Internet Engineering Task Force (IETF) B. Cheng
Request for Comments: 8757 MIT Lincoln Laboratory
Category: Standards Track L. Berger, Ed.
ISSN: 2070-1721 LabN Consulting, L.L.C.
March 2020
Dynamic Link Exchange Protocol (DLEP) Latency Range Extension
Abstract
This document defines an extension to the Dynamic Link Exchange
Protocol (DLEP) to provide the range of latency that can be
experienced on a link.
Status of This Memo
This is an Internet Standards Track document.
This document is a product of the Internet Engineering Task Force
(IETF). It represents the consensus of the IETF community. It has
received public review and has been approved for publication by the
Internet Engineering Steering Group (IESG). Further information on
Internet Standards is available in Section 2 of RFC 7841.
Information about the current status of this document, any errata,
and how to provide feedback on it may be obtained at
https://www.rfc-editor.org/info/rfc8757.
Copyright Notice
Copyright (c) 2020 IETF Trust and the persons identified as the
document authors. All rights reserved.
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Table of Contents
1. Introduction
1.1. Key Words
2. Extension Usage and Identification
3. Latency Range Data Item
4. Security Considerations
5. IANA Considerations
5.1. Extension Type Value
5.2. Data Item Value
6. References
6.1. Normative References
6.2. Informative References
Acknowledgments
Authors' Addresses
1. Introduction
The Dynamic Link Exchange Protocol (DLEP) is defined in [RFC8175].
It provides the exchange of link-related control information between
DLEP peers. DLEP peers are comprised of a modem and a router. DLEP
defines a base set of mechanisms as well as support for possible
extensions. This document defines one such extension.
The base DLEP specification includes the Latency Data Item, which
provides a single, implementation-dependent latency value on a link.
This document adds the ability to relay the minimum and maximum
latency range seen on a link. The extension defined in this document
is referred to as "Latency Range".
This document defines a new DLEP Extension Type Value that is used to
indicate the use of the extension; see Section 2. A new DLEP Data
Item is defined in Section 3.
1.1. Key Words
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in
BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all
capitals, as shown here.
2. Extension Usage and Identification
The use of the Latency Range Extension SHOULD be configurable. To
indicate that the Latency Range Extension is to be used, an
implementation MUST include the Latency Range Extension Type Value in
the Extensions Supported Data Item. The Extensions Supported Data
Item is sent and processed according to [RFC8175].
Note: The usage of the extension defined in this document does not
impact processing associated with the Latency Data Item defined in
[RFC8175].
The Latency Range Extension Type Value is 4; see Section 5.
3. Latency Range Data Item
The Latency Range Data Item serves much the same purpose as the
Latency Data Item defined in [RFC8175] with the addition of being
able to communicate the latency range that can be experienced by
traffic on a link. The Latency Range Data Item MUST be included in
the Session Initialization Response Message, with default values to
be used on a session-wide basis. The Latency Range Data Item also
MAY be carried in any message where the Latency Data Item [RFC8175]
is allowed and is carried as an additional data item. When present,
the Latency Range Data Item MUST be processed according to the same
rules as the Latency Data Item defined in [RFC8175].
The format of the Latency Range Data Item is:
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Data Item Type | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Maximum Latency :
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
: Maximum Latency |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Minimum Latency :
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
: Minimum Latency |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Data Item Type:
28
Length:
16
Maximum Latency:
A 64-bit unsigned integer, representing the longest transmission
delay, in microseconds, that a packet encounters as it is
transmitted over the link.
Minimum Latency:
A 64-bit unsigned integer, representing the shortest transmission
delay, in microseconds, that a packet can encounter as it is
transmitted over the link.
4. Security Considerations
The extension introduces a new Data Item for DLEP. The extension
does not inherently introduce any additional vulnerabilities above
those documented in [RFC8175]. The approach taken to security in
that document applies equally when running the extension defined in
this document.
5. IANA Considerations
As described below, IANA has assigned two values per this document.
Both assignments are to registries defined by [RFC8175].
5.1. Extension Type Value
IANA has assigned the following value in the "Extension Type Values"
registry within the "Dynamic Link Exchange Protocol (DLEP)
Parameters" registry. The new value is in the range with the
"Specification Required" [RFC8126] policy:
+------+---------------+
| Code | Description |
+======+===============+
| 4 | Latency Range |
+------+---------------+
Table 1: New Extension
Type Value
5.2. Data Item Value
IANA has assigned the following value in the "Data Item Type Values"
registry within the "Dynamic Link Exchange Protocol (DLEP)
Parameters" registry. The new value is in the range with the
"Specification Required" [RFC8126] policy:
+-----------+---------------+
| Type Code | Description |
+===========+===============+
| 28 | Latency Range |
+-----------+---------------+
Table 2: New Data Item Value
6. References
6.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/info/rfc2119>.
[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
May 2017, <https://www.rfc-editor.org/info/rfc8174>.
[RFC8175] Ratliff, S., Jury, S., Satterwhite, D., Taylor, R., and B.
Berry, "Dynamic Link Exchange Protocol (DLEP)", RFC 8175,
DOI 10.17487/RFC8175, June 2017,
<https://www.rfc-editor.org/info/rfc8175>.
6.2. Informative References
[RFC8126] Cotton, M., Leiba, B., and T. Narten, "Guidelines for
Writing an IANA Considerations Section in RFCs", BCP 26,
RFC 8126, DOI 10.17487/RFC8126, June 2017,
<https://www.rfc-editor.org/info/rfc8126>.
Acknowledgments
Helpful comments were received from members of the MANET working
group, including Ronald in 't Velt, Henning Rogge, and Victoria
Pritchard.
Authors' Addresses
Bow-Nan Cheng
MIT Lincoln Laboratory
Massachusetts Institute of Technology
244 Wood Street
Lexington, MA 02421-6426
United States of America
Email: bcheng@ll.mit.edu
Lou Berger (editor)
LabN Consulting, L.L.C.
Email: lberger@labn.net