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IETF RFC 8571
Last modified on Saturday, March 16th, 2019
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Internet Engineering Task Force (IETF) L. Ginsberg, Ed.
Request for Comments: 8571 Cisco Systems, Inc.
Category: Standards Track S. Previdi
ISSN: 2070-1721 Q. Wu
Huawei
J. Tantsura
Apstra, Inc.
C. Filsfils
Cisco Systems, Inc.
March 2019
BGP - Link State (BGP-LS) Advertisement of
IGP Traffic Engineering Performance Metric Extensions
 Abstract
This document defines new BGP - Link State (BGP-LS) TLVs in order to
carry the IGP Traffic Engineering Metric Extensions defined in the
IS-IS and OSPF protocols.
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/RFC 8571.
Ginsberg, et al. Standards Track PAGE 1 
RFC 8571 BGP-LS Advertisement of IGP TE Metric Extensions March 2019
Copyright Notice
Copyright (c) 2019 IETF Trust and the persons identified as the
document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents
(https://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents
carefully, as they describe your rights and restrictions with respect
to this document. Code Components extracted from this document must
include Simplified BSD License text as described in Section 4.e of
the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License.
Table of Contents
1. Introduction ....................................................2
2. Link Attribute TLVs for TE Metric Extensions ....................3
2.1. Unidirectional Link Delay TLV ..............................3
2.2. Min/Max Unidirectional Link Delay TLV ......................4
2.3. Unidirectional Delay Variation TLV .........................4
2.4. Unidirectional Link Loss TLV ...............................5
2.5. Unidirectional Residual Bandwidth TLV ......................5
2.6. Unidirectional Available Bandwidth TLV .....................6
2.7. Unidirectional Utilized Bandwidth TLV ......................6
2.8. Mappings to IGP Source Sub-TLVs ............................7
3. Security Considerations .........................................7
4. IANA Considerations .............................................8
5. References ......................................................8
5.1. Normative References .......................................8
5.2. Informative References .....................................9
Acknowledgements ...................................................9
Contributors .......................................................9
Authors' Addresses ................................................10
1. Introduction
BGP - Link State (BGP-LS) [RFC 7752] defines Network Layer
Reachability Information (NLRI) and attributes in order to carry
link-state information. New BGP-LS Link Attribute TLVs are required
in order to carry the Traffic Engineering Metric Extensions defined
in [RFC 8570] and [RFC 7471].
Ginsberg, et al. Standards Track PAGE 2
RFC 8571 BGP-LS Advertisement of IGP TE Metric Extensions March 2019
2. Link Attribute TLVs for TE Metric Extensions
The following new Link Attribute TLVs are defined:
TLV Code Point Value
--------------------------------------------------------
1114 Unidirectional Link Delay
1115 Min/Max Unidirectional Link Delay
1116 Unidirectional Delay Variation
1117 Unidirectional Link Loss
1118 Unidirectional Residual Bandwidth
1119 Unidirectional Available Bandwidth
1120 Unidirectional Utilized Bandwidth
TLV formats are described in detail in the following subsections.
TLV formats follow the rules defined in [RFC 7752].
2.1. Unidirectional Link Delay TLV
This TLV advertises the average link delay between two directly
connected IGP link-state neighbors. The semantics and values of the
fields in the TLV are described in [RFC 8570] and [RFC 7471].
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 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|A| RESERVED | Delay |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 1
where:
Type: 1114
Length: 4
Ginsberg, et al. Standards Track PAGE 3
RFC 8571 BGP-LS Advertisement of IGP TE Metric Extensions March 2019
2.2. Min/Max Unidirectional Link Delay TLV
This TLV advertises the minimum and maximum delay values between two
directly connected IGP link-state neighbors. The semantics and
values of the fields in the TLV are described in [RFC 8570] and
[RFC 7471].
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 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|A| RESERVED | Min Delay |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| RESERVED | Max Delay |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 2
where:
Type: 1115
Length: 8
2.3. Unidirectional Delay Variation TLV
This TLV advertises the average link delay variation between two
directly connected IGP link-state neighbors. The semantics and
values of the fields in the TLV are described in [RFC 8570] and
[RFC 7471].
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 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| RESERVED | Delay Variation |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 3
where:
Type: 1116
Length: 4
Ginsberg, et al. Standards Track PAGE 4
RFC 8571 BGP-LS Advertisement of IGP TE Metric Extensions March 2019
2.4. Unidirectional Link Loss TLV
This TLV advertises the loss (as a packet percentage) between two
directly connected IGP link-state neighbors. The semantics and
values of the fields in the TLV are described in [RFC 8570] and
[RFC 7471].
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 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|A| RESERVED | Link Loss |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 4
where:
Type: 1117
Length: 4
2.5. Unidirectional Residual Bandwidth TLV
This TLV advertises the residual bandwidth between two directly
connected IGP link-state neighbors. The semantics and values of the
fields in the TLV are described in [RFC 8570] and [RFC 7471].
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 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Residual Bandwidth |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 5
where:
Type: 1118
Length: 4
Ginsberg, et al. Standards Track PAGE 5
RFC 8571 BGP-LS Advertisement of IGP TE Metric Extensions March 2019
2.6. Unidirectional Available Bandwidth TLV
This TLV advertises the available bandwidth between two directly
connected IGP link-state neighbors. The semantics and values of the
fields in the TLV are described in [RFC 8570] and [RFC 7471].
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 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Available Bandwidth |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 6
where:
Type: 1119
Length: 4
2.7. Unidirectional Utilized Bandwidth TLV
This TLV advertises the bandwidth utilization between two directly
connected IGP link-state neighbors. The semantics and values of the
fields in the TLV are described in [RFC 8570] and [RFC 7471].
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 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Utilized Bandwidth |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 7
where:
Type: 1120
Length: 4
Ginsberg, et al. Standards Track PAGE 6
RFC 8571 BGP-LS Advertisement of IGP TE Metric Extensions March 2019
2.8. Mappings to IGP Source Sub-TLVs
This section documents the mappings between the Link Attribute TLVs
defined in this document and the corresponding advertisements sourced
by the IGPs.
For OSPFv2 and OSPFv3, the advertisements are defined in [RFC 7471].
For IS-IS, the advertisements are defined in [RFC 8570].
+---------------------------------------+----------+----------------+
| Attribute Name | IS-IS | OSPFv2/OSPFv3 |
| | Sub-TLV | Sub-TLV |
+---------------------------------------+----------+----------------+
| Unidirectional Link Delay | 33 | 27 |
+---------------------------------------+----------+----------------+
| Min/Max Unidirectional Link Delay | 34 | 28 |
+---------------------------------------+----------+----------------+
| Unidirectional Delay Variation | 35 | 29 |
+---------------------------------------+----------+----------------+
| Unidirectional Link Loss | 36 | 30 |
+---------------------------------------+----------+----------------+
| Unidirectional Residual Bandwidth | 37 | 31 |
+---------------------------------------+----------+----------------+
| Unidirectional Available Bandwidth | 38 | 32 |
+---------------------------------------+----------+----------------+
| Unidirectional Utilized Bandwidth | 39 | 33 |
+---------------------------------------+----------+----------------+
Figure 8
3. Security Considerations
Procedures and protocol extensions defined in this document do not
affect the BGP security model. See the "Security Considerations"
section of [RFC 4271] for a discussion of BGP security. Also, refer
to [RFC 4272] and [RFC 6952] for analyses of security issues for BGP.
Security considerations for acquiring and distributing BGP-LS
information are discussed in [RFC 7752].
The TLVs introduced in this document are used to propagate the
Traffic Engineering Metric Extensions defined in [RFC 8570] and
[RFC 7471]. These TLVs represent the state and resource availability
of the IGP link. It is assumed that the IGP instances originating
these TLVs will support all the required security and authentication
mechanisms (as described in [RFC 8570] and [RFC 7471]) in order to
prevent any security issues when propagating the TLVs into BGP-LS.
Ginsberg, et al. Standards Track PAGE 7
RFC 8571 BGP-LS Advertisement of IGP TE Metric Extensions March 2019
The advertisement of the link attribute information defined in this
document presents no additional risk beyond that associated with the
existing link attribute information already supported in [RFC 7752].
4. IANA Considerations
IANA has made assignments in the "BGP-LS Node Descriptor, Link
Descriptor, Prefix Descriptor, and Attribute TLVs" registry for the
new Link Attribute TLVs as listed below:
TLV Code Point Description
--------------------------------------------------------
1114 Unidirectional Link Delay
1115 Min/Max Unidirectional Link Delay
1116 Unidirectional Delay Variation
1117 Unidirectional Link Loss
1118 Unidirectional Residual Bandwidth
1119 Unidirectional Available Bandwidth
1120 Unidirectional Utilized Bandwidth
5. References
5.1. Normative References
[RFC 7471] Giacalone, S., Ward, D., Drake, J., Atlas, A., and S.
Previdi, "OSPF Traffic Engineering (TE) Metric
Extensions", RFC 7471, DOI 10.17487/RFC 7471, March 2015,
<https://www.rfc-editor.org/info/RFC 7471>.
[RFC 7752] 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/RFC 7752, March 2016,
<https://www.rfc-editor.org/info/RFC 7752>.
[RFC 8570] Ginsberg, L., Ed., Previdi, S., Ed., Giacalone, S., Ward,
D., Drake, J., and Q. Wu, "IS-IS Traffic Engineering (TE)
Metric Extensions", RFC 8570, DOI 10.17487/RFC 8570,
March 2019, <https://www.rfc-editor.org/info/RFC 8570>.
Ginsberg, et al. Standards Track PAGE 8
RFC 8571 BGP-LS Advertisement of IGP TE Metric Extensions March 2019
5.2. Informative References
[RFC 4271] Rekhter, Y., Ed., Li, T., Ed., and S. Hares, Ed., "A
Border Gateway Protocol 4 (BGP-4)", RFC 4271,
DOI 10.17487/RFC 4271, January 2006,
<https://www.rfc-editor.org/info/RFC 4271>.
[RFC 4272] Murphy, S., "BGP Security Vulnerabilities Analysis",
RFC 4272, DOI 10.17487/RFC 4272, January 2006,
<https://www.rfc-editor.org/info/RFC 4272>.
[RFC 6952] Jethanandani, M., Patel, K., and L. Zheng, "Analysis of
BGP, LDP, PCEP, and MSDP Issues According to the Keying
and Authentication for Routing Protocols (KARP) Design
Guide", RFC 6952, DOI 10.17487/RFC 6952, May 2013,
<https://www.rfc-editor.org/info/RFC 6952>.
Acknowledgements
The authors wish to acknowledge comments from Ketan Talaulikar.
Contributors
The following people have contributed substantially to this document
and should be considered coauthors:
Saikat Ray
Individual
Email: raysaikat@gmail.com
Hannes Gredler
RtBrick Inc.
Email: hannes@rtbrick.com
Ginsberg, et al. Standards Track PAGE 9
RFC 8571 BGP-LS Advertisement of IGP TE Metric Extensions March 2019
Authors' Addresses
Les Ginsberg (editor)
Cisco Systems, Inc.
United States of America
Email: ginsberg@cisco.com
Stefano Previdi
Huawei
Italy
Email: stefano@previdi.net
Qin Wu
Huawei
101 Software Avenue, Yuhua District
Nanjing, Jiangsu 210012
China
Email: bill.wu@huawei.com
Jeff Tantsura
Apstra, Inc.
United States of America
Email: jefftant.ietf@gmail.com
Clarence Filsfils
Cisco Systems, Inc.
Brussels
Belgium
Email: cfilsfil@cisco.com
Ginsberg, et al. Standards Track PAGE 10
RFC TOTAL SIZE: 18205 bytes
PUBLICATION DATE: Saturday, March 16th, 2019
LEGAL RIGHTS: The IETF Trust (see BCP 78)
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