IDR Working Group Z. Wang
Internet-Draft Q. Wu
Intended status: Standards Track Huawei
Expires: September 10, 2021 J. Tantsura
Juniper Networks
K. Talaulikar
Cisco Systems
March 9, 2021
Distribution of Traffic Engineering Extended Admin Groups using BGP-LS
draft-ietf-idr-eag-distribution-15
Abstract
Administrative groups are link attributes (commonly referred to as
"colors" or "link colors") advertised by link state protocols (e.g.
ISIS or OSPF) and used for traffic engineering. These administrative
groups were initially defined as 32 bit masks. As network usage
grew, these 32 bit masks were found to constrain traffic engineering.
Therefore, link state protocols (ISIS, OSPF) were expanded to
advertise a variable length administrative group.This document
defines an extension to BGP-LS for advertisement of extended
administrative groups (EAGs) to allow to support a number of
administrative groups greater than 32, as defined in [RFC7308].
Status of This Memo
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This Internet-Draft will expire on September 10, 2021.
Copyright Notice
Copyright (c) 2021 IETF Trust and the persons identified as the
document authors. All rights reserved.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
1.1. Requirements Language . . . . . . . . . . . . . . . . . . 2
2. Advertising Extended Administrative Groups in BGP-LS . . . . 3
3. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 4
4. Security Considerations . . . . . . . . . . . . . . . . . . . 4
5. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 4
6. Normative References . . . . . . . . . . . . . . . . . . . . 4
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 5
1. Introduction
Administrative groups (commonly referred to as "colors" or "link
colors") are link attributes that are advertised by link state
protocols like IS-IS [RFC5305], OSPFv2 [RFC3630] and OSPFv3 [RFC5329]
for traffic engineering use-cases. The BGP-LS advertisement of the
originally defined (non-extended) administrative groups is encoded
using the Administrative Group (color) TLV 1088 as defined in
[RFC7752].
These administrative groups are defined as a fixed-length 32-bit
bitmask. As networks grew and more use-cases were introduced, the
32-bit length was found to be constraining and hence extended
administrative groups (EAG) were introduced in the IS-IS and OSPFv2
link state routing protocols [RFC7308].
This document specifies an extension to BGP-LS for advertisement of
the extended administrative groups.
1.1. Requirements Language
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.
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2. Advertising Extended Administrative Groups in BGP-LS
This document defines an extension that enable BGP-LS speakers to
signal the EAG of links in a network to a BGP-LS consumer of network
topology such as a centralized controller. The centralized
controller can leverage this information in traffic engineering
computations and other use-cases. When a BGP-LS speaker is
originating the topology learnt via link-state routing protocols like
OSPF or IS-IS, the EAG information of the links is sourced from the
underlying extensions as defined in [RFC7308]. The BGP-LS speaker
may also advertise the EAG information for the local links of a node
when not running any link-state IGP protocol e.g. when running BGP as
the only routing protocol.
The EAG of a link is encoded in a new Link Attribute TLV [RFC7752]
using the following format:
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Extended Administrative Groups (variable) //
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 1: Extended Administrative Groups TLV Format
Where:
o Type: 1173
o Length: variable length which represents the total length of the
value field. The length value MUST be multiple of 4. If the
length is not a multiple of 4, the TLV MUST be considered
malformed.
o Value: one or more sets of 32-bit bitmasks that indicate the
administrative groups (colors) that are enabled on the link when
those specific bits are set.
The EAG TLV is an optional TLV. The originally defined AG TLV 1108
and the EAG TLV 1173 defined in this document MAY be advertised
together. The semantics of the EAG and the backward compatibility
aspects of EAG with respect to the AG are handled as described in the
Backward Compatibility section of [RFC7308], namely - If a node
advertises both AG and EAG, then the first 32 bits of the EAG MUST be
identical to the advertised AG.
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3. IANA Considerations
This document requests assigning a code-point from the registry "BGP-
LS Node Descriptor, Link Descriptor, Prefix Descriptor, and Attribute
TLVs" based on table below. Early allocation for these code-points
have been done by IANA.
+------------+-------------------------------+-------------------+
| Code Point | Description | IS-IS TLV/Sub-TLV |
+------------+-------------------------------+-------------------+
| 1173 | Extended Administrative Group | 22/14 |
+------------+-------------------------------+-------------------+
4. Security Considerations
The extensions in this document advertise same administrative group
information specified via [RFC7752] but as a larger/extended value
and hence does not introduce security issues beyond those discussed
in [RFC7752] and [I-D.ietf-idr-rfc7752bis].
5. Acknowledgments
The authors gratefully acknowledge the review by Eric Osborne and Les
Ginsberg.
6. Normative References
[I-D.ietf-idr-rfc7752bis]
Talaulikar, K., "Distribution of Link-State and Traffic
Engineering Information Using BGP", draft-ietf-idr-
rfc7752bis-05 (work in progress), November 2020.
[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>.
[RFC3630] Katz, D., Kompella, K., and D. Yeung, "Traffic Engineering
(TE) Extensions to OSPF Version 2", RFC 3630,
DOI 10.17487/RFC3630, September 2003,
<https://www.rfc-editor.org/info/rfc3630>.
[RFC5305] Li, T. and H. Smit, "IS-IS Extensions for Traffic
Engineering", RFC 5305, DOI 10.17487/RFC5305, October
2008, <https://www.rfc-editor.org/info/rfc5305>.
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[RFC5329] Ishiguro, K., Manral, V., Davey, A., and A. Lindem, Ed.,
"Traffic Engineering Extensions to OSPF Version 3",
RFC 5329, DOI 10.17487/RFC5329, September 2008,
<https://www.rfc-editor.org/info/rfc5329>.
[RFC7308] Osborne, E., "Extended Administrative Groups in MPLS
Traffic Engineering (MPLS-TE)", RFC 7308,
DOI 10.17487/RFC7308, July 2014,
<https://www.rfc-editor.org/info/rfc7308>.
[RFC7752] Gredler, H., Ed., Medved, J., Previdi, S., Farrel, A., and
S. Ray, "North-Bound Distribution of Link-State and
Traffic Engineering (TE) Information Using BGP", RFC 7752,
DOI 10.17487/RFC7752, March 2016,
<https://www.rfc-editor.org/info/rfc7752>.
[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>.
Authors' Addresses
Zitao Wang
Huawei
101 Software Avenue, Yuhua District
Nanjing, Jiangsu 210012
China
Email: wangzitao@huawei.com
Qin Wu
Huawei
101 Software Avenue, Yuhua District
Nanjing, Jiangsu 210012
China
Email: bill.wu@huawei.com
Jeff Tantsura
Juniper Networks
Email: jefftant.ietf@gmail.com
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Ketan Talaulikar
Cisco Systems
Email: ketant@cisco.com
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