RFC 8571 PROPOSED STANDARD ROUTING · BGP · TRAFFIC ENGINEERING
BGP-LS TE Performance: BGP - Link State (BGP-LS) Advertisement of IGP Traffic Engineering Performance Metric Extensions
Seven new BGP-LS attributes that carry link delay, loss and bandwidth measurements to a controller.
RFC EDITOR
Ginsberg, L., Ed., Previdi, S., Wu, Q., Tantsura, J., and C. Filsfils, "BGP - Link State (BGP-LS) Advertisement of IGP Traffic Engineering Performance Metric Extensions", RFC 8571, DOI 10.17487/RFC8571, March 2019, <https://www.rfc-editor.org/info/rfc8571>.
BIBTEX
@misc{rfc8571,
series = {Request for Comments},
number = 8571,
howpublished = {RFC 8571},
publisher = {RFC Editor},
doi = {10.17487/RFC8571},
url = {https://www.rfc-editor.org/info/rfc8571},
author = {L. Ginsberg and S. Previdi and Q. Wu and J. Tantsura and C. Filsfils},
title = {{BGP - Link State (BGP-LS) Advertisement of IGP Traffic Engineering Performance Metric Extensions}},
pagetotal = 10,
year = 2019,
month = mar,
} RFC text
Contents
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/rfc8571.
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) [RFC7752] 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 [RFC8570] and [RFC7471].
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 [RFC7752].
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 [RFC8570] and [RFC7471].
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
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 [RFC8570] and
[RFC7471].
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 [RFC8570] and
[RFC7471].
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
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 [RFC8570] and
[RFC7471].
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 [RFC8570] and [RFC7471].
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
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 [RFC8570] and [RFC7471].
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 [RFC8570] and [RFC7471].
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
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 [RFC7471].
For IS-IS, the advertisements are defined in [RFC8570].
+---------------------------------------+----------+----------------+
| 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 [RFC4271] for a discussion of BGP security. Also, refer
to [RFC4272] and [RFC6952] for analyses of security issues for BGP.
Security considerations for acquiring and distributing BGP-LS
information are discussed in [RFC7752].
The TLVs introduced in this document are used to propagate the
Traffic Engineering Metric Extensions defined in [RFC8570] and
[RFC7471]. 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 [RFC8570] and [RFC7471]) in order to
prevent any security issues when propagating the TLVs into BGP-LS.
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 [RFC7752].
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
[RFC7471] Giacalone, S., Ward, D., Drake, J., Atlas, A., and S.
Previdi, "OSPF Traffic Engineering (TE) Metric
Extensions", RFC 7471, DOI 10.17487/RFC7471, March 2015,
<https://www.rfc-editor.org/info/rfc7471>.
[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>.
[RFC8570] 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/RFC8570,
March 2019, <https://www.rfc-editor.org/info/rfc8570>.
5.2. Informative References
[RFC4271] Rekhter, Y., Ed., Li, T., Ed., and S. Hares, Ed., "A
Border Gateway Protocol 4 (BGP-4)", RFC 4271,
DOI 10.17487/RFC4271, January 2006,
<https://www.rfc-editor.org/info/rfc4271>.
[RFC4272] Murphy, S., "BGP Security Vulnerabilities Analysis",
RFC 4272, DOI 10.17487/RFC4272, January 2006,
<https://www.rfc-editor.org/info/rfc4272>.
[RFC6952] 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/RFC6952, May 2013,
<https://www.rfc-editor.org/info/rfc6952>.
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
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
AI ELI5
On this page
PROBLEMIS-IS and OSPF can advertise link performance measurements, but BGP-LS had no way to carry them to systems outside the IGP.
MECHANISMThe RFC defines seven new BGP-LS Link Attribute TLVs, with code points 1114 to 1120, for delay, min/max delay, delay variation, loss, and residual, available and utilized bandwidth.
WHY IT MATTERSBGP-LS can now distribute the IGP Traffic Engineering Metric Extensions. IANA has assigned the seven code points.
§1Introduction
BGP - Link State (BGP-LS), defined in RFC 7752, defines NLRI and attributes for carrying link-state information in BGP. To carry the Traffic Engineering Metric Extensions of RFC 8570 (IS-IS) and RFC 7471 (OSPF), new BGP-LS Link Attribute TLVs are needed. This document defines them.
A TLV is a type, length, value record. The semantics and values of the fields inside each new TLV are not redefined here; they are described in RFC 8570 and RFC 7471.
Routers already have a way to tell a planner about their links. This adds new kinds of notes to that channel, such as how fast and how full a link is.
§2The Seven Link Attribute TLVs
Each TLV describes a measurement between two directly connected IGP link-state neighbors, and each follows the TLV rules of RFC 7752. The new TLVs are:
- Unidirectional Link Delay (1114): the average link delay.
- Min/Max Unidirectional Link Delay (1115): the minimum and maximum delay values.
- Unidirectional Delay Variation (1116): the average delay variation.
- Unidirectional Link Loss (1117): loss as a packet percentage.
- Unidirectional Residual Bandwidth (1118).
- Unidirectional Available Bandwidth (1119).
- Unidirectional Utilized Bandwidth (1120): the bandwidth utilization.
The delay TLV has a Type of 1114 and a Length of 4. Its value has an A bit, a reserved field and a Delay field. The Min/Max TLV has Length 8 and carries both a Min Delay and a Max Delay. The delay variation, loss and bandwidth TLVs each have Length 4.
There is one labeled box for each thing a router can measure about a link: how long it takes, how much it wobbles, how much gets lost, and how much room is left.
- 1114Unidirectional Link Delay — Average link delay.
- 1115Min/Max Unidirectional Link Delay — Minimum and maximum delay.
- 1116Unidirectional Delay Variation — Average delay variation.
- 1117Unidirectional Link Loss — Loss as a packet percentage.
- 1118Unidirectional Residual Bandwidth — Residual bandwidth.
- 1119Unidirectional Available Bandwidth — Available bandwidth.
- 1120Unidirectional Utilized Bandwidth — Bandwidth utilization.
| Field | Name | Size | Value | Description |
|---|---|---|---|---|
TYPE | Type | 2 bytes | 1114 | TLV type. |
LENGTH | Length | 2 bytes | 4 | Length of the value. |
A | A | 1 bits | Flag bit; its meaning is given in RFC 8570 and RFC 7471. | |
RESERVED | RESERVED | 7 bits | Reserved. | |
DELAY | Delay | 3 bytes | Delay value, as described in RFC 8570 and RFC 7471. |
§3Mapping to IGP Sub-TLVs
Each new BGP-LS TLV corresponds to an advertisement sourced by the IGPs. For OSPFv2 and OSPFv3 these are defined in RFC 7471; for IS-IS they are defined in RFC 8570. For example, Unidirectional Link Delay is IS-IS sub-TLV 33 and OSPF sub-TLV 27. The table in the RFC runs from IS-IS sub-TLVs 33 to 39 and OSPF sub-TLVs 27 to 33, in the same order as the TLV list.
Each new box matches a box that routers already use at home, so the number just gets copied into the shared channel.
| Attribute | IS-IS sub-TLV | OSPFv2/OSPFv3 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 |
§4Security Considerations
The procedures and extensions do not affect the BGP security model. The RFC points to RFC 4271, RFC 4272 and RFC 6952 for BGP security, and to RFC 7752 for BGP-LS information.
The TLVs represent the state and resource availability of the IGP link. It is assumed that the IGP instances originating them support the security and authentication mechanisms of RFC 8570 and RFC 7471. Advertising this information presents no additional risk beyond the link attribute information already supported in RFC 7752.
Sharing these numbers is no riskier than sharing what the channel already carries, as long as the routers that make them are protected.
§5IANA Considerations
IANA has made assignments in the 'BGP-LS Node Descriptor, Link Descriptor, Prefix Descriptor, and Attribute TLVs' registry for the seven new Link Attribute TLVs, using code points 1114 through 1120 as listed in the RFC.
An official list of box numbers was updated so that everyone uses the same number for the same kind of box.
§6References
[RFC7471]RFC 7471Giacalone, S., et al., "OSPF Traffic Engineering (TE) Metric Extensions", RFC 7471, March 2015.March 2015[RFC7752]RFC 7752Gredler, H., Ed., et al., "North-Bound Distribution of Link-State and Traffic Engineering (TE) Information Using BGP", RFC 7752, March 2016.March 2016[RFC8570]RFC 8570Ginsberg, L., Ed., et al., "IS-IS Traffic Engineering (TE) Metric Extensions", RFC 8570, March 2019.March 2019[RFC4271]RFC 4271Rekhter, Y., Ed., Li, T., Ed., and S. Hares, Ed., "A Border Gateway Protocol 4 (BGP-4)", RFC 4271, January 2006.January 2006[RFC4272]RFC 4272Murphy, S., "BGP Security Vulnerabilities Analysis", RFC 4272, January 2006.January 2006[RFC6952]RFC 6952Jethanandani, 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, May 2013.May 2013