Considerations ...................................... 66
10 Authors' Addresses .......................................... 67
11 Changes from RFC 2233 ....................................... 67
12 Notice on Intellectual Property ............................. 68
13 Full Copyright Statement .................................... 69
1. Introduction
This memo defines a portion of the Management Information Base (MIB)
for use with network management protocols in the Internet community.
In particular, it describes managed objects used for managing Network
Interfaces. This memo discusses the 'interfaces' group of MIB-II
[17], especially the experience gained from the definition of
numerous media-specific MIB modules for use in conjunction with the '
interfaces' group for managing various sub-layers beneath the
internetwork-layer. It specifies clarifications to, and extensions
of, the architectural issues within the MIB-II model of the '
interfaces' group. This memo obsoletes RFC 2233, the previous
version of the Interfaces Group MIB.
The key words "MUST" and "MUST NOT" in this document are to be
interpreted as described in RFC 2119 [16].
2. The SNMP Network Management Framework
The SNMP Management Framework presently consists of five major
components:
o An overall architecture, described in RFC 2571 [1].
o Mechanisms for describing and naming objects and events for the
purpose of management. The first version of this Structure of
Management Information (SMI) is called SMIv1 and described in
STD 16, RFC 1155 [2], STD 16, RFC 1212 [3] and RFC 1215 [4].
The second version, called SMIv2, is described in STD 58, which
consists of RFC 2578 [5], RFC 2579 [6] and RFC 2580 [7].
o Message protocols for transferring management information. The
first version of the SNMP message protocol is called SNMPv1 and
described in STD 15, RFC 1157 [8]. A second version of the
SNMP message protocol, which is not an Internet standards track
protocol, is called SNMPv2c and described in RFC 1901 [9] and
RFC 1906 [10]. The third version of the message protocol is
called SNMPv3 and described in RFC 1906 [10], RFC 2572 [11] and
RFC 2574 [12].
McCloghrie & Kastenholz Standards Track [Page 2]
RFC 2863 The Interfaces Group MIB June 2000
o Protocol operations for accessing management information. The
first set of protocol operations and associated PDU formats is
described in STD 15, RFC 1157 [8]. A second set of protocol
operations and associated PDU formats is described in RFC 1905
[13].
o A set of fundamental applications described in RFC 2573 [14]
and the view-based access control mechanism described in RFC
2575 [15].
A more detailed introduction to the current SNMP Management Framework
can be found in RFC 2570 [22].
Managed objects are accessed via a virtual information store, termed
the Management Information Base or MIB. Objects in the MIB are
defined using the mechanisms defined in the SMI.
This memo specifies a MIB module that is compliant to the SMIv2. A
MIB conforming to the SMIv1 can be produced through the appropriate
translations. The resulting translated MIB must be semantically
equivalent, except where objects or events are omitted because no
translation is possible (e.g., use of Counter64). Some machine
readable information in SMIv2 will be converted into textual
descriptions in SMIv1 during the translation process. However, this
loss of machine readable information is not considered to change the
semantics of the MIB.
3. Experience with the Interfaces Group
One of the strengths of internetwork-layer protocols such as IP [18]
is that they are designed to run over any network interface. In
achieving this, IP considers any and all protocols it runs over as a
single "network interface" layer. A similar view is taken by other
internetwork-layer protocols. This concept is represented in MIB-II
by the 'interfaces' group which defines a generic set of managed
objects such that any network interface can be managed in an
interface-independent manner through these managed objects. The '
interfaces' group provides the means for additional managed objects
specific to particular types of network interface (e.g., a specific
medium such as Ethernet) to be defined as extensions to the '
interfaces' group for media-specific management. Since the
standardization of MIB-II, many such media-specific MIB modules have
been defined.
Experience in defining these media-specific MIB modules has shown
that the model defined by MIB-II is too simplistic and/or static for
some types of media-specific management. As a result, some of these
media-specific MIB modules assume an evolution or loosening of the
McCloghrie & Kastenholz Standards Track [Page 3]
RFC 2863 The Interfaces Group MIB June 2000
model. This memo documents and standardizes that evolution of the
model and fills in the gaps caused by that evolution. This memo also
incorporates the interfaces group extensions documented in RFC 1229
[19].
3.1. Clarifications/Revisions
There are several areas for which experience has indicated that
clarification, revision, or extension of the model would be helpful.
The following sections discuss the changes in the interfaces group
adopted by this memo in each of these areas.
In some sections, one or more paragraphs contain discussion of
rejected alternatives to the model adopted in this memo. Readers not
familiar with the MIB-II model and not interested in the rationale
behind the new model may want to skip these paragraphs.
3.1.1. Interface Sub-Layers
Experience in defining media-specific management information has
shown the need to distinguish between the multiple sub-layers beneath
the internetwork-layer. In addition, there is a need to manage these
sub-layers in devices (e.g., MAC-layer bridges) which are unaware of
which, if any, internetwork protocols run over these sub-layers. As
such, a model of having a single conceptual row in the interfaces
table (MIB-II's ifTable) represent a whole interface underneath the
internetwork-layer, and having a single associated media-specific MIB
module (referenced via the ifType object) is too simplistic. A
further problem arises with the value of the ifType object which has
enumerated values for each type of interface.
Consider, for example, an interface with PPP running over an HDLC
link which uses a RS232-like connector. Each of these sub-layers has
its own media-specific MIB module. If all of this is represented by
a single conceptual row in the ifTable, then an enumerated value for
ifType is needed for that specific combination which maps to the
specific combination of media-specific MIBs. Furthermore, such a
model still lacks a method to describe the relationship of all the
sub-layers of the MIB stack.
An associated problem is that of upward and downward multiplexing of
the sub-layers. An example of upward multiplexing is MLP (Multi-
Link-Procedure) which provides load-sharing over several serial lines
by appearing as a single point-to-point link to the sub-layer(s)
above. An example of downward multiplexing would be several
instances of PPP, each framed within a separate X.25 virtual circuit,
McCloghrie & Kastenholz Standards Track [Page 4]
RFC 2863 The Interfaces Group MIB June 2000
all of which run over one fractional T1 channel, concurrently with
other uses of the T1 link. The MIB structure must allow these sorts
of relationships to be described.
Several solutions for representing multiple sub-layers were rejected.
One was to retain the concept of one conceptual row for all the sub-
layers of an interface and have each media-specific MIB module
identify its "superior" and "subordinate" sub-layers through OBJECT
IDENTIFIER "pointers". This scheme would have several drawbacks: the
superior/subordinate pointers would be contained in the media-
specific MIB modules; thus, a manager could not learn the structure
of an interface without inspecting multiple pointers in different MIB
modules; this would be overly complex and only possible if the
manager had knowledge of all the relevant media-specific MIB modules;
MIB modules would all need to be retrofitted with these new
"pointers"; this scheme would not adequately address the problem of
upward and downward multiplexing; and finally, enumerated values of
ifType would be needed for each combination of sub-layers. Another
rejected solution also retained the concept of one conceptual row for
all the sub-layers of an interface but had a new separate MIB table
to identify the "superior" and "subordinate" sub-layers and to
contain OBJECT IDENTIFIER "pointers" to the media-specific MIB module
for each sub-layer. Effectively, one conceptual row in the ifTable
would represent each combination of sub-layers between the
internetwork-layer and the wire. While this scheme has fewer
drawbacks, it still would not support downward multiplexing, such as
PPP over MLP: observe that MLP makes two (or more) serial lines
appear to the layers above as a single physical interface, and thus
PPP over MLP should appear to the internetwork-layer as a single
interface; in contrast, this scheme would result in two (or more)
conceptual rows in the ifTable, both of which the internetwork-layer
would run over. This scheme would also require enumerated values of
ifType for each combination of sub-layers.
The solution adopted by this memo is to have an individual conceptual
row in the ifTable to represent each sub-layer, and have a new
separate MIB table (the ifStackTable, see section 6 below) to
identify the "superior" and "subordinate" sub-layers through INTEGER
"pointers" to the appropriate conceptual rows in the ifTable. This
solution supports both upward and downward multiplexing, allows the
IANAifType to Media-Specific MIB mapping to identify the media-
specific MIB module for that sub-layer, such that the new table need
only be referenced to obtain information about layering, and it only
requires enumerated values of ifType for each sub-layer, not for
combinations of them. However, it does require that the descriptions
of some objects in the ifTable (specifically, ifType, ifPhysAddress,
ifInUcastPkts, and ifOutUcastPkts) be generalized so as to apply to
any sub-layer (rather than only to a sub-layer immediately beneath
McCloghrie & Kastenholz Standards Track [Page 5]
RFC 2863 The Interfaces Group MIB June 2000
the network layer as previously), plus some (specifically, ifSpeed)
which need to have appropriate values identified for use when a
generalized definition does not apply to a particular sub-layer.
In addition, this adopted solution makes no requirement that a
device, in which a sub-layer is instrumented by a conceptual row of
the ifTable, be aware of whether an internetwork protocol runs on top
of (i.e., at some layer above) that sub-layer. In fact, the counters
of packets received on an interface are defined as counting the
number "delivered to a higher-layer protocol". This meaning of
"higher-layer" includes:
(1) Delivery to a forwarding module which accepts
packets/frames/octets and forwards them on at the same protocol
layer. For example, for the purposes of this definition, the
forwarding module of a MAC-layer bridge is considered as a
"higher-layer" to the MAC-layer of each port on the bridge.
(2) Delivery to a higher sub-layer within a interface stack. For
example, for the purposes of this definition, if a PPP module
operated directly over a serial interface, the PPP module would
be considered the higher sub-layer to the serial interface.
(3) Delivery to a higher protocol layer which does not do packet
forwarding for sub-layers that are "at the top of" the
interface stack. For example, for the purposes of this
definition, the local IP module would be considered the higher
layer to a SLIP serial interface.
Similarly, for output, the counters of packets transmitted out an
interface are defined as counting the number "that higher-level
protocols requested to be transmitted". This meaning of "higher-
layer" includes:
(1) A forwarding module, at the same protocol layer, which
transmits packets/frames/octets that were received on an
different interface. For example, for the purposes of this
definition, the forwarding module of a MAC-layer bridge is
considered as a "higher-layer" to the MAC-layer of each port on
the bridge.
(2) The next higher sub-layer within an interface stack. For
example, for the purposes of this definition, if a PPP module
operated directly over a serial interface, the PPP module would
be a "higher layer" to the serial interface.
McCloghrie & Kastenholz Standards Track [Page 6]
RFC 2863 The Interfaces Group MIB June 2000
(3) For sub-layers that are "at the top of" the interface stack, a
higher element in the network protocol stack. For example, for
the purposes of this definition, the local IP module would be
considered the higher layer to an Ethernet interface.
3.1.2. Guidance on Defining Sub-layers
The designer of a media-specific MIB must decide whether to divide
the interface into sub-layers or not, and if so, how to make the
divisions. The following guidance is offered to assist the media-
specific MIB designer in these decisions.
In general, the number of entries in the ifTable should be kept to
the minimum required for network management. In particular, a group
of related interfaces should be treated as a single interface with
one entry in the ifTable providing that:
(1) None of the group of interfaces performs multiplexing for any
other interface in the agent,
(2) There is a meaningful and useful way for all of the ifTable's
information (e.g., the counters, and the status variables), and
all of the ifTable's capabilities (e.g., write access to
ifAdminStatus), to apply to the group of interfaces as a whole.
Under these circumstances, there should be one entry in the ifTable
for such a group of interfaces, and any internal structure which
needs to be represented to network management should be captured in a
MIB module specific to the particular type of interface.
Note that application of bullet 2 above to the ifTable's ifType
object requires that there is a meaningful media-specific MIB and a
meaningful ifType value which apply to the group of interfaces as a
whole. For example, it is not appropriate to treat an HDLC sub-layer
and an RS-232 sub-layer as a single ifTable entry when the media-
specific MIBs and the ifType values for HDLC and RS-232 are separate
(rather than combined).
Subject to the above, it is appropriate to assign an ifIndex value to
any interface that can occur in an interface stack (in the
ifStackTable) where the bottom of the stack is a physical interface
(ifConnectorPresent has the value 'true') and there is a layer-3 or
other application that "points down" to the top of this stack. An
example of an application that points down to the top of the stack is
the Character MIB [21].
McCloghrie & Kastenholz Standards Track [Page 7]
RFC 2863 The Interfaces Group MIB June 2000
Note that the sub-layers of an interface on one device will sometimes
be different from the sub-layers of the interconnected interface of
another device; for example, for a frame-relay DTE interface
connected a frameRelayService interface, the inter-connected DTE and
DCE interfaces have different ifType values and media-specific MIBs.
These guidelines are just that, guidelines. The designer of a
media-specific MIB is free to lay out the MIB in whatever SMI
conformant manner is desired. However, in doing so, the media-
specific MIB MUST completely specify the sub-layering model used for
the MIB, and provide the assumptions, reasoning, and rationale used
to develop that model.
3.1.3. Virtual Circuits
Several of the sub-layers for which media-specific MIB modules have
been defined are connection oriented (e.g., Frame Relay, X.25).
Experience has shown that each effort to define such a MIB module
revisits the question of whether separate conceptual rows in the
ifTable are needed for each virtual circuit. Most, if not all, of
these efforts to date have decided to have all virtual circuits
reference a single conceptual row in the ifTable.
This memo strongly recommends that connection-oriented sub-layers do
not have a conceptual row in the ifTable for each virtual circuit.
This avoids the proliferation of conceptual rows, especially those
which have considerable redundant information. (Note, as a
comparison, that connection-less sub-layers do not have conceptual
rows for each remote address.) There may, however, be circumstances
under which it is appropriate for a virtual circuit of a connection-
oriented sub-layer to have its own conceptual row in the ifTable; an
example of this might be PPP over an X.25 virtual circuit. The MIB
in section 6 of this memo supports such circumstances.
If a media-specific MIB wishes to assign an entry in the ifTable to
each virtual circuit, the MIB designer must present the rationale for
this decision in the media-specific MIB's specification.
3.1.4. Bit, Character, and Fixed-Length Interfaces
RS-232 is an example of a character-oriented sub-layer over which
(e.g., through use of PPP) IP datagrams can be sent. Due to the
packet-based nature of many of the objects in the ifTable, experience
has shown that it is not appropriate to have a character-oriented
sub-layer represented by a whole conceptual row in the ifTable.
McCloghrie & Kastenholz Standards Track [Page 8]
RFC 2863 The Interfaces Group MIB June 2000
Experience has also shown that it is sometimes desirable to have some
management information for bit-oriented interfaces, which are
similarly difficult to represent by a whole conceptual row in the
ifTable. For example, to manage the channels of a DS1 circuit, where
only some of the channels are carrying packet-based data.
A further complication is that some subnetwork technologies transmit
data in fixed length transmission units. One example of such a
technology is cell relay, and in particular Asynchronous Transfer
Mode (ATM), which transmits data in fixed-length cells. Representing
such a interface as a packet-based interface produces redundant
objects if the relationship between the number of packets and the
number of octets in either direction is fixed by the size of the
transmission unit (e.g., the size of a cell).
About half the objects in the ifTable are applicable to every type of
interface: packet-oriented, character-oriented, and bit-oriented. Of
the other half, two are applicable to both character-oriented and
packet-oriented interfaces, and the rest are applicable only to
packet-oriented interfaces. Thus, while it is desirable for
consistency to be able to represent any/all types of interfaces in
the ifTable, it is not possible to implement the full ifTable for
bit- and character-oriented sub-layers.
A rejected solution to this problem would be to split the ifTable
into two (or more) new MIB tables, one of which would contain objects
that are relevant only to packet-oriented interfaces (e.g., PPP), and
another that may be used by all interfaces. This is highly
undesirable since it would require changes in every agent
implementing the ifTable (i.e., just about every existing SNMP
agent).
The solution adopted in this memo builds upon the fact that
compliance statements in SMIv2 (in contrast to SMIv1) refer to object
groups, where object groups are explicitly defined by listing the
objects they contain. Thus, with SMIv2, multiple compliance
statements can be specified, one for all interfaces and additional
ones for specific types of interfaces. The separate compliance
statements can be based on separate object groups, where the object
group for all interfaces can contain only those objects from the
ifTable which are appropriate for every type of interfaces. Using
this solution, every sub-layer can have its own conceptual row in the
ifTable.
Thus, section 6 of this memo contains definitions of the objects of
the existing 'interfaces' group of MIB-II, in a manner which is both
SNMPv2-compliant and semantically-equivalent to the existing MIB-II
definitions. With equivalent semantics, and with the BER ("on the
McCloghrie & Kastenholz Standards Track [Page 9]
RFC 2863 The Interfaces Group MIB June 2000
wire") encodings unchanged, these definitions retain the same OBJECT
IDENTIFIER values as assigned by MIB-II. Thus, in general, no
rewrite of existing agents which conform to MIB-II and the
ifExtensions MIB is required.
In addition, this memo defines several object groups for the purposes
of defining which objects apply to which types of interface:
(1) the ifGeneralInformationGroup. This group contains those
objects applicable to all types of network interfaces,
including bit-oriented interfaces.
(2) the ifPacketGroup. This group contains those objects
applicable to packet-oriented network interfaces.
(3) the ifFixedLengthGroup. This group contains the objects
applicable not only to character-oriented interfaces, such as
RS-232, but also to those subnetwork technologies, such as
cell-relay/ATM, which transmit data in fixed length
transmission units. As well as the octet counters, there are
also a few other counters (e.g., the error counters) which are
useful for this type of interface, but are currently defined as
being packet-oriented. To accommodate this, the definitions of
these counters are generalized to apply to character-oriented
interfaces and fixed-length-transmission interfaces.
It should be noted that the octet counters in the ifTable aggregate
octet counts for unicast and non-unicast packets into a single octet
counter per direction (received/transmitted). Thus, with the above
definition of fixed-length-transmission interfaces, where such
interfaces which support non-unicast packets, separate counts of
unicast and multicast/broadcast transmissions can only be maintained
in a media-specific MIB module.
3.1.5. Interface Numbering
MIB-II defines an object, ifNumber, whose value represents:
"The number of network interfaces (regardless of their
current state) present on this system."
Each interface is identified by a unique value of the ifIndex object,
and the description of ifIndex constrains its value as follows:
"Its value ranges between 1 and the value of ifNumber. The
value for each interface must remain constant at least from
one re-initialization of the entity's network management
system to the next re-initialization."
McCloghrie & Kastenholz Standards Track [Page 10]
RFC 2863 The Interfaces Group MIB June 2000
This constancy requirement on the value of ifIndex for a particular
interface is vital for efficient management. However, an increasing
number of devices allow for the dynamic addition/removal of network
interfaces. One example of this is a dynamic ability to configure
the use of SLIP/PPP over a character-oriented port. For such dynamic
additions/removals, the combination of the constancy requirement and
the restriction that the value of ifIndex is less than ifNumber is
problematic.
Redefining ifNumber to be the largest value of ifIndex was rejected
since it would not help. Such a re-definition would require ifNumber
to be deprecated and the utility of the redefined object would be
questionable. Alternatively, ifNumber could be deprecated and not
replaced. However, the deprecation of ifNumber would require a
change to that portion of ifIndex's definition which refers to
ifNumber. So, since the definition of ifIndex must be changed anyway
in order to solve the problem, changes to ifNumber do not benefit the
solution.
The solution adopted in this memo is just to delete the requirement
that the value of ifIndex must be less than the value of ifNumber,
and to retain ifNumber with its current definition. This is a minor
change in the semantics of ifIndex; however, all existing agent
implementations conform to this new definition, and in the interests
of not requiring changes to existing agent implementations and to the
many existing media-specific MIBs, this memo assumes that this change
does not require ifIndex to be deprecated. Experience indicates that
this assumption does "break" a few management applications, but this
is considered preferable to breaking all agent implementations.
This solution also results in the possibility of "holes" in the
ifTable, i.e., the ifIndex values of conceptual rows in the ifTable
are not necessarily contiguous, but SNMP's GetNext (and GetBulk)
operation easily deals with such holes. The value of ifNumber still
represents the number of conceptual rows, which increases/decreases
as new interfaces are dynamically added/removed.
The requirement for constancy (between re-initializations) of an
interface's ifIndex value is met by requiring that after an interface
is dynamically removed, its ifIndex value is not re-used by a
*different* dynamically added interface until after the following
re-initialization of the network management system. This avoids the
need for assignment (in advance) of ifIndex values for all possible
interfaces that might be added dynamically. The exact meaning of a
"different" interface is hard to define, and there will be gray
areas. Any firm definition in this document would likely turn out to
be inadequate. Instead, implementors must choose what it means in
their particular situation, subject to the following rules:
McCloghrie & Kastenholz Standards Track [Page 11]
RFC 2863 The Interfaces Group MIB June 2000
(1) a previously-unused value of ifIndex must be assigned to a
dynamically added interface if an agent has no knowledge of
whether the interface is the "same" or "different" to a
previously incarnated interface.
(2) a management station, not noticing that an interface has gone
away and another has come into existence, must not be confused
when calculating the difference between the counter values
retrieved on successive polls for a particular ifIndex value.
When the new interface is the same as an old interface, but a
discontinuity in the value of the interface's counters cannot be
avoided, the ifTable has (until now) required that a new ifIndex
value be assigned to the returning interface. That is, either all
counter values have had to be retained during the absence of an
interface in order to use the same ifIndex value on that interface's
return, or else a new ifIndex value has had to be assigned to the
returning interface. Both alternatives have proved to be burdensome
to some implementations:
(1) maintaining the counter values may not be possible (e.g., if
they are maintained on removable hardware),
(2) using a new ifIndex value presents extra work for management
applications. While the potential need for such extra work is
unavoidable on agent re-initializations, it is desirable to
avoid it between re-initializations.
To address this, a new object, ifCounterDiscontinuityTime, has been
defined to record the time of the last discontinuity in an
interface's counters. By monitoring the value of this new object, a
management application can now detect counter discontinuities without
the ifIndex value of the interface being changed. Thus, an agent
which implements this new object should, when a new interface is the
same as an old interface, retain that interface's ifIndex value and
update if necessary the interface's value of
ifCounterDiscontinuityTime. With this new object, a management
application must, when calculating differences between counter values
retrieved on successive polls, discard any calculated difference for
which the value of ifCounterDiscontinuityTime is different for the
two polls. (Note that this test must be performed in addition to the
normal checking of sysUpTime to detect an agent re-initialization.)
Since such discards are a waste of network management processing and
bandwidth, an agent should not update the value of
ifCounterDiscontinuityTime unless absolutely necessary.
While defining this new object is a change in the semantics of the
ifTable counter objects, it is impractical to deprecate and redefine
McCloghrie & Kastenholz Standards Track [Page 12]
RFC 2863 The Interfaces Group MIB June 2000
all these counters because of their wide deployment and importance.
Also, a survey of implementations indicates that many agents and
management applications do not correctly implement this aspect of the
current semantics (because of the burdensome issues mentioned above),
such that the practical implications of such a change is small.
Thus, this breach of the SMI's rules is considered to be acceptable.
Note, however, that the addition of ifCounterDiscontinuityTime does
not change the fact that:
it is necessary at certain times for the assignment of
ifIndex values to change on a re-initialization of the agent
(such as a reboot).
The possibility of ifIndex value re-assignment must be accommodated
by a management application whenever the value of sysUpTime is reset
to zero.
Note also that some agents support multiple "naming scopes", e.g.,
for an SNMPv1 agent, multiple values of the SNMPv1 community string.
For such an agent (e.g., a CNM agent which supports a different
subset of interfaces for different customers), there is no required
relationship between the ifIndex values which identify interfaces in
one naming scope and those which identify interfaces in another
naming scope. It is the agent's choice as to whether the same or
different ifIndex values identify the same or different interfaces in
different naming scopes.
Because of the restriction of the value of ifIndex to be less than
ifNumber, interfaces have been numbered with small integer values.
This has led to the ability by humans to use the ifIndex values as
(somewhat) user-friendly names for network interfaces (e.g.,
"interface number 3"). With the relaxation of the restriction on the
value of ifIndex, there is now the possibility that ifIndex values
could be assigned as very large numbers (e.g., memory addresses).
Such numbers would be much less user-friendly. Therefore, this memo
recommends that ifIndex values still be assigned as (relatively)
small integer values starting at 1, even though the values in use at
any one time are not necessarily contiguous. (Note that this makes
remembering which values have been assigned easy for agents which
dynamically add new interfaces)
A new problem is introduced by representing each sub-layer as an
ifTable entry. Previously, there usually was a simple, direct,
mapping of interfaces to the physical ports on systems. This mapping
would be based on the ifIndex value. However, by having an ifTable
entry for each interface sub-layer, mapping from interfaces to
physical ports becomes increasingly problematic.
McCloghrie & Kastenholz Standards Track [Page 13]
RFC 2863 The Interfaces Group MIB June 2000
To address this issue, a new object, ifName, is added to the MIB.
This object contains the device's local name (e.g., the name used at
the device's local console) for the interface of which the relevant
entry in the ifTable is a component. For example, consider a router
having an interface composed of PPP running over an RS-232 port. If
the router uses the name "wan1" for the (combined) interface, then
the ifName objects for the corresponding PPP and RS-232 entries in
the ifTable would both have the value "wan1". On the other hand, if
the router uses the name "wan1.1" for the PPP interface and "wan1.2"
for the RS-232 port, then the ifName objects for the corresponding
PPP and RS-232 entries in the ifTable would have the values "wan1.1"
and "wan1.2", respectively. As an another example, consider an agent
which responds to SNMP queries concerning an interface on some other
(proxied) device: if such a proxied device associates a particular
identifier with an interface, then it is appropriate to use this
identifier as the value of the interface's ifName, since the local
console in this case is that of the proxied device.
In contrast, the existing ifDescr object is intended to contain a
description of an interface, whereas another new object, ifAlias,
provides a location in which a network management application can
store a non-volatile interface-naming value of its own choice. The
ifAlias object allows a network manager to give one or more
interfaces their own unique names, irrespective of any interface-
stack relationship. Further, the ifAlias name is non-volatile, and
thus an interface must retain its assigned ifAlias value across
reboots, even if an agent chooses a new ifIndex value for the
interface.
3.1.6. Counter Size
As the speed of network media increase, the minimum time in which a
32 bit counter will wrap decreases. For example, a 10Mbs stream of
back-to-back, full-size packets causes ifInOctets to wrap in just
over 57 minutes; at 100Mbs, the minimum wrap time is 5.7 minutes, and
at 1Gbs, the minimum is 34 seconds. Requiring that interfaces be
polled frequently enough not to miss a counter wrap is increasingly
problematic.
A rejected solution to this problem was to scale the counters; for
example, ifInOctets could be changed to count received octets in,
say, 1024 byte blocks. While it would provide acceptable
functionality at high rates of the counted-events, at low rates it
suffers. If there is little traffic on an interface, there might be
a significant interval before enough of the counted-events occur to
cause the scaled counter to be incremented. Traffic would then
appear to be very bursty, leading to incorrect conclusions of the
network's performance.
McCloghrie & Kastenholz Standards Track [Page 14]
RFC 2863 The Interfaces Group MIB June 2000
Instead, this memo adopts expanded, 64 bit, counters. These counters
are provided in new "high capacity" groups. The old, 32-bit,
counters have not been deprecated. The 64-bit counters are to be
used only when the 32-bit counters do not provide enough capacity;
that is, when the 32 bit counters could wrap too fast.
For interfaces that operate at 20,000,000 (20 million) bits per
second or less, 32-bit byte and packet counters MUST be supported.
For interfaces that operate faster than 20,000,000 bits/second, and
slower than 650,000,000 bits/second, 32-bit packet counters MUST be
supported and 64-bit octet counters MUST be supported. For
interfaces that operate at 650,000,000 bits/second or faster, 64-bit
packet counters AND 64-bit octet counters MUST be supported.
These speed thresholds were chosen as reasonable compromises based on
the following:
(1) The cost of maintaining 64-bit counters is relatively high, so
minimizing the number of agents which must support them is
desirable. Common interfaces (such as 10Mbs Ethernet) should
not require them.
(2) 64-bit counters are a new feature, introduced in the SMIv2. It
is reasonable to expect that support for them will be spotty
for the immediate future. Thus, we wish to limit them to as
few systems as possible. This, in effect, means that 64-bit
counters should be limited to higher speed interfaces.
Ethernet (10,000,000 bps) and Token Ring (16,000,000 bps) are
fairly wide-spread so it seems reasonable to not require 64-bit
counters for these interfaces.
(3) The 32-bit octet counters will wrap in the following times, for
the following interfaces (when transmitting maximum-sized
packets back-to-back):
- 10Mbs Ethernet: 57 minutes,
- 16Mbs Token Ring: 36 minutes,
- a US T3 line (45 megabits): 12 minutes,
- FDDI: 5.7 minutes
(4) The 32-bit packet counters wrap in about 57 minutes when 64-
byte packets are transmitted back-to-back on a 650,000,000
bit/second link.
McCloghrie & Kastenholz Standards Track [Page 15]
RFC 2863 The Interfaces Group MIB June 2000
As an aside, a 1-terabit/second (1,000 Gbs) link will cause a 64 bit
octet counter to wrap in just under 5 years. Conversely, an
81,000,000 terabit/second link is required to cause a 64-bit counter
to wrap in 30 minutes. We believe that, while technology rapidly
marches forward, this link speed will not be achieved for at least
several years, leaving sufficient time to evaluate the introduction
of 96 bit counters.
When 64-bit counters are in use, the 32-bit counters MUST still be
available. They will report the low 32-bits of the associated 64-bit
count (e.g., ifInOctets will report the least significant 32 bits of
ifHCInOctets). This enhances inter-operability with existing
implementations at a very minimal cost to agents.
The new "high capacity" groups are:
(1) the ifHCFixedLengthGroup for character-oriented/fixed-length
interfaces, and the ifHCPacketGroup for packet-based
interfaces; both of these groups include 64 bit counters for
octets, and
(2) the ifVHCPacketGroup for packet-based interfaces; this group
includes 64 bit counters for octets and packets.
3.1.7. Interface Speed
Network speeds are increasing. The range of ifSpeed is limited to
reporting a maximum speed of (2**31)-1 bits/second, or approximately
2.2Gbs. SONET defines an OC-48 interface, which is defined at
operating at 48 times 51 Mbs, which is a speed in excess of 2.4Gbs.
Thus, ifSpeed is insufficient for the future, and this memo defines
an additional object: ifHighSpeed.
The ifHighSpeed object reports the speed of the interface in
1,000,000 (1 million) bits/second units. Thus, the true speed of the
interface will be the value reported by this object, plus or minus
500,000 bits/second.
Other alternatives considered (but rejected) were:
(1) Making the interface speed a 64-bit gauge. This was rejected
since the current SMI does not allow such a syntax.
Furthermore, even if 64-bit gauges were available, their use would
require additional complexity in agents due to an increased
requirement for 64-bit operations.
McCloghrie & Kastenholz Standards Track [Page 16]
RFC 2863 The Interfaces Group MIB June 2000
(2) We also considered making "high-32 bit" and "low-32-bit"
objects which, when combined, would be a 64-bit value. This
simply seemed overly complex for what we are trying to do.
Furthermore, a full 64-bits of precision does not seem necessary.
The value of ifHighSpeed will be the only report of interface
speed for interfaces that are faster than 4,294,967,295 bits per
second. At this speed, the granularity of ifHighSpeed will be
1,000,000 bits per second, thus the error will be 1/4294, or about
0.02%. This seems reasonable.
(3) Adding a "scale" object, which would define the units which
ifSpeed's value is.
This would require two additional objects; one for the scaling
object, and one to replace the current ifSpeed. This later object
is required since the semantics of ifSpeed would be significantly
altered, and manager stations which do not understand the new
semantics would be confused.
3.1.8. Multicast/Broadcast Counters
In MIB-II, the ifTable counters for multicast and broadcast packets
are combined as counters of non-unicast packets. In contrast, the
ifExtensions MIB [19] defined one set of counters for multicast, and
a separate set for broadcast packets. With the separate counters,
the original combined counters become redundant. To avoid this
redundancy, the non-unicast counters are deprecated.
For the output broadcast and multicast counters defined in RFC 1229,
their definitions varied slightly from the packet counters in the
ifTable, in that they did not count errors/discarded packets. Thus,
this memo defines new objects with better aligned definitions.
Counters with 64 bits of range are also needed, as explained above.
3.1.9. Trap Enable
In the multi-layer interface model, each sub-layer for which there is
an entry in the ifTable can generate linkUp/linkDown Traps. Since
interface state changes would tend to propagate through the interface
(from top to bottom, or bottom to top), it is likely that several
traps would be generated for each linkUp/linkDown occurrence.
It is desirable to provide a mechanism for manager stations to
control the generation of these traps. To this end, the
ifLinkUpDownTrapEnable object has been added. This object allows
managers to limit generation of traps to just the sub-layers of
interest.
McCloghrie & Kastenholz Standards Track [Page 17]
RFC 2863 The Interfaces Group MIB June 2000
The default setting should limit the number of traps generated to one
per interface per linkUp/linkDown event. Furthermore, it seems that
the state changes of most interest to network managers occur at the
lowest level of an interface stack. Therefore we specify that by
default, only the lowest sub-layer of the interface generate traps.
3.1.10. Addition of New ifType values
Over time, there is the need to add new ifType enumerated values for
new interface types. If the syntax of ifType were defined in the MIB
in section 6, then a new version of this MIB would have to be re-
issued in order to define new values. In the past, re-issuing of a
MIB has occurred only after several years.
Therefore, the syntax of ifType is changed to be a textual
convention, such that the enumerated integer values are now defined
in the textual convention, IANAifType, defined in a different
document. This allows additional values to be documented without
having to re-issue a new version of this document. The Internet
Assigned Number Authority (IANA) is responsible for the assignment of
all Internet numbers, including various SNMP-related numbers, and
specifically, new ifType values.
3.1.11. InterfaceIndex Textual Convention
A new textual convention, InterfaceIndex, has been defined. This
textual convention "contains" all of the semantics of the ifIndex
object. This allows other MIB modules to easily import the semantics
of ifIndex.
3.1.12. New states for IfOperStatus
Three new states have been added to ifOperStatus: 'dormant',
'notPresent', and 'lowerLayerDown'.
The dormant state indicates that the relevant interface is not
actually in a condition to pass packets (i.e., it is not 'up') but is
in a "pending" state, waiting for some external event. For "on-
demand" interfaces, this new state identifies the situation where the
interface is waiting for events to place it in the up state.
Examples of such events might be:
(1) having packets to transmit before establishing a connection to
a remote system;
(2) having a remote system establish a connection to the interface
(e.g. dialing up to a slip-server).
McCloghrie & Kastenholz Standards Track [Page 18]
RFC 2863 The Interfaces Group MIB June 2000
The notPresent state is a refinement on the down state which
indicates that the relevant interface is down specifically because
some component (typically, a hardware component) is not present in
the managed system. Examples of use of the notPresent state are:
(1) to allow an interface's conceptual row including its counter
values to be retained across a "hot swap" of a card/module,
and/or
(2) to allow an interface's conceptual row to be created, and
thereby enable interfaces to be pre-configured prior to
installation of the hardware needed to make the interface
operational.
Agents are not required to support interfaces in the notPresent
state. However, from a conceptual viewpoint, when a row in the
ifTable is created, it first enters the notPresent state and then
subsequently transitions into the down state; similarly, when a row
in the ifTable is deleted, it first enters the notPresent state and
then subsequently the object instances are deleted. For an agent
with no support for notPresent, both of these transitions (from the
notPresent state to the down state, and from the notPresent state to
the instances being removed) are immediate, i.e., the transition does
not last long enough to be recorded by ifOperStatus. Even for those
agents which do support interfaces in the notPresent state, the
length of time and conditions under which an interface stays in the
notPresent state is implementation-specific.
The lowerLayerDown state is also a refinement on the down state.
This new state indicates that this interface runs "on top of" one or
more other interfaces (see ifStackTable) and that this interface is
down specifically because one or more of these lower-layer interfaces
are down.
3.1.13. IfAdminStatus and IfOperStatus
The down state of ifOperStatus now has two meanings, depending on the
value of ifAdminStatus.
(1) if ifAdminStatus is not down and ifOperStatus is down then a
fault condition is presumed to exist on the interface.
(2) if ifAdminStatus is down, then ifOperStatus will normally also
be down (or notPresent) i.e., there is not (necessarily) a
fault condition on the interface.
Note that when ifAdminStatus transitions to down, ifOperStatus will
normally also transition to down. In this situation, it is possible
McCloghrie & Kastenholz Standards Track [Page 19]
RFC 2863 The Interfaces Group MIB June 2000
that ifOperStatus's transition will not occur immediately, but rather
after a small time lag to complete certain operations before going
"down"; for example, it might need to finish transmitting a packet.
If a manager station finds that ifAdminStatus is down and
ifOperStatus is not down for a particular interface, the manager
station should wait a short while and check again. If the condition
still exists, only then should it raise an error indication.
Naturally, it should also ensure that ifLastChange has not changed
during this interval.
Whenever an interface table entry is created (usually as a result of
system initialization), the relevant instance of ifAdminStatus is set
to down, and ifOperStatus will be down or notPresent.
An interface may be enabled in two ways: either as a result of
explicit management action (e.g. setting ifAdminStatus to up) or as a
result of the managed system's initialization process. When
ifAdminStatus changes to the up state, the related ifOperStatus
should do one of the following:
(1) Change to the up state if and only if the interface is able to
send and receive packets.
(2) Change to the lowerLayerDown state if and only if the interface
is prevented from entering the up state because of the state of
one or more of the interfaces beneath it in the interface
stack.
(3) Change to the dormant state if and only if the interface is
found to be operable, but the interface is waiting for other,
external, events to occur before it can transmit or receive
packets. Presumably when the expected events occur, the
interface will then change to the up state.
(4) Remain in the down state if an error or other fault condition
is detected on the interface.
(5) Change to the unknown state if, for some reason, the state of
the interface can not be ascertained.
(6) Change to the testing state if some test(s) must be performed
on the interface. Presumably after completion of the test, the
interface's state will change to up, dormant, or down, as
appropriate.
(7) Remain in the notPresent state if interface components are
missing.
McCloghrie & Kastenholz Standards Track [Page 20]
RFC 2863 The Interfaces Group MIB June 2000
3.1.14. IfOperStatus in an Interface Stack
When an interface is a part of an interface-stack, but is not the
lowest interface in the stack, then:
(1) ifOperStatus has the value 'up' if it is able to pass packets
due to one or more interfaces below it in the stack being 'up',
irrespective of whether other interfaces below it are 'down', '
dormant', 'notPresent', 'lowerLayerDown', 'unknown' or '
testing'.
(2) ifOperStatus may have the value 'up' or 'dormant' if one or
more interfaces below it in the stack are 'dormant', and all
others below it are either 'down', 'dormant', 'notPresent', '
lowerLayerDown', 'unknown' or 'testing'.
(3) ifOperStatus has the value 'lowerLayerDown' while all
interfaces below it in the stack are either 'down', '
notPresent', 'lowerLayerDown', or 'testing'.
3.1.15. Traps
The exact definition of when linkUp and linkDown traps are generated
has been changed to reflect the changes to ifAdminStatus and
ifOperStatus. Operational experience indicates that management
stations are most concerned with an interface being in the down state
and the fact that this state may indicate a failure. Thus, it is
most useful to instrument transitions into/out of either the up state
or the down state.
Instrumenting transitions into or out of the up state was rejected
since it would have the drawback that a demand interface might have
many transitions between up and dormant, leading to many linkUp traps
and no linkDown traps. Furthermore, if a node's only interface is
the demand interface, then a transition to dormant would entail
generation of a linkDown trap, necessitating bringing the link to the
up state (and a linkUp trap)!!
On the other hand, instrumenting transitions into or out of the down
state (to/from all other states except notPresent) has the
advantages:
(1) A transition into the down state (from a state other than
notPresent) will occur when an error is detected on an
interface. Error conditions are presumably of great interest
to network managers.
McCloghrie & Kastenholz Standards Track [Page 21]
RFC 2863 The Interfaces Group MIB June 2000
(2) Departing the down state (to a state other than the notPresent
state) generally indicates that the interface is going to
either up or dormant, both of which are considered "healthy"
states.
Furthermore, it is believed that generating traps on transitions into
or out of the down state (except to/from the notPresent state) is
generally consistent with current usage and interpretation of these
traps by manager stations.
Transitions to/from the notPresent state are concerned with the
insertion and removal of hardware, and are outside the scope of these
traps.
Therefore, this memo defines that LinkUp and linkDown traps are
generated just after ifOperStatus leaves, or just before it enters,
the down state, respectively; except that LinkUp and linkDown traps
are never generated on transitions to/from the notPresent state. For
the purpose of deciding when these traps occur, the lowerLayerDown
state and the down state are considered to be equivalent, i.e., there
is no trap on transition from lowerLayerDown into down, and there is
a trap on transition from any other state except down (and
notPresent) into lowerLayerDown.
Note that this definition allows a node with only one interface to
transmit a linkDown trap before that interface goes down. (Of
course, when the interface is going down because of a failure
condition, the linkDown trap probably cannot be successfully
transmitted anyway.)
Some interfaces perform a link "training" function when trying to
bring the interface up. In the event that such an interface were
defective, then the training function would fail and the interface
would remain down, and the training function might be repeated at
appropriate intervals. If the interface, while performing this
training function, were considered to the in the testing state, then
linkUp and linkDown traps would be generated for each start and end
of the training function. This is not the intent of the linkUp and
linkDown traps, and therefore, while performing such a training
function, the interface's state should be represented as down.
An exception to the above generation of linkUp/linkDown traps on
changes in ifOperStatus, occurs when an interface is "flapping",
i.e., when it is rapidly oscillating between the up and down states.
If traps were generated for each such oscillation, the network and
the network management system would be flooded with unnecessary
traps. In such a situation, the agent should limit the rate at which
it generates traps.
McCloghrie & Kastenholz Standards Track [Page 22]
RFC 2863 The Interfaces Group MIB June 2000
3.1.16. ifSpecific
The original definition of the OBJECT IDENTIFIER value of ifSpecific
was not sufficiently clear. As a result, different implementors used
it differently, and confusion resulted. Some implementations set the
value of ifSpecific to the OBJECT IDENTIFIER that defines the media-
specific MIB, i.e., the "foo" of:
foo OBJECT IDENTIFIER ::= { transmission xxx }
while others set it to be OBJECT IDENTIFIER of the specific table or
entry in the appropriate media-specific MIB (i.e., fooTable or
fooEntry), while still others set it be the OBJECT IDENTIFIER of the
index object of the table's row, including instance identifier,
(i.e., fooIfIndex.ifIndex). A definition based on the latter would
not be sufficient unless it also allowed for media-specific MIBs
which include several tables, where each table has its own
(different) indexing.
The only definition that can both be made explicit and can cover all
the useful situations is to have ifSpecific be the most general value
for the media-specific MIB module (the first example given above).
This effectively makes it redundant because it contains no more
information than is provided by ifType. Thus, ifSpecific has been
deprecated.
3.1.17. Creation/Deletion of Interfaces
While some interfaces, for example, most physical interfaces, cannot
be created via network management, other interfaces such as logical
interfaces sometimes can be. The ifTable contains only generic
information about an interface. Almost all 'create-able' interfaces
have other, media-specific, information through which configuration
parameters may be supplied prior to creating such an interface.
Thus, the ifTable does not itself support the creation or deletion of
an interface (specifically, it has no RowStatus [6] column). Rather,
if a particular interface type supports the dynamic creation and/or
deletion of an interface of that type, then that media-specific MIB
should include an appropriate RowStatus object (see the ATM LAN-
Emulation Client MIB [20] for an example of a MIB which does this).
Typically, when such a RowStatus object is created/deleted, then the
conceptual row in the ifTable appears/disappears as a by-product, and
an ifIndex value (chosen by the agent) is stored in an appropriate
object in the media-specific MIB.
McCloghrie & Kastenholz Standards Track [Page 23]
RFC 2863 The Interfaces Group MIB June 2000
3.1.18. All Values Must be Known
There are a number of situations where an agent does not know the
value of one or more objects for a particular interface. In all such
circumstances, an agent MUST NOT instantiate an object with an
incorrect value; rather, it MUST respond with the appropriate
error/exception condition (e.g., noSuchInstance or noSuchName).
One example is where an agent is unable to count the occurrences
defined by one (or more) of the ifTable counters. In this
circumstance, the agent MUST NOT instantiate the particular counter
with a value of, say, zero. To do so would be to provide mis-
information to a network management application reading the zero
value, and thereby assuming that there have been no occurrences of
the event (e.g., no input errors because ifInErrors is always zero).
Sometimes the lack of knowledge of an object's value is temporary.
For example, when the MTU of an interface is a configured value and a
device dynamically learns the configured value through (after)
exchanging messages over the interface (e.g., ATM LAN-Emulation
[20]). In such a case, the value is not known until after the
ifTable entry has already been created. In such a case, the ifTable
entry should be created without an instance of the object whose value
is unknown; later, when the value becomes known, the missing object
can then be instantiated (e.g., the instance of ifMtu is only
instantiated once the interface's MTU becomes known).
As a result of this "known values" rule, management applications MUST
be able to cope with the responses to retrieving the object instances
within a conceptual row of the ifTable revealing that some of the
row's columnar objects are missing/not available.
4. Media-Specific MIB Applicability
The exact use and semantics of many objects in this MIB are open to
some interpretation. This is a result of the generic nature of this
MIB. It is not always possible to come up with specific,
unambiguous, text that covers all cases and yet preserves the generic
nature of the MIB.
Therefore, it is incumbent upon a media-specific MIB designer to,
wherever necessary, clarify the use of the objects in this MIB with
respect to the media-specific MIB.
McCloghrie & Kastenholz Standards Track [Page 24]
RFC 2863 The Interfaces Group MIB June 2000
Specific areas of clarification include
Layering Model
The media-specific MIB designer MUST completely and unambiguously
specify the layering model used. Each individual sub-layer must
be identified, as must the ifStackTable's portrayal of the
relationship(s) between the sub-layers.
Virtual Circuits
The media-specific MIB designer MUST specify whether virtual
circuits are assigned entries in the ifTable or not. If they are,
compelling rationale must be presented.
ifRcvAddressTable
The media-specific MIB designer MUST specify the applicability of
the ifRcvAddressTable.
ifType
For each of the ifType values to which the media-specific MIB
applies, it must specify the mapping of ifType values to media-
specific MIB module(s) and instances of MIB objects within those
modules.
ifXxxOctets
The definitions of ifInOctets and ifOutOctets (and similarly,
ifHCInOctets and ifHCOutOctets) specify that their values include
framing characters. The media-specific MIB designer MUST specify
any special conditions of the media concerning the inclusion of
framing characters, especially with respect to frames with errors.
However, wherever this interface MIB is specific in the semantics,
DESCRIPTION, or applicability of objects, the media-specific MIB
designer MUST NOT change said semantics, DESCRIPTION, or
applicability.
5. Overview
This MIB consists of 4 tables:
ifTable
This table is the ifTable from MIB-II.
ifXTable
This table contains objects that have been added to the Interface
MIB as a result of the Interface Evolution effort, or replacements
for objects of the original (MIB-II) ifTable that were deprecated
McCloghrie & Kastenholz Standards Track [Page 25]
RFC 2863 The Interfaces Group MIB June 2000
because the semantics of said objects have significantly changed.
This table also contains objects that were previously in the
ifExtnsTable.
ifStackTable
This table contains objects that define the relationships among
the sub-layers of an interface.
ifRcvAddressTable
This table contains objects that are used to define the media-
level addresses which this interface will receive. This table is
a generic table. The designers of media-specific MIBs must define
exactly how this table applies to their specific MIB.
6. Interfaces Group Definitions
IF-MIB DEFINITIONS ::= BEGIN
IMPORTS
MODULE-IDENTITY, OBJECT-TYPE, Counter32, Gauge32, Counter64,
Integer32, TimeTicks, mib-2,
NOTIFICATION-TYPE FROM SNMPv2-SMI
TEXTUAL-CONVENTION, DisplayString,
PhysAddress, TruthValue, RowStatus,
TimeStamp, AutonomousType, TestAndIncr FROM SNMPv2-TC
MODULE-COMPLIANCE, OBJECT-GROUP,
NOTIFICATION-GROUP FROM SNMPv2-CONF
snmpTraps FROM SNMPv2-MIB
IANAifType FROM IANAifType-MIB;
ifMIB MODULE-IDENTITY
LAST-UPDATED "200006140000Z"
ORGANIZATION "IETF Interfaces MIB Working Group"
CONTACT-INFO
" Keith McCloghrie
Cisco Systems, Inc.
170 West Tasman Drive
San Jose, CA 95134-1706
US
408-526-5260
kzm@cisco.com"
DESCRIPTION
"The MIB module to describe generic objects for network
interface sub-layers. This MIB is an updated version of
MIB-II's ifTable, and incorporates the extensions defined in
RFC 1229."
McCloghrie & Kastenholz Standards Track [Page 26]
RFC 2863 The Interfaces Group MIB June 2000
REVISION "200006140000Z"
DESCRIPTION
"Clarifications agreed upon by the Interfaces MIB WG, and
published as RFC 2863."
REVISION "199602282155Z"
DESCRIPTION
"Revisions made by the Interfaces MIB WG, and published in
RFC 2233."
REVISION "199311082155Z"
DESCRIPTION
"Initial revision, published as part of RFC 1573."
::= { mib-2 31 }
ifMIBObjects OBJECT IDENTIFIER ::= { ifMIB 1 }
interfaces OBJECT IDENTIFIER ::= { mib-2 2 }
--
-- Textual Conventions
--
-- OwnerString has the same semantics as used in RFC 1271
OwnerString ::= TEXTUAL-CONVENTION
DISPLAY-HINT "255a"
STATUS deprecated
DESCRIPTION
"This data type is used to model an administratively
assigned name of the owner of a resource. This information
is taken from the NVT ASCII character set. It is suggested
that this name contain one or more of the following: ASCII
form of the manager station's transport address, management
station name (e.g., domain name), network management
personnel's name, location, or phone number. In some cases
the agent itself will be the owner of an entry. In these
cases, this string shall be set to a string starting with
'agent'."
SYNTAX OCTET STRING (SIZE(0..255))
-- InterfaceIndex contains the semantics of ifIndex and should be used
-- for any objects defined in other MIB modules that need these semantics.
InterfaceIndex ::= TEXTUAL-CONVENTION
DISPLAY-HINT "d"
STATUS current
DESCRIPTION
McCloghrie & Kastenholz Standards Track [Page 27]
RFC 2863 The Interfaces Group MIB June 2000
"A unique value, greater than zero, for each interface or
interface sub-layer in the managed system. It is
recommended that values are assigned contiguously starting
from 1. The value for each interface sub-layer must remain
constant at least from one re-initialization of the entity's
network management system to the next re-initialization."
SYNTAX Integer32 (1..2147483647)
InterfaceIndexOrZero ::= TEXTUAL-CONVENTION
DISPLAY-HINT "d"
STATUS current
DESCRIPTION
"This textual convention is an extension of the
InterfaceIndex convention. The latter defines a greater
than zero value used to identify an interface or interface
sub-layer in the managed system. This extension permits the
additional value of zero. the value zero is object-specific
and must therefore be defined as part of the description of
any object which uses this syntax. Examples of the usage of
zero might include situations where interface was unknown,
or when none or all interfaces need to be referenced."
SYNTAX Integer32 (0..2147483647)
ifNumber OBJECT-TYPE
SYNTAX Integer32
MAX-ACCESS read-only
STATUS current
DESCRIPTION
"The number of network interfaces (regardless of their
current state) present on this system."
::= { interfaces 1 }
ifTableLastChange OBJECT-TYPE
SYNTAX TimeTicks
MAX-ACCESS read-only
STATUS current
DESCRIPTION
"The value of sysUpTime at the time of the last creation or
deletion of an entry in the ifTable. If the number of
entries has been unchanged since the last re-initialization
of the local network management subsystem, then this object
contains a zero value."
::= { ifMIBObjects 5 }
-- the Interfaces table
-- The Interfaces table contains information on the entity's
McCloghrie & Kastenholz Standards Track [Page 28]
RFC 2863 The Interfaces Group MIB June 2000
-- interfaces. Each sub-layer below the internetwork-layer
-- of a network interface is considered to be an interface.
ifTable OBJECT-TYPE
SYNTAX SEQUENCE OF IfEntry
MAX-ACCESS not-accessible
STATUS current
DESCRIPTION
"A list of interface entries. The number of entries is
given by the value of ifNumber."
::= { interfaces 2 }
ifEntry OBJECT-TYPE
SYNTAX IfEntry
MAX-ACCESS not-accessible
STATUS current
DESCRIPTION
"An entry containing management information applicable to a
particular interface."
INDEX { ifIndex }
::= { ifTable 1 }
IfEntry ::=
SEQUENCE {
ifIndex InterfaceIndex,
ifDescr DisplayString,
ifType IANAifType,
ifMtu Integer32,
ifSpeed Gauge32,
ifPhysAddress PhysAddress,
ifAdminStatus INTEGER,
ifOperStatus INTEGER,
ifLastChange TimeTicks,
ifInOctets Counter32,
ifInUcastPkts Counter32,
ifInNUcastPkts Counter32, -- deprecated
ifInDiscards Counter32,
ifInErrors Counter32,
ifInUnknownProtos Counter32,
ifOutOctets Counter32,
ifOutUcastPkts Counter32,
ifOutNUcastPkts Counter32, -- deprecated
ifOutDiscards Counter32,
ifOutErrors Counter32,
ifOutQLen Gauge32, -- deprecated
ifSpecific OBJECT IDENTIFIER -- deprecated
}
McCloghrie & Kastenholz Standards Track [Page 29]
RFC 2863 The Interfaces Group MIB June 2000
ifIndex OBJECT-TYPE
SYNTAX InterfaceIndex
MAX-ACCESS read-only
STATUS current
DESCRIPTION
"A unique value, greater than zero, for each interface. It
is recommended that values are assigned contiguously
starting from 1. The value for each interface sub-layer
must remain constant at least from one re-initialization of
the entity's network management system to the next re-
initialization."
::= { ifEntry 1 }
ifDescr OBJECT-TYPE
SYNTAX DisplayString (SIZE (0..255))
MAX-ACCESS read-only
STATUS current
DESCRIPTION
"A textual string containing information about the
interface. This string should include the name of the
manufacturer, the product name and the version of the
interface hardware/software."
::= { ifEntry 2 }
ifType OBJECT-TYPE
SYNTAX IANAifType
MAX-ACCESS read-only
STATUS current
DESCRIPTION
"The type of interface. Additional values for ifType are
assigned by the Internet Assigned Numbers Authority (IANA),
through updating the syntax of the IANAifType textual
convention."
::= { ifEntry 3 }
ifMtu OBJECT-TYPE
SYNTAX Integer32
MAX-ACCESS read-only
STATUS current
DESCRIPTION
"The size of the largest packet which can be sent/received
on the interface, specified in octets. For interfaces that
are used for transmitting network datagrams, this is the
size of the largest network datagram that can be sent on the
interface."
::= { ifEntry 4 }
ifSpeed OBJECT-TYPE
McCloghrie & Kastenholz Standards Track [Page 30]
RFC 2863 The Interfaces Group MIB June 2000
SYNTAX Gauge32
MAX-ACCESS read-only
STATUS current
DESCRIPTION
"An estimate of the interface's current bandwidth in bits
per second. For interfaces which do not vary in bandwidth
or for those where no accurate estimation can be made, this
object should contain the nominal bandwidth. If the
bandwidth of the interface is greater than the maximum value
reportable by this object then this object should report its
maximum value (4,294,967,295) and ifHighSpeed must be used
to report the interace's speed. For a sub-layer which has
no concept of bandwidth, this object should be zero."
::= { ifEntry 5 }
ifPhysAddress OBJECT-TYPE
SYNTAX PhysAddress
MAX-ACCESS read-only
STATUS current
DESCRIPTION
"The interface's address at its protocol sub-layer. For
example, for an 802.x interface, this object normally
contains a MAC address. The interface's media-specific MIB
must define the bit and byte ordering and the format of the
value of this object. For interfaces which do not have such
an address (e.g., a serial line), this object should contain
an octet string of zero length."
::= { ifEntry 6 }
ifAdminStatus OBJECT-TYPE
SYNTAX INTEGER {
up(1), -- ready to pass packets
down(2),
testing(3) -- in some test mode
}
MAX-ACCESS read-write
STATUS current
DESCRIPTION
"The desired state of the interface. The testing(3) state
indicates that no operational packets can be passed. When a
managed system initializes, all interfaces start with
ifAdminStatus in the down(2) state. As a result of either
explicit management action or per configuration information
retained by the managed system, ifAdminStatus is then
changed to either the up(1) or testing(3) states (or remains
in the down(2) state)."
::= { ifEntry 7 }
McCloghrie & Kastenholz Standards Track [Page 31]
RFC 2863 The Interfaces Group MIB June 2000
ifOperStatus OBJECT-TYPE
SYNTAX INTEGER {
up(1), -- ready to pass packets
down(2),
testing(3), -- in some test mode
unknown(4), -- status can not be determined
-- for some reason.
dormant(5),
notPresent(6), -- some component is missing
lowerLayerDown(7) -- down due to state of
-- lower-layer interface(s)
}
MAX-ACCESS read-only
STATUS current
DESCRIPTION
"The current operational state of the interface. The
testing(3) state indicates that no operational packets can
be passed. If ifAdminStatus is down(2) then ifOperStatus
should be down(2). If ifAdminStatus is changed to up(1)
then ifOperStatus should change to up(1) if the interface is
ready to transmit and receive network traffic; it should
change to dormant(5) if the interface is waiting for
external actions (such as a serial line waiting for an
incoming connection); it should remain in the down(2) state
if and only if there is a fault that prevents it from going
to the up(1) state; it should remain in the notPresent(6)
state if the interface has missing (typically, hardware)
components."
::= { ifEntry 8 }
ifLastChange OBJECT-TYPE
SYNTAX TimeTicks
MAX-ACCESS read-only
STATUS current
DESCRIPTION
"The value of sysUpTime at the time the interface entered
its current operational state. If the current state was
entered prior to the last re-initialization of the local
network management subsystem, then this object contains a
zero value."
::= { ifEntry 9 }
ifInOctets OBJECT-TYPE
SYNTAX Counter32
MAX-ACCESS read-only
STATUS current
DESCRIPTION
"The total number of octets received on the interface,
McCloghrie & Kastenholz Standards Track [Page 32]
RFC 2863 The Interfaces Group MIB June 2000
including framing characters.
Discontinuities in the value of this counter can occur at
re-initialization of the management system, and at other
times as indicated by the value of
ifCounterDiscontinuityTime."
::= { ifEntry 10 }
ifInUcastPkts OBJECT-TYPE
SYNTAX Counter32
MAX-ACCESS read-only
STATUS current
DESCRIPTION
"The number of packets, delivered by this sub-layer to a
higher (sub-)layer, which were not addressed to a multicast
or broadcast address at this sub-layer.
Discontinuities in the value of this counter can occur at
re-initialization of the management system, and at other
times as indicated by the value of
ifCounterDiscontinuityTime."
::= { ifEntry 11 }
ifInNUcastPkts OBJECT-TYPE
SYNTAX Counter32
MAX-ACCESS read-only
STATUS deprecated
DESCRIPTION
"The number of packets, delivered by this sub-layer to a
higher (sub-)layer, which were addressed to a multicast or
broadcast address at this sub-layer.
Discontinuities in the value of this counter can occur at
re-initialization of the management system, and at other
times as indicated by the value of
ifCounterDiscontinuityTime.
This object is deprecated in favour of ifInMulticastPkts and
ifInBroadcastPkts."
::= { ifEntry 12 }
ifInDiscards OBJECT-TYPE
SYNTAX Counter32
MAX-ACCESS read-only
STATUS current
DESCRIPTION
"The number of inbound packets which were chosen to be
discarded even though no errors had been detected to prevent
McCloghrie & Kastenholz Standards Track [Page 33]
RFC 2863 The Interfaces Group MIB June 2000
their being deliverable to a higher-layer protocol. One
possible reason for discarding such a packet could be to
free up buffer space.
Discontinuities in the value of this counter can occur at
re-initialization of the management system, and at other
times as indicated by the value of
ifCounterDiscontinuityTime."
::= { ifEntry 13 }
ifInErrors OBJECT-TYPE
SYNTAX Counter32
MAX-ACCESS read-only
STATUS current
DESCRIPTION
"For packet-oriented interfaces, the number of inbound
packets that contained errors preventing them from being
deliverable to a higher-layer protocol. For character-
oriented or fixed-length interfaces, the number of inbound
transmission units that contained errors preventing them
from being deliverable to a higher-layer protocol.
Discontinuities in the value of this counter can occur at
re-initialization of the management system, and at other
times as indicated by the value of
ifCounterDiscontinuityTime."
::= { ifEntry 14 }
ifInUnknownProtos OBJECT-TYPE
SYNTAX Counter32
MAX-ACCESS read-only
STATUS current
DESCRIPTION
"For packet-oriented interfaces, the number of packets
received via the interface which were discarded because of
an unknown or unsupported protocol. For character-oriented
or fixed-length interfaces that support protocol
multiplexing the number of transmission units received via
the interface which were discarded because of an unknown or
unsupported protocol. For any interface that does not
support protocol multiplexing, this counter will always be
0.
Discontinuities in the value of this counter can occur at
re-initialization of the management system, and at other
times as indicated by the value of
ifCounterDiscontinuityTime."
::= { ifEntry 15 }
McCloghrie & Kastenholz Standards Track [Page 34]
RFC 2863 The Interfaces Group MIB June 2000
ifOutOctets OBJECT-TYPE
SYNTAX Counter32
MAX-ACCESS read-only
STATUS current
DESCRIPTION
"The total number of octets transmitted out of the
interface, including framing characters.
Discontinuities in the value of this counter can occur at
re-initialization of the management system, and at other
times as indicated by the value of
ifCounterDiscontinuityTime."
::= { ifEntry 16 }
ifOutUcastPkts OBJECT-TYPE
SYNTAX Counter32
MAX-ACCESS read-only
STATUS current
DESCRIPTION
"The total number of packets that higher-level protocols
requested be transmitted, and which were not addressed to a
multicast or broadcast address at this sub-layer, including
those that were discarded or not sent.
Discontinuities in the value of this counter can occur at
re-initialization of the management system, and at other
times as indicated by the value of
ifCounterDiscontinuityTime."
::= { ifEntry 17 }
ifOutNUcastPkts OBJECT-TYPE
SYNTAX Counter32
MAX-ACCESS read-only
STATUS deprecated
DESCRIPTION
"The total number of packets that higher-level protocols
requested be transmitted, and which were addressed to a
multicast or broadcast address at this sub-layer, including
those that were discarded or not sent.
Discontinuities in the value of this counter can occur at
re-initialization of the management system, and at other
times as indicated by the value of
ifCounterDiscontinuityTime.
This object is deprecated in favour of ifOutMulticastPkts
and ifOutBroadcastPkts."
::= { ifEntry 18 }
McCloghrie & Kastenholz Standards Track [Page 35]
RFC 2863 The Interfaces Group MIB June 2000
ifOutDiscards OBJECT-TYPE
SYNTAX Counter32
MAX-ACCESS read-only
STATUS current
DESCRIPTION
"The number of outbound packets which were chosen to be
discarded even though no errors had been detected to prevent
their being transmitted. One possible reason for discarding
such a packet could be to free up buffer space.
Discontinuities in the value of this counter can occur at
re-initialization of the management system, and at other
times as indicated by the value of
ifCounterDiscontinuityTime."
::= { ifEntry 19 }
ifOutErrors OBJECT-TYPE
SYNTAX Counter32
MAX-ACCESS read-only
STATUS current
DESCRIPTION
"For packet-oriented interfaces, the number of outbound
packets that could not be transmitted because of errors.
For character-oriented or fixed-length interfaces, the
number of outbound transmission units that could not be
transmitted because of errors.
Discontinuities in the value of this counter can occur at
re-initialization of the management system, and at other
times as indicated by the value of
ifCounterDiscontinuityTime."
::= { ifEntry 20 }
ifOutQLen OBJECT-TYPE
SYNTAX Gauge32
MAX-ACCESS read-only
STATUS deprecated
DESCRIPTION
"The length of the output packet queue (in packets)."
::= { ifEntry 21 }
ifSpecific OBJECT-TYPE
SYNTAX OBJECT IDENTIFIER
MAX-ACCESS read-only
STATUS deprecated
DESCRIPTION
"A reference to MIB definitions specific to the particular
media being used to realize the interface. It is
McCloghrie & Kastenholz Standards Track [Page 36]
RFC 2863 The Interfaces Group MIB June 2000
recommended that this value point to an instance of a MIB
object in the media-specific MIB, i.e., that this object
have the semantics associated with the InstancePointer
textual convention defined in RFC 2579. In fact, it is
recommended that the media-specific MIB specify what value
ifSpecific should/can take for values of ifType. If no MIB
definitions specific to the particular media are available,
the value should be set to the OBJECT IDENTIFIER { 0 0 }."
::= { ifEntry 22 }
--
-- Extension to the interface table
--
-- This table replaces the ifExtnsTable table.
--
ifXTable OBJECT-TYPE
SYNTAX SEQUENCE OF IfXEntry
MAX-ACCESS not-accessible
STATUS current
DESCRIPTION
"A list of interface entries. The number of entries is
given by the value of ifNumber. This table contains
additional objects for the interface table."
::= { ifMIBObjects 1 }
ifXEntry OBJECT-TYPE
SYNTAX IfXEntry
MAX-ACCESS not-accessible
STATUS current
DESCRIPTION
"An entry containing additional management information
applicable to a particular interface."
AUGMENTS { ifEntry }
::= { ifXTable 1 }
IfXEntry ::=
SEQUENCE {
ifName DisplayString,
ifInMulticastPkts Counter32,
ifInBroadcastPkts Counter32,
ifOutMulticastPkts Counter32,
ifOutBroadcastPkts Counter32,
ifHCInOctets Counter64,
ifHCInUcastPkts Counter64,
ifHCInMulticastPkts Counter64,
McCloghrie & Kastenholz Standards Track [Page 37]
RFC 2863 The Interfaces Group MIB June 2000
ifHCInBroadcastPkts Counter64,
ifHCOutOctets Counter64,
ifHCOutUcastPkts Counter64,
ifHCOutMulticastPkts Counter64,
ifHCOutBroadcastPkts Counter64,
ifLinkUpDownTrapEnable INTEGER,
ifHighSpeed Gauge32,
ifPromiscuousMode TruthValue,
ifConnectorPresent TruthValue,
ifAlias DisplayString,
ifCounterDiscontinuityTime TimeStamp
}
ifName OBJECT-TYPE
SYNTAX DisplayString
MAX-ACCESS read-only
STATUS current
DESCRIPTION
"The textual name of the interface. The value of this
object should be the name of the interface as assigned by
the local device and should be suitable for use in commands
entered at the device's `console'. This might be a text
name, such as `le0' or a simple port number, such as `1',
depending on the interface naming syntax of the device. If
several entries in the ifTable together represent a single
interface as named by the device, then each will have the
same value of ifName. Note that for an agent which responds
to SNMP queries concerning an interface on some other
(proxied) device, then the value of ifName for such an
interface is the proxied device's local name for it.
If there is no local name, or this object is otherwise not
applicable, then this object contains a zero-length string."
::= { ifXEntry 1 }
ifInMulticastPkts OBJECT-TYPE
SYNTAX Counter32
MAX-ACCESS read-only
STATUS current
DESCRIPTION
"The number of packets, delivered by this sub-layer to a
higher (sub-)layer, which were addressed to a multicast
address at this sub-layer. For a MAC layer protocol, this
includes both Group and Functional addresses.
Discontinuities in the value of this counter can occur at
re-initialization of the management system, and at other
McCloghrie & Kastenholz Standards Track [Page 38]
RFC 2863 The Interfaces Group MIB June 2000
times as indicated by the value of
ifCounterDiscontinuityTime."
::= { ifXEntry 2 }
ifInBroadcastPkts OBJECT-TYPE
SYNTAX Counter32
MAX-ACCESS read-only
STATUS current
DESCRIPTION
"The number of packets, delivered by this sub-layer to a
higher (sub-)layer, which were addressed to a broadcast
address at this sub-layer.
Discontinuities in the value of this counter can occur at
re-initialization of the management system, and at other
times as indicated by the value of
ifCounterDiscontinuityTime."
::= { ifXEntry 3 }
ifOutMulticastPkts OBJECT-TYPE
SYNTAX Counter32
MAX-ACCESS read-only
STATUS current
DESCRIPTION
"The total number of packets that higher-level protocols
requested be transmitted, and which were addressed to a
multicast address at this sub-layer, including those that
were discarded or not sent. For a MAC layer protocol, this
includes both Group and Functional addresses.
Discontinuities in the value of this counter can occur at
re-initialization of the management system, and at other
times as indicated by the value of
ifCounterDiscontinuityTime."
::= { ifXEntry 4 }
ifOutBroadcastPkts OBJECT-TYPE
SYNTAX Counter32
MAX-ACCESS read-only
STATUS current
DESCRIPTION
"The total number of packets that higher-level protocols
requested be transmitted, and which were addressed to a
broadcast address at this sub-layer, including those that
were discarded or not sent.
Discontinuities in the value of this counter can occur at
re-initialization of the management system, and at other
McCloghrie & Kastenholz Standards Track [Page 39]
RFC 2863 The Interfaces Group MIB June 2000
times as indicated by the value of
ifCounterDiscontinuityTime."
::= { ifXEntry 5 }
--
-- High Capacity Counter objects. These objects are all
-- 64 bit versions of the "basic" ifTable counters. These
-- objects all have the same basic semantics as their 32-bit
-- counterparts, however, their syntax has been extended
-- to 64 bits.
--
ifHCInOctets OBJECT-TYPE
SYNTAX Counter64
MAX-ACCESS read-only
STATUS current
DESCRIPTION
"The total number of octets received on the interface,
including framing characters. This object is a 64-bit
version of ifInOctets.
Discontinuities in the value of this counter can occur at
re-initialization of the management system, and at other
times as indicated by the value of
ifCounterDiscontinuityTime."
::= { ifXEntry 6 }
ifHCInUcastPkts OBJECT-TYPE
SYNTAX Counter64
MAX-ACCESS read-only
STATUS current
DESCRIPTION
"The number of packets, delivered by this sub-layer to a
higher (sub-)layer, which were not addressed to a multicast
or broadcast address at this sub-layer. This object is a
64-bit version of ifInUcastPkts.
Discontinuities in the value of this counter can occur at
re-initialization of the management system, and at other
times as indicated by the value of
ifCounterDiscontinuityTime."
::= { ifXEntry 7 }
ifHCInMulticastPkts OBJECT-TYPE
SYNTAX Counter64
MAX-ACCESS read-only
STATUS current
DESCRIPTION
McCloghrie & Kastenholz Standards Track [Page 40]
RFC 2863 The Interfaces Group MIB June 2000
"The number of packets, delivered by this sub-layer to a
higher (sub-)layer, which were addressed to a multicast
address at this sub-layer. For a MAC layer protocol, this
includes both Group and Functional addresses. This object
is a 64-bit version of ifInMulticastPkts.
Discontinuities in the value of this counter can occur at
re-initialization of the management system, and at other
times as indicated by the value of
ifCounterDiscontinuityTime."
::= { ifXEntry 8 }
ifHCInBroadcastPkts OBJECT-TYPE
SYNTAX Counter64
MAX-ACCESS read-only
STATUS current
DESCRIPTION
"The number of packets, delivered by this sub-layer to a
higher (sub-)layer, which were addressed to a broadcast
address at this sub-layer. This object is a 64-bit version
of ifInBroadcastPkts.
Discontinuities in the value of this counter can occur at
re-initialization of the management system, and at other
times as indicated by the value of
ifCounterDiscontinuityTime."
::= { ifXEntry 9 }
ifHCOutOctets OBJECT-TYPE
SYNTAX Counter64
MAX-ACCESS read-only
STATUS current
DESCRIPTION
"The total number of octets transmitted out of the
interface, including framing characters. This object is a
64-bit version of ifOutOctets.
Discontinuities in the value of this counter can occur at
re-initialization of the management system, and at other
times as indicated by the value of
ifCounterDiscontinuityTime."
::= { ifXEntry 10 }
ifHCOutUcastPkts OBJECT-TYPE
SYNTAX Counter64
MAX-ACCESS read-only
STATUS current
DESCRIPTION
McCloghrie & Kastenholz Standards Track [Page 41]
RFC 2863 The Interfaces Group MIB June 2000
"The total number of packets that higher-level protocols
requested be transmitted, and which were not addressed to a
multicast or broadcast address at this sub-layer, including
those that were discarded or not sent. This object is a
64-bit version of ifOutUcastPkts.
Discontinuities in the value of this counter can occur at
re-initialization of the management system, and at other
times as indicated by the value of
ifCounterDiscontinuityTime."
::= { ifXEntry 11 }
ifHCOutMulticastPkts OBJECT-TYPE
SYNTAX Counter64
MAX-ACCESS read-only
STATUS current
DESCRIPTION
"The total number of packets that higher-level protocols
requested be transmitted, and which were addressed to a
multicast address at this sub-layer, including those that
were discarded or not sent. For a MAC layer protocol, this
includes both Group and Functional addresses. This object
is a 64-bit version of ifOutMulticastPkts.
Discontinuities in the value of this counter can occur at
re-initialization of the management system, and at other
times as indicated by the value of
ifCounterDiscontinuityTime."
::= { ifXEntry 12 }
ifHCOutBroadcastPkts OBJECT-TYPE
SYNTAX Counter64
MAX-ACCESS read-only
STATUS current
DESCRIPTION
"The total number of packets that higher-level protocols
requested be transmitted, and which were addressed to a
broadcast address at this sub-layer, including those that
were discarded or not sent. This object is a 64-bit version
of ifOutBroadcastPkts.
Discontinuities in the value of this counter can occur at
re-initialization of the management system, and at other
times as indicated by the value of
ifCounterDiscontinuityTime."
::= { ifXEntry 13 }
ifLinkUpDownTrapEnable OBJECT-TYPE
McCloghrie & Kastenholz Standards Track [Page 42]
RFC 2863 The Interfaces Group MIB June 2000
SYNTAX INTEGER { enabled(1), disabled(2) }
MAX-ACCESS read-write
STATUS current
DESCRIPTION
"Indicates whether linkUp/linkDown traps should be generated
for this interface.
By default, this object should have the value enabled(1) for
interfaces which do not operate on 'top' of any other
interface (as defined in the ifStackTable), and disabled(2)
otherwise."
::= { ifXEntry 14 }
ifHighSpeed OBJECT-TYPE
SYNTAX Gauge32
MAX-ACCESS read-only
STATUS current
DESCRIPTION
"An estimate of the interface's current bandwidth in units
of 1,000,000 bits per second. If this object reports a
value of `n' then the speed of the interface is somewhere in
the range of `n-500,000' to `n+499,999'. For interfaces
which do not vary in bandwidth or for those where no
accurate estimation can be made, this object should contain
the nominal bandwidth. For a sub-layer which has no concept
of bandwidth, this object should be zero."
::= { ifXEntry 15 }
ifPromiscuousMode OBJECT-TYPE
SYNTAX TruthValue
MAX-ACCESS read-write
STATUS current
DESCRIPTION
"This object has a value of false(2) if this interface only
accepts packets/frames that are addressed to this station.
This object has a value of true(1) when the station accepts
all packets/frames transmitted on the media. The value
true(1) is only legal on certain types of media. If legal,
setting this object to a value of true(1) may require the
interface to be reset before becoming effective.
The value of ifPromiscuousMode does not affect the reception
of broadcast and multicast packets/frames by the interface."
::= { ifXEntry 16 }
ifConnectorPresent OBJECT-TYPE
SYNTAX TruthValue
MAX-ACCESS read-only
McCloghrie & Kastenholz Standards Track [Page 43]
RFC 2863 The Interfaces Group MIB June 2000
STATUS current
DESCRIPTION
"This object has the value 'true(1)' if the interface
sublayer has a physical connector and the value 'false(2)'
otherwise."
::= { ifXEntry 17 }
ifAlias OBJECT-TYPE
SYNTAX DisplayString (SIZE(0..64))
MAX-ACCESS read-write
STATUS current
DESCRIPTION
"This object is an 'alias' name for the interface as
specified by a network manager, and provides a non-volatile
'handle' for the interface.
On the first instantiation of an interface, the value of
ifAlias associated with that interface is the zero-length
string. As and when a value is written into an instance of
ifAlias through a network management set operation, then the
agent must retain the supplied value in the ifAlias instance
associated with the same interface for as long as that
interface remains instantiated, including across all re-
initializations/reboots of the network management system,
including those which result in a change of the interface's
ifIndex value.
An example of the value which a network manager might store
in this object for a WAN interface is the (Telco's) circuit
number/identifier of the interface.
Some agents may support write-access only for interfaces
having particular values of ifType. An agent which supports
write access to this object is required to keep the value in
non-volatile storage, but it may limit the length of new
values depending on how much storage is already occupied by
the current values for other interfaces."
::= { ifXEntry 18 }
ifCounterDiscontinuityTime OBJECT-TYPE
SYNTAX TimeStamp
MAX-ACCESS read-only
STATUS current
DESCRIPTION
"The value of sysUpTime on the most recent occasion at which
any one or more of this interface's counters suffered a
discontinuity. The relevant counters are the specific
instances associated with this interface of any Counter32 or
McCloghrie & Kastenholz Standards Track [Page 44]
RFC 2863 The Interfaces Group MIB June 2000
Counter64 object contained in the ifTable or ifXTable. If
no such discontinuities have occurred since the last re-
initialization of the local management subsystem, then this
object contains a zero value."
::= { ifXEntry 19 }
-- The Interface Stack Group
--
-- Implementation of this group is optional, but strongly recommended
-- for all systems
--
ifStackTable OBJECT-TYPE
SYNTAX SEQUENCE OF IfStackEntry
MAX-ACCESS not-accessible
STATUS current
DESCRIPTION
"The table containing information on the relationships
between the multiple sub-layers of network interfaces. In
particular, it contains information on which sub-layers run
'on top of' which other sub-layers, where each sub-layer
corresponds to a conceptual row in the ifTable. For
example, when the sub-layer with ifIndex value x runs over
the sub-layer with ifIndex value y, then this table
contains:
ifStackStatus.x.y=active
For each ifIndex value, I, which identifies an active
interface, there are always at least two instantiated rows
in this table associated with I. For one of these rows, I
is the value of ifStackHigherLayer; for the other, I is the
value of ifStackLowerLayer. (If I is not involved in
multiplexing, then these are the only two rows associated
with I.)
For example, two rows exist even for an interface which has
no others stacked on top or below it:
ifStackStatus.0.x=active
ifStackStatus.x.0=active "
::= { ifMIBObjects 2 }
ifStackEntry OBJECT-TYPE
SYNTAX IfStackEntry
MAX-ACCESS not-accessible
STATUS current
McCloghrie & Kastenholz Standards Track [Page 45]
RFC 2863 The Interfaces Group MIB June 2000
DESCRIPTION
"Information on a particular relationship between two sub-
layers, specifying that one sub-layer runs on 'top' of the
other sub-layer. Each sub-layer corresponds to a conceptual
row in the ifTable."
INDEX { ifStackHigherLayer, ifStackLowerLayer }
::= { ifStackTable 1 }
IfStackEntry ::=
SEQUENCE {
ifStackHigherLayer InterfaceIndexOrZero,
ifStackLowerLayer InterfaceIndexOrZero,
ifStackStatus RowStatus
}
ifStackHigherLayer OBJECT-TYPE
SYNTAX InterfaceIndexOrZero
MAX-ACCESS not-accessible
STATUS current
DESCRIPTION
"The value of ifIndex corresponding to the higher sub-layer
of the relationship, i.e., the sub-layer which runs on 'top'
of the sub-layer identified by the corresponding instance of
ifStackLowerLayer. If there is no higher sub-layer (below
the internetwork layer), then this object has the value 0."
::= { ifStackEntry 1 }
ifStackLowerLayer OBJECT-TYPE
SYNTAX InterfaceIndexOrZero
MAX-ACCESS not-accessible
STATUS current
DESCRIPTION
"The value of ifIndex corresponding to the lower sub-layer
of the relationship, i.e., the sub-layer which runs 'below'
the sub-layer identified by the corresponding instance of
ifStackHigherLayer. If there is no lower sub-layer, then
this object has the value 0."
::= { ifStackEntry 2 }
ifStackStatus OBJECT-TYPE
SYNTAX RowStatus
MAX-ACCESS read-create
STATUS current
DESCRIPTION
McCloghrie & Kastenholz Standards Track [Page 46]
RFC 2863 The Interfaces Group MIB June 2000
"The status of the relationship between two sub-layers.
Changing the value of this object from 'active' to
'notInService' or 'destroy' will likely have consequences up
and down the interface stack. Thus, write access to this
object is likely to be inappropriate for some types of
interfaces, and many implementations will choose not to
support write-access for any type of interface."
::= { ifStackEntry 3 }
ifStackLastChange OBJECT-TYPE
SYNTAX TimeTicks
MAX-ACCESS read-only
STATUS current
DESCRIPTION
"The value of sysUpTime at the time of the last change of
the (whole) interface stack. A change of the interface
stack is defined to be any creation, deletion, or change in
value of any instance of ifStackStatus. If the interface
stack has been unchanged since the last re-initialization of
the local network management subsystem, then this object
contains a zero value."
::= { ifMIBObjects 6 }
-- Generic Receive Address Table
--
-- This group of objects is mandatory for all types of
-- interfaces which can receive packets/frames addressed to
-- more than one address.
--
-- This table replaces the ifExtnsRcvAddr table. The main
-- difference is that this table makes use of the RowStatus
-- textual convention, while ifExtnsRcvAddr did not.
ifRcvAddressTable OBJECT-TYPE
SYNTAX SEQUENCE OF IfRcvAddressEntry
MAX-ACCESS not-accessible
STATUS current
DESCRIPTION
"This table contains an entry for each address (broadcast,
multicast, or uni-cast) for which the system will receive
packets/frames on a particular interface, except as follows:
- for an interface operating in promiscuous mode, entries
are only required for those addresses for which the system
would receive frames were it not operating in promiscuous
mode.
McCloghrie & Kastenholz Standards Track [Page 47]
RFC 2863 The Interfaces Group MIB June 2000
- for 802.5 functional addresses, only one entry is
required, for the address which has the functional address
bit ANDed with the bit mask of all functional addresses for
which the interface will accept frames.
A system is normally able to use any unicast address which
corresponds to an entry in this table as a source address."
::= { ifMIBObjects 4 }
ifRcvAddressEntry OBJECT-TYPE
SYNTAX IfRcvAddressEntry
MAX-ACCESS not-accessible
STATUS current
DESCRIPTION
"A list of objects identifying an address for which the
system will accept packets/frames on the particular
interface identified by the index value ifIndex."
INDEX { ifIndex, ifRcvAddressAddress }
::= { ifRcvAddressTable 1 }
IfRcvAddressEntry ::=
SEQUENCE {
ifRcvAddressAddress PhysAddress,
ifRcvAddressStatus RowStatus,
ifRcvAddressType INTEGER
}
ifRcvAddressAddress OBJECT-TYPE
SYNTAX PhysAddress
MAX-ACCESS not-accessible
STATUS current
DESCRIPTION
"An address for which the system will accept packets/frames
on this entry's interface."
::= { ifRcvAddressEntry 1 }
ifRcvAddressStatus OBJECT-TYPE
SYNTAX RowStatus
MAX-ACCESS read-create
STATUS current
DESCRIPTION
"This object is used to create and delete rows in the
ifRcvAddressTable."
::= { ifRcvAddressEntry 2 }
ifRcvAddressType OBJECT-TYPE
SYNTAX INTEGER {
McCloghrie & Kastenholz Standards Track [Page 48]
RFC 2863 The Interfaces Group MIB June 2000
other(1),
volatile(2),
nonVolatile(3)
}
MAX-ACCESS read-create
STATUS current
DESCRIPTION
"This object has the value nonVolatile(3) for those entries
in the table which are valid and will not be deleted by the
next restart of the managed system. Entries having the
value volatile(2) are valid and exist, but have not been
saved, so that will not exist after the next restart of the
managed system. Entries having the value other(1) are valid
and exist but are not classified as to whether they will
continue to exist after the next restart."
DEFVAL { volatile }
::= { ifRcvAddressEntry 3 }
-- definition of interface-related traps.
linkDown NOTIFICATION-TYPE
OBJECTS { ifIndex, ifAdminStatus, ifOperStatus }
STATUS current
DESCRIPTION
"A linkDown trap signifies that the SNMP entity, acting in
an agent role, has detected that the ifOperStatus object for
one of its communication links is about to enter the down
state from some other state (but not from the notPresent
state). This other state is indicated by the included value
of ifOperStatus."
::= { snmpTraps 3 }
linkUp NOTIFICATION-TYPE
OBJECTS { ifIndex, ifAdminStatus, ifOperStatus }
STATUS current
DESCRIPTION
"A linkUp trap signifies that the SNMP entity, acting in an
agent role, has detected that the ifOperStatus object for
one of its communication links left the down state and
transitioned into some other state (but not into the
notPresent state). This other state is indicated by the
included value of ifOperStatus."
::= { snmpTraps 4 }
-- conformance information
McCloghrie & Kastenholz Standards Track [Page 49]
RFC 2863 The Interfaces Group MIB June 2000
ifConformance OBJECT IDENTIFIER ::= { ifMIB 2 }
ifGroups OBJECT IDENTIFIER ::= { ifConformance 1 }
ifCompliances OBJECT IDENTIFIER ::= { ifConformance 2 }
-- compliance statements
ifCompliance3 MODULE-COMPLIANCE
STATUS current
DESCRIPTION
"The compliance statement for SNMP entities which have
network interfaces."
MODULE -- this module
MANDATORY-GROUPS { ifGeneralInformationGroup,
linkUpDownNotificationsGroup }
-- The groups:
-- ifFixedLengthGroup
-- ifHCFixedLengthGroup
-- ifPacketGroup
-- ifHCPacketGroup
-- ifVHCPacketGroup
-- are mutually exclusive; at most one of these groups is implemented
-- for a particular interface. When any of these groups is implemented
-- for a particular interface, then ifCounterDiscontinuityGroup must
-- also be implemented for that interface.
GROUP ifFixedLengthGroup
DESCRIPTION
"This group is mandatory for those network interfaces which
are character-oriented or transmit data in fixed-length
transmission units, and for which the value of the
corresponding instance of ifSpeed is less than or equal to
20,000,000 bits/second."
GROUP ifHCFixedLengthGroup
DESCRIPTION
"This group is mandatory for those network interfaces which
are character-oriented or transmit data in fixed-length
transmission units, and for which the value of the
corresponding instance of ifSpeed is greater than 20,000,000
bits/second."
GROUP ifPacketGroup
DESCRIPTION
McCloghrie & Kastenholz Standards Track [Page 50]
RFC 2863 The Interfaces Group MIB June 2000
"This group is mandatory for those network interfaces which
are packet-oriented, and for which the value of the
corresponding instance of ifSpeed is less than or equal to
20,000,000 bits/second."
GROUP ifHCPacketGroup
DESCRIPTION
"This group is mandatory only for those network interfaces
which are packet-oriented and for which the value of the
corresponding instance of ifSpeed is greater than 20,000,000
bits/second but less than or equal to 650,000,000
bits/second."
GROUP ifVHCPacketGroup
DESCRIPTION
"This group is mandatory only for those network interfaces
which are packet-oriented and for which the value of the
corresponding instance of ifSpeed is greater than
650,000,000 bits/second."
GROUP ifCounterDiscontinuityGroup
DESCRIPTION
"This group is mandatory for those network interfaces that
are required to maintain counters (i.e., those for which one
of the ifFixedLengthGroup, ifHCFixedLengthGroup,
ifPacketGroup, ifHCPacketGroup, or ifVHCPacketGroup is
mandatory)."
GROUP ifRcvAddressGroup
DESCRIPTION
"The applicability of this group MUST be defined by the
media-specific MIBs. Media-specific MIBs must define the
exact meaning, use, and semantics of the addresses in this
group."
OBJECT ifLinkUpDownTrapEnable
MIN-ACCESS read-only
DESCRIPTION
"Write access is not required."
OBJECT ifPromiscuousMode
MIN-ACCESS read-only
DESCRIPTION
"Write access is not required."
OBJECT ifAdminStatus
McCloghrie & Kastenholz Standards Track [Page 51]
RFC 2863 The Interfaces Group MIB June 2000
SYNTAX INTEGER { up(1), down(2) }
MIN-ACCESS read-only
DESCRIPTION
"Write access is not required, nor is support for the value
testing(3)."
OBJECT ifAlias
MIN-ACCESS read-only
DESCRIPTION
"Write access is not required."
::= { ifCompliances 3 }
-- units of conformance
ifGeneralInformationGroup OBJECT-GROUP
OBJECTS { ifIndex, ifDescr, ifType, ifSpeed, ifPhysAddress,
ifAdminStatus, ifOperStatus, ifLastChange,
ifLinkUpDownTrapEnable, ifConnectorPresent,
ifHighSpeed, ifName, ifNumber, ifAlias,
ifTableLastChange }
STATUS current
DESCRIPTION
"A collection of objects providing information applicable to
all network interfaces."
::= { ifGroups 10 }
-- the following five groups are mutually exclusive; at most
-- one of these groups is implemented for any interface
ifFixedLengthGroup OBJECT-GROUP
OBJECTS { ifInOctets, ifOutOctets, ifInUnknownProtos,
ifInErrors, ifOutErrors }
STATUS current
DESCRIPTION
"A collection of objects providing information specific to
non-high speed (non-high speed interfaces transmit and
receive at speeds less than or equal to 20,000,000
bits/second) character-oriented or fixed-length-transmission
network interfaces."
::= { ifGroups 2 }
ifHCFixedLengthGroup OBJECT-GROUP
OBJECTS { ifHCInOctets, ifHCOutOctets,
ifInOctets, ifOutOctets, ifInUnknownProtos,
ifInErrors, ifOutErrors }
STATUS current
DESCRIPTION
McCloghrie & Kastenholz Standards Track [Page 52]
RFC 2863 The Interfaces Group MIB June 2000
"A collection of objects providing information specific to
high speed (greater than 20,000,000 bits/second) character-
oriented or fixed-length-transmission network interfaces."
::= { ifGroups 3 }
ifPacketGroup OBJECT-GROUP
OBJECTS { ifInOctets, ifOutOctets, ifInUnknownProtos,
ifInErrors, ifOutErrors,
ifMtu, ifInUcastPkts, ifInMulticastPkts,
ifInBroadcastPkts, ifInDiscards,
ifOutUcastPkts, ifOutMulticastPkts,
ifOutBroadcastPkts, ifOutDiscards,
ifPromiscuousMode }
STATUS current
DESCRIPTION
"A collection of objects providing information specific to
non-high speed (non-high speed interfaces transmit and
receive at speeds less than or equal to 20,000,000
bits/second) packet-oriented network interfaces."
::= { ifGroups 4 }
ifHCPacketGroup OBJECT-GROUP
OBJECTS { ifHCInOctets, ifHCOutOctets,
ifInOctets, ifOutOctets, ifInUnknownProtos,
ifInErrors, ifOutErrors,
ifMtu, ifInUcastPkts, ifInMulticastPkts,
ifInBroadcastPkts, ifInDiscards,
ifOutUcastPkts, ifOutMulticastPkts,
ifOutBroadcastPkts, ifOutDiscards,
ifPromiscuousMode }
STATUS current
DESCRIPTION
"A collection of objects providing information specific to
high speed (greater than 20,000,000 bits/second but less
than or equal to 650,000,000 bits/second) packet-oriented
network interfaces."
::= { ifGroups 5 }
ifVHCPacketGroup OBJECT-GROUP
OBJECTS { ifHCInUcastPkts, ifHCInMulticastPkts,
ifHCInBroadcastPkts, ifHCOutUcastPkts,
ifHCOutMulticastPkts, ifHCOutBroadcastPkts,
ifHCInOctets, ifHCOutOctets,
ifInOctets, ifOutOctets, ifInUnknownProtos,
ifInErrors, ifOutErrors,
ifMtu, ifInUcastPkts, ifInMulticastPkts,
ifInBroadcastPkts, ifInDiscards,
ifOutUcastPkts, ifOutMulticastPkts,
McCloghrie & Kastenholz Standards Track [Page 53]
RFC 2863 The Interfaces Group MIB June 2000
ifOutBroadcastPkts, ifOutDiscards,
ifPromiscuousMode }
STATUS current
DESCRIPTION
"A collection of objects providing information specific to
higher speed (greater than 650,000,000 bits/second) packet-
oriented network interfaces."
::= { ifGroups 6 }
ifRcvAddressGroup OBJECT-GROUP
OBJECTS { ifRcvAddressStatus, ifRcvAddressType }
STATUS current
DESCRIPTION
"A collection of objects providing information on the
multiple addresses which an interface receives."
::= { ifGroups 7 }
ifStackGroup2 OBJECT-GROUP
OBJECTS { ifStackStatus, ifStackLastChange }
STATUS current
DESCRIPTION
"A collection of objects providing information on the
layering of MIB-II interfaces."
::= { ifGroups 11 }
ifCounterDiscontinuityGroup OBJECT-GROUP
OBJECTS { ifCounterDiscontinuityTime }
STATUS current
DESCRIPTION
"A collection of objects providing information specific to
interface counter discontinuities."
::= { ifGroups 13 }
linkUpDownNotificationsGroup NOTIFICATION-GROUP
NOTIFICATIONS { linkUp, linkDown }
STATUS current
DESCRIPTION
"The notifications which indicate specific changes in the
value of ifOperStatus."
::= { ifGroups 14 }
-- Deprecated Definitions - Objects
--
-- The Interface Test Table
--
-- This group of objects is optional. However, a media-specific
McCloghrie & Kastenholz Standards Track [Page 54]
RFC 2863 The Interfaces Group MIB June 2000
-- MIB may make implementation of this group mandatory.
--
-- This table replaces the ifExtnsTestTable
--
ifTestTable OBJECT-TYPE
SYNTAX SEQUENCE OF IfTestEntry
MAX-ACCESS not-accessible
STATUS deprecated
DESCRIPTION
"This table contains one entry per interface. It defines
objects which allow a network manager to instruct an agent
to test an interface for various faults. Tests for an
interface are defined in the media-specific MIB for that
interface. After invoking a test, the object ifTestResult
can be read to determine the outcome. If an agent can not
perform the test, ifTestResult is set to so indicate. The
object ifTestCode can be used to provide further test-
specific or interface-specific (or even enterprise-specific)
information concerning the outcome of the test. Only one
test can be in progress on each interface at any one time.
If one test is in progress when another test is invoked, the
second test is rejected. Some agents may reject a test when
a prior test is active on another interface.
Before starting a test, a manager-station must first obtain
'ownership' of the entry in the ifTestTable for the
interface to be tested. This is accomplished with the
ifTestId and ifTestStatus objects as follows:
try_again:
get (ifTestId, ifTestStatus)
while (ifTestStatus != notInUse)
/*
* Loop while a test is running or some other
* manager is configuring a test.
*/
short delay
get (ifTestId, ifTestStatus)
}
/*
* Is not being used right now -- let's compete
* to see who gets it.
*/
lock_value = ifTestId
if ( set(ifTestId = lock_value, ifTestStatus = inUse,
McCloghrie & Kastenholz Standards Track [Page 55]
RFC 2863 The Interfaces Group MIB June 2000
ifTestOwner = 'my-IP-address') == FAILURE)
/*
* Another manager got the ifTestEntry -- go
* try again
*/
goto try_again;
/*
* I have the lock
*/
set up any test parameters.
/*
* This starts the test
*/
set(ifTestType = test_to_run);
wait for test completion by polling ifTestResult
when test completes, agent sets ifTestResult
agent also sets ifTestStatus = 'notInUse'
retrieve any additional test results, and ifTestId
if (ifTestId == lock_value+1) results are valid
A manager station first retrieves the value of the
appropriate ifTestId and ifTestStatus objects, periodically
repeating the retrieval if necessary, until the value of
ifTestStatus is 'notInUse'. The manager station then tries
to set the same ifTestId object to the value it just
retrieved, the same ifTestStatus object to 'inUse', and the
corresponding ifTestOwner object to a value indicating
itself. If the set operation succeeds then the manager has
obtained ownership of the ifTestEntry, and the value of the
ifTestId object is incremented by the agent (per the
semantics of TestAndIncr). Failure of the set operation
indicates that some other manager has obtained ownership of
the ifTestEntry.
Once ownership is obtained, any test parameters can be
setup, and then the test is initiated by setting ifTestType.
On completion of the test, the agent sets ifTestStatus to
'notInUse'. Once this occurs, the manager can retrieve the
results. In the (rare) event that the invocation of tests
by two network managers were to overlap, then there would be
a possibility that the first test's results might be
overwritten by the second test's results prior to the first
McCloghrie & Kastenholz Standards Track [Page 56]
RFC 2863 The Interfaces Group MIB June 2000
results being read. This unlikely circumstance can be
detected by a network manager retrieving ifTestId at the
same time as retrieving the test results, and ensuring that
the results are for the desired request.
If ifTestType is not set within an abnormally long period of
time after ownership is obtained, the agent should time-out
the manager, and reset the value of the ifTestStatus object
back to 'notInUse'. It is suggested that this time-out
period be 5 minutes.
In general, a management station must not retransmit a
request to invoke a test for which it does not receive a
response; instead, it properly inspects an agent's MIB to
determine if the invocation was successful. Only if the
invocation was unsuccessful, is the invocation request
retransmitted.
Some tests may require the interface to be taken off-line in
order to execute them, or may even require the agent to
reboot after completion of the test. In these
circumstances, communication with the management station
invoking the test may be lost until after completion of the
test. An agent is not required to support such tests.
However, if such tests are supported, then the agent should
make every effort to transmit a response to the request
which invoked the test prior to losing communication. When
the agent is restored to normal service, the results of the
test are properly made available in the appropriate objects.
Note that this requires that the ifIndex value assigned to
an interface must be unchanged even if the test causes a
reboot. An agent must reject any test for which it cannot,
perhaps due to resource constraints, make available at least
the minimum amount of information after that test
completes."
::= { ifMIBObjects 3 }
ifTestEntry OBJECT-TYPE
SYNTAX IfTestEntry
MAX-ACCESS not-accessible
STATUS deprecated
DESCRIPTION
"An entry containing objects for invoking tests on an
interface."
AUGMENTS { ifEntry }
::= { ifTestTable 1 }
IfTestEntry ::=
McCloghrie & Kastenholz Standards Track [Page 57]
RFC 2863 The Interfaces Group MIB June 2000
SEQUENCE {
ifTestId TestAndIncr,
ifTestStatus INTEGER,
ifTestType AutonomousType,
ifTestResult INTEGER,
ifTestCode OBJECT IDENTIFIER,
ifTestOwner OwnerString
}
ifTestId OBJECT-TYPE
SYNTAX TestAndIncr
MAX-ACCESS read-write
STATUS deprecated
DESCRIPTION
"This object identifies the current invocation of the
interface's test."
::= { ifTestEntry 1 }
ifTestStatus OBJECT-TYPE
SYNTAX INTEGER { notInUse(1), inUse(2) }
MAX-ACCESS read-write
STATUS deprecated
DESCRIPTION
"This object indicates whether or not some manager currently
has the necessary 'ownership' required to invoke a test on
this interface. A write to this object is only successful
when it changes its value from 'notInUse(1)' to 'inUse(2)'.
After completion of a test, the agent resets the value back
to 'notInUse(1)'."
::= { ifTestEntry 2 }
ifTestType OBJECT-TYPE
SYNTAX AutonomousType
MAX-ACCESS read-write
STATUS deprecated
DESCRIPTION
"A control variable used to start and stop operator-
initiated interface tests. Most OBJECT IDENTIFIER values
assigned to tests are defined elsewhere, in association with
specific types of interface. However, this document assigns
a value for a full-duplex loopback test, and defines the
special meanings of the subject identifier:
noTest OBJECT IDENTIFIER ::= { 0 0 }
When the value noTest is written to this object, no action
is taken unless a test is in progress, in which case the
test is aborted. Writing any other value to this object is
McCloghrie & Kastenholz Standards Track [Page 58]
RFC 2863 The Interfaces Group MIB June 2000
only valid when no test is currently in progress, in which
case the indicated test is initiated.
When read, this object always returns the most recent value
that ifTestType was set to. If it has not been set since
the last initialization of the network management subsystem
on the agent, a value of noTest is returned."
::= { ifTestEntry 3 }
ifTestResult OBJECT-TYPE
SYNTAX INTEGER {
none(1), -- no test yet requested
success(2),
inProgress(3),
notSupported(4),
unAbleToRun(5), -- due to state of system
aborted(6),
failed(7)
}
MAX-ACCESS read-only
STATUS deprecated
DESCRIPTION
"This object contains the result of the most recently
requested test, or the value none(1) if no tests have been
requested since the last reset. Note that this facility
provides no provision for saving the results of one test
when starting another, as could be required if used by
multiple managers concurrently."
::= { ifTestEntry 4 }
ifTestCode OBJECT-TYPE
SYNTAX OBJECT IDENTIFIER
MAX-ACCESS read-only
STATUS deprecated
DESCRIPTION
"This object contains a code which contains more specific
information on the test result, for example an error-code
after a failed test. Error codes and other values this
object may take are specific to the type of interface and/or
test. The value may have the semantics of either the
AutonomousType or InstancePointer textual conventions as
defined in RFC 2579. The identifier:
testCodeUnknown OBJECT IDENTIFIER ::= { 0 0 }
is defined for use if no additional result code is
available."
::= { ifTestEntry 5 }
McCloghrie & Kastenholz Standards Track [Page 59]
RFC 2863 The Interfaces Group MIB June 2000
ifTestOwner OBJECT-TYPE
SYNTAX OwnerString
MAX-ACCESS read-write
STATUS deprecated
DESCRIPTION
"The entity which currently has the 'ownership' required to
invoke a test on this interface."
::= { ifTestEntry 6 }
-- Deprecated Definitions - Groups
ifGeneralGroup OBJECT-GROUP
OBJECTS { ifDescr, ifType, ifSpeed, ifPhysAddress,
ifAdminStatus, ifOperStatus, ifLastChange,
ifLinkUpDownTrapEnable, ifConnectorPresent,
ifHighSpeed, ifName }
STATUS deprecated
DESCRIPTION
"A collection of objects deprecated in favour of
ifGeneralInformationGroup."
::= { ifGroups 1 }
ifTestGroup OBJECT-GROUP
OBJECTS { ifTestId, ifTestStatus, ifTestType,
ifTestResult, ifTestCode, ifTestOwner }
STATUS deprecated
DESCRIPTION
"A collection of objects providing the ability to invoke
tests on an interface."
::= { ifGroups 8 }
ifStackGroup OBJECT-GROUP
OBJECTS { ifStackStatus }
STATUS deprecated
DESCRIPTION
"The previous collection of objects providing information on
the layering of MIB-II interfaces."
::= { ifGroups 9 }
ifOldObjectsGroup OBJECT-GROUP
OBJECTS { ifInNUcastPkts, ifOutNUcastPkts,
ifOutQLen, ifSpecific }
STATUS deprecated
DESCRIPTION
McCloghrie & Kastenholz Standards Track [Page 60]
RFC 2863 The Interfaces Group MIB June 2000
"The collection of objects deprecated from the original MIB-
II interfaces group."
::= { ifGroups 12 }
-- Deprecated Definitions - Compliance
ifCompliance MODULE-COMPLIANCE
STATUS deprecated
DESCRIPTION
"A compliance statement defined in a previous version of
this MIB module, for SNMP entities which have network
interfaces."
MODULE -- this module
MANDATORY-GROUPS { ifGeneralGroup, ifStackGroup }
GROUP ifFixedLengthGroup
DESCRIPTION
"This group is mandatory for all network interfaces which
are character-oriented or transmit data in fixed-length
transmission units."
GROUP ifHCFixedLengthGroup
DESCRIPTION
"This group is mandatory only for those network interfaces
which are character-oriented or transmit data in fixed-
length transmission units, and for which the value of the
corresponding instance of ifSpeed is greater than 20,000,000
bits/second."
GROUP ifPacketGroup
DESCRIPTION
"This group is mandatory for all network interfaces which
are packet-oriented."
GROUP ifHCPacketGroup
DESCRIPTION
"This group is mandatory only for those network interfaces
which are packet-oriented and for which the value of the
corresponding instance of ifSpeed is greater than
650,000,000 bits/second."
GROUP ifTestGroup
DESCRIPTION
"This group is optional. Media-specific MIBs which require
interface tests are strongly encouraged to use this group
for invoking tests and reporting results. A medium specific
MIB which has mandatory tests may make implementation of
McCloghrie & Kastenholz Standards Track [Page 61]
RFC 2863 The Interfaces Group MIB June 2000
this group mandatory."
GROUP ifRcvAddressGroup
DESCRIPTION
"The applicability of this group MUST be defined by the
media-specific MIBs. Media-specific MIBs must define the
exact meaning, use, and semantics of the addresses in this
group."
OBJECT ifLinkUpDownTrapEnable
MIN-ACCESS read-only
DESCRIPTION
"Write access is not required."
OBJECT ifPromiscuousMode
MIN-ACCESS read-only
DESCRIPTION
"Write access is not required."
OBJECT ifStackStatus
SYNTAX INTEGER { active(1) } -- subset of RowStatus
MIN-ACCESS read-only
DESCRIPTION
"Write access is not required, and only one of the six
enumerated values for the RowStatus textual convention need
be supported, specifically: active(1)."
OBJECT ifAdminStatus
SYNTAX INTEGER { up(1), down(2) }
MIN-ACCESS read-only
DESCRIPTION
"Write access is not required, nor is support for the value
testing(3)."
::= { ifCompliances 1 }
ifCompliance2 MODULE-COMPLIANCE
STATUS deprecated
DESCRIPTION
"A compliance statement defined in a previous version of
this MIB module, for SNMP entities which have network
interfaces."
MODULE -- this module
MANDATORY-GROUPS { ifGeneralInformationGroup, ifStackGroup2,
ifCounterDiscontinuityGroup }
GROUP ifFixedLengthGroup
DESCRIPTION
McCloghrie & Kastenholz Standards Track [Page 62]
RFC 2863 The Interfaces Group MIB June 2000
"This group is mandatory for all network interfaces which
are character-oriented or transmit data in fixed-length
transmission units."
GROUP ifHCFixedLengthGroup
DESCRIPTION
"This group is mandatory only for those network interfaces
which are character-oriented or transmit data in fixed-
length transmission units, and for which the value of the
corresponding instance of ifSpeed is greater than 20,000,000
bits/second."
GROUP ifPacketGroup
DESCRIPTION
"This group is mandatory for all network interfaces which
are packet-oriented."
GROUP ifHCPacketGroup
DESCRIPTION
"This group is mandatory only for those network interfaces
which are packet-oriented and for which the value of the
corresponding instance of ifSpeed is greater than
650,000,000 bits/second."
GROUP ifRcvAddressGroup
DESCRIPTION
"The applicability of this group MUST be defined by the
media-specific MIBs. Media-specific MIBs must define the
exact meaning, use, and semantics of the addresses in this
group."
OBJECT ifLinkUpDownTrapEnable
MIN-ACCESS read-only
DESCRIPTION
"Write access is not required."
OBJECT ifPromiscuousMode
MIN-ACCESS read-only
DESCRIPTION
"Write access is not required."
OBJECT ifStackStatus
SYNTAX INTEGER { active(1) } -- subset of RowStatus
MIN-ACCESS read-only
DESCRIPTION
"Write access is not required, and only one of the six
enumerated values for the RowStatus textual convention need
be supported, specifically: active(1)."
McCloghrie & Kastenholz Standards Track [Page 63]
RFC 2863 The Interfaces Group MIB June 2000
OBJECT ifAdminStatus
SYNTAX INTEGER { up(1), down(2) }
MIN-ACCESS read-only
DESCRIPTION
"Write access is not required, nor is support for the value
testing(3)."
OBJECT ifAlias
MIN-ACCESS read-only
DESCRIPTION
"Write access is not required."
::= { ifCompliances 2 }
END
7. Acknowledgements
This memo has been produced by the IETF's Interfaces MIB working-
group.
The original proposal evolved from conversations and discussions with
many people, including at least the following: Fred Baker, Ted
Brunner, Chuck Davin, Jeremy Greene, Marshall Rose, Kaj Tesink, and
Dean Throop.
8. References
[1] Harrington, D., Presuhn, R. and B. Wijnen, "An Architecture for
Describing SNMP Management Frameworks", RFC 2571, April 1999.
[2] Rose, M. and K. McCloghrie, "Structure and Identification of
Management Information for TCP/IP-based Internets", STD 16, RFC
1155, May 1990.
[3] Rose, M. and K. McCloghrie, "Concise MIB Definitions", STD 16,
RFC 1212, March 1991.
[4] Rose, M., "A Convention for Defining Traps for use with the
SNMP", RFC 1215, March 1991.
[5] McCloghrie, K., Perkins, D., Schoenwaelder, J., Case, J., Rose,
M. and S. Waldbusser, "Structure of Management Information
Version 2 (SMIv2)", STD 58, RFC 2578, April 1999.
[6] McCloghrie, K., Perkins, D., Schoenwaelder, J., Case, J., Rose,
M. and S. Waldbusser, "Textual Conventions for SMIv2", STD 58,
RFC 2579, April 1999.
McCloghrie & Kastenholz Standards Track [Page 64]
RFC 2863 The Interfaces Group MIB June 2000
[7] McCloghrie, K., Perkins, D., Schoenwaelder, J., Case, J., Rose,
M. and S. Waldbusser, "Conformance Statements for SMIv2", STD
58, RFC 2580, April 1999.
[8] Case, J., Fedor, M., Schoffstall, M. and J. Davin, "Simple
Network Management Protocol", STD 15, RFC 1157, May 1990.
[9] Case, J., McCloghrie, K., Rose, M. and S. Waldbusser,
"Introduction to Community-based SNMPv2", RFC 1901, January
1996.
[10] Case, J., McCloghrie, K., Rose, M. and S. Waldbusser, "Transport
Mappings for Version 2 of the Simple Network Management Protocol
(SNMPv2)", RFC 1906, January 1996.
[11] Case, J., Harrington D., Presuhn R. and B. Wijnen, "Message
Processing and Dispatching for the Simple Network Management
Protocol (SNMP)", RFC 2572, January 1998.
[12] Blumenthal, U. and B. Wijnen, "User-based Security Model (USM)
for version 3 of the Simple Network Management Protocol
(SNMPv3)", RFC 2574, January 1998.
[13] Case, J., McCloghrie, K., Rose, M. and S. Waldbusser, "Protocol
Operations for Version 2 of the Simple Network Management
Protocol (SNMPv2)", RFC 1905, January 1996.
[14] Levi, D., Meyer, P. and B. Stewart, "SMPv3 Applications", RFC
2573, January 1998.
[15] Wijnen, B., Presuhn, R. and K. McCloghrie, "View-based Access
Control Model (VACM) for the Simple Network Management Protocol
(SNMP)", RFC 2575, January 1998.
[16] Bradner, S., "Key words for use in RFCs to Indicate Requirements
Levels", BCP 14, RFC 2119, March 1997.
[17] McCloghrie, K. and M. Rose, "Management Information Base for
Network Management of TCP/IP-based internets - MIB-II", STD 17.
RFC 1213, March 1991.
[18] Postel, J., "Internet Protocol", STD 5, RFC 791, September 1981.
[19] McCloghrie, K., "Extensions to the Generic-Interface MIB", RFC
1229, May 1991.
McCloghrie & Kastenholz Standards Track [Page 65]
RFC 2863 The Interfaces Group MIB June 2000
[20] ATM Forum Technical Committee, "LAN Emulation Client Management:
Version 1.0 Specification", af-lane-0044.000, ATM Forum,
September 1995.
[21] Stewart, B., "Definitions of Managed Objects for Character
Stream Devices using SMIv2", RFC 1658, July 1994.
[22] Case, J., Mundy, R., Partain, D. and B. Stewart, "Introduction
to Version 3 of the Internet-standard Network Management
Framework", RFC 2570, April 1999.
[23] McCloghrie, K. and F. Kastenholz, "Evolution of the Interfaces
Group of MIB-II", RFC 1573, January 1994.
[24] McCloghrie, K. and F. Kastenholz, "The Interfaces Group MIB
using SMIv2", RFC 2233, November 1997.
9. Security Considerations
There are a number of management objects defined in this MIB that
have a MAX-ACCESS clause of read-write and/or read-create. Such
objects may be considered sensitive or vulnerable in some network
environments. The support for SET operations in a non-secure
environment without proper protection can have a negative effect on
network operations.
In particular, write-able objects allow an administrator to control
the interfaces and to perform tests on the interfaces, and
unauthorized access to these could cause a denial of service, or in
combination with other (e.g., physical) security breaches, could
cause unauthorized connectivity to a device.
SNMPv1 by itself is not a secure environment. Even if the network
itself is secure (for example by using IPSec), even then, there is no
control as to who on the secure network is allowed to access and
GET/SET (read/change/create/delete) the objects in this MIB.
It is recommended that the implementers consider the security
features as provided by the SNMPv3 framework. Specifically, the use
of the User-based Security Model RFC 2574 [12] and the View- based
Access Control Model RFC 2575 [15] is recommended.
It is then a customer/user responsibility to ensure that the SNMP
entity giving access to an instance of this MIB, is properly
configured to give access to the objects only to those principals
(users) that have legitimate rights to indeed GET or SET
(change/create/delete) them.
McCloghrie & Kastenholz Standards Track [Page 66]
RFC 2863 The Interfaces Group MIB June 2000
10. Authors' Addresses
Keith McCloghrie
Cisco Systems, Inc.
170 West Tasman Drive
San Jose, CA 95134-1706
Phone: 408-526-5260
EMail: kzm@cisco.com"
Frank Kastenholz
Argon Networks
25 Porter Rd
Littleton Ma 01460
Phone: (508)685-4000
EMail: kasten@argon.com
11. Changes from RFC 2233
Added linkUpDownNotificationsGroup.
Changed the status of the definition of OwnerString in this MIB to be
deprecated, because it is only used by ifTestOwner, which is now
deprecated, and because other MIBs should import OwnerString from RFC
1757 or its successors.
Added ifCompliance3 as a replacement for ifCompliance2 to omit the
ifStackGroup2 group, and add linkUpDownNotificationsGroup. Also,
corrected the omission of ifVHCPacketGroup, and typos in the
DESCRIPTIONs of ifHCPacketGroup and ifFixedLengthGroup. Obsoleted
ifCompliance2.
Modified syntax of ifStackHigherLayer and ifStackLowerLayer to be
InterfaceIndexOrZero.
Added requirement that media-specific MIB designers specify any
special conditions concerning the counting of framing characters in
ifInOctets and ifOutOctets.
Corrected a typo in the DESCRIPTION of the linkUp notification.
Modified the introductory SNMP Network Management Framework
boilerplate text.
McCloghrie & Kastenholz Standards Track [Page 67]
RFC 2863 The Interfaces Group MIB June 2000
12. Notice on Intellectual Property
The IETF takes no position regarding the validity or scope of any
intellectual property or other rights that might be claimed to
pertain to the implementation or use of the technology described in
this document or the extent to which any license under such rights
might or might not be available; neither does it represent that it
has made any effort to identify any such rights. Information on the
IETF's procedures with respect to rights in standards-track and
standards-related documentation can be found in BCP-11. Copies of
claims of rights made available for publication and any assurances of
licenses to be made available, or the result of an attempt made to
obtain a general license or permission for the use of such
proprietary rights by implementors or users of this specification can
be obtained from the IETF Secretariat.
The IETF invites any interested party to bring to its attention any
copyrights, patents or patent applications, or other proprietary
rights which may cover technology that may be required to practice
this standard. Please address the information to the IETF Executive
Director.
McCloghrie & Kastenholz Standards Track [Page 68]
RFC 2863 The Interfaces Group MIB June 2000
13. Full Copyright Statement
Copyright (C) The Internet Society (2000). All Rights Reserved.
This document and translations of it may be copied and furnished to
others, and derivative works that comment on or otherwise explain it
or assist in its implementation may be prepared, copied, published
and distributed, in whole or in part, without restriction of any
kind, provided that the above copyright notice and this paragraph are
included on all such copies and derivative works. However, this
document itself may not be modified in any way, such as by removing
the copyright notice or references to the Internet Society or other
Internet organizations, except as needed for the purpose of
developing Internet standards in which case the procedures for
copyrights defined in the Internet Standards process must be
followed, or as required to translate it into languages other than
English.
The limited permissions granted above are perpetual and will not be
revoked by the Internet Society or its successors or assigns.
This document and the information contained herein is provided on an
"AS IS" basis and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING
TASK FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING
BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION
HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF
MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.
Acknowledgement
Funding for the RFC Editor function is currently provided by the
Internet Society.
McCloghrie & Kastenholz Standards Track [Page 69]