Inter-Domain Routing Z. Li
Internet-Draft S. Zhuang
Intended status: Standards Track Huawei
Expires: October 30, 2022 K. Talaulikar, Ed.
Arrcus Inc
S. Aldrin
Google, Inc
J. Tantsura
Microsoft
G. Mirsky
Ericsson
April 28, 2022
BGP Link-State Extensions for Seamless BFD
draft-ietf-idr-bgp-ls-sbfd-extensions-08
Abstract
Seamless Bidirectional Forwarding Detection (S-BFD) defines a
simplified mechanism to use Bidirectional Forwarding Detection (BFD)
with large portions of negotiation aspects eliminated, thus providing
benefits such as quick provisioning as well as improved control and
flexibility to network nodes initiating the path monitoring. The
link-state routing protocols (IS-IS and OSPF) have been extended to
advertise the Seamless BFD (S-BFD) Discriminators.
This document defines extensions to the BGP Link-state address-family
to carry the S-BFD Discriminators' information via BGP.
Status of This Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute
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Drafts is at https://datatracker.ietf.org/drafts/current/.
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material or to cite them other than as "work in progress."
This Internet-Draft will expire on October 30, 2022.
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Copyright Notice
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document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
1.1. Requirements Language . . . . . . . . . . . . . . . . . . 3
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3
3. BGP-LS Extensions for S-BFD Discriminator . . . . . . . . . . 3
4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 4
5. Manageability Considerations . . . . . . . . . . . . . . . . 5
6. Security Considerations . . . . . . . . . . . . . . . . . . . 5
7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 6
8. References . . . . . . . . . . . . . . . . . . . . . . . . . 6
8.1. Normative References . . . . . . . . . . . . . . . . . . 6
8.2. Informative References . . . . . . . . . . . . . . . . . 6
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 7
1. Introduction
Seamless Bidirectional Forwarding Detection (S-BFD) [RFC7880] defines
a simplified mechanism to use Bidirectional Forwarding Detection
(BFD) [RFC5880] with large portions of negotiation aspects
eliminated, thus providing benefits such as quick provisioning as
well as improved control and flexibility to network nodes initiating
the path monitoring.
For monitoring of a service path end-to-end via S-BFD, the headend
node (i.e. Initiator) needs to know the S-BFD Discriminator of the
destination/tail-end node (i.e. Responder) of that service. The
link-state routing protocols (IS-IS [RFC7883] and OSPF [RFC7884])
have been extended to advertise the S-BFD Discriminators. With this,
an Initiator can learn the S-BFD discriminator for all Responders
within its IGP area/level, or optionally within the domain. With
networks being divided into multiple IGP domains for scaling and
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operational considerations, the service endpoints that require end to
end S-BFD monitoring often span across IGP domains.
BGP Link-State (BGP-LS) [RFC7752] enables the collection and
distribution of IGP link-state topology information via BGP sessions
across IGP areas/levels and domains. The S-BFD discriminator(s) of a
node can thus be distributed along with the topology information via
BGP-LS across IGP domains and even across multiple Autonomous Systems
(AS) within an administrative domain.
This document defines extensions to BGP-LS for carrying the S-BFD
Discriminators information.
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.
2. Terminology
This memo makes use of the terms defined in [RFC7880].
3. BGP-LS Extensions for S-BFD Discriminator
BGP-LS [RFC7752] specifies the Node NLRI for the advertisement of
nodes and their attributes using the BGP-LS Attribute. The S-BFD
discriminators of a node are considered a node-level attribute and
advertised as such.
This document defines a new BGP-LS Attribute TLV called the S-BFD
Discriminators TLV and its format is as follows:
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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 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Discriminator 1 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Discriminator 2 (Optional) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ... |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Discriminator n (Optional) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 1: S-BFD Discriminators TLV
where:
o Type: 1032 (early allocation by IANA)
o Length: variable. It MUST be a minimum of 4 octets and increments
of 4 octets for each additional discriminator.
o Discriminator n: 4 octets each, carrying an S-BFD local
discriminator value of the node. At least one discriminator MUST
be included in the TLV.
The S-BFD Discriminators TLV can be added to the BGP-LS Attribute
associated with the Node NLRI that originates the corresponding
underlying IGP TLV/sub-TLV as described below. This information is
derived from the protocol specific advertisements as follows:
o IS-IS, as defined by the S-BFD Discriminators sub-TLV in
[RFC7883].
o OSPFv2/OSPFv3, as defined by the S-BFD Discriminator TLV in
[RFC7884].
4. IANA Considerations
IANA is requested to permanently allocate the following code-point
from the "BGP-LS Node Descriptor, Link Descriptor, Prefix Descriptor,
and Attribute TLVs" registry. The column "IS-IS TLV/Sub-TLV" defined
in the registry does not require any value and should be left empty.
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+------------+--------------------------+---------------+
| Code Point | Description | Reference |
+------------+--------------------------+---------------+
| 1032 | S-BFD Discriminators TLV | This document |
+---------------+--------------------------+------------+
Table 1: S-BFD Discriminators TLV Code-Point Allocation
5. Manageability Considerations
The new protocol extensions introduced in this document augment the
existing IGP topology information that was distributed via BGP-LS
[RFC7752]. Procedures and protocol extensions defined in this
document do not affect the BGP protocol operations and management
other than as discussed in the Manageability Considerations section
of [RFC7752]. Specifically, the malformed NLRIs attribute tests in
the Fault Management section of [RFC7752] now encompass the new TLV
for the BGP-LS NLRI in this document.
6. Security Considerations
The new protocol extensions introduced in this document augment the
existing IGP topology information that can be distributed via BGP-LS
[RFC7752]. Procedures and protocol extensions defined in this
document do not affect the BGP security model other than as discussed
in the Security Considerations section of [RFC7752]. More
specifically, the aspects related to limiting the nodes and consumers
with which the topology information is shared via BGP-LS to trusted
entities within an administrative domain.
The TLV introduced in this document is used to propagate IGP defined
information ([RFC7883] and [RFC7883]). The TLV represents
information used to set up S-BFD sessions. The IGP instances
originating this information are assumed to support any required
security and authentication mechanisms (as described in [RFC7883] and
[RFC7883]) to prevent any security issues when propagating the
information into BGP-LS.
Advertising the S-BFD Discriminators via BGP-LS makes it possible for
attackers to initiate S-BFD sessions using the advertised
information. The vulnerabilities this poses and how to mitigate them
are discussed in [RFC7880].
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7. Acknowledgements
The authors would like to thank Nan Wu for his contributions to this
work. The authors would also like to thank Gunter Van De Velde and
Thomas Fossati for their reviews. The authors would also like to
thank Jeff Haas for his shepherd review and Alvaro Retana for his AD
review of this document.
8. References
8.1. 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>.
[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>.
[RFC7880] Pignataro, C., Ward, D., Akiya, N., Bhatia, M., and S.
Pallagatti, "Seamless Bidirectional Forwarding Detection
(S-BFD)", RFC 7880, DOI 10.17487/RFC7880, July 2016,
<https://www.rfc-editor.org/info/rfc7880>.
[RFC7883] Ginsberg, L., Akiya, N., and M. Chen, "Advertising
Seamless Bidirectional Forwarding Detection (S-BFD)
Discriminators in IS-IS", RFC 7883, DOI 10.17487/RFC7883,
July 2016, <https://www.rfc-editor.org/info/rfc7883>.
[RFC7884] Pignataro, C., Bhatia, M., Aldrin, S., and T. Ranganath,
"OSPF Extensions to Advertise Seamless Bidirectional
Forwarding Detection (S-BFD) Target Discriminators",
RFC 7884, DOI 10.17487/RFC7884, July 2016,
<https://www.rfc-editor.org/info/rfc7884>.
[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>.
8.2. Informative References
[RFC5880] Katz, D. and D. Ward, "Bidirectional Forwarding Detection
(BFD)", RFC 5880, DOI 10.17487/RFC5880, June 2010,
<https://www.rfc-editor.org/info/rfc5880>.
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Authors' Addresses
Zhenbin Li
Huawei
Huawei Bld., No.156 Beiqing Rd.
Beijing 100095
China
Email: lizhenbin@huawei.com
Shunwan Zhuang
Huawei
Huawei Bld., No.156 Beiqing Rd.
Beijing 100095
China
Email: zhuangshunwan@huawei.com
Ketan Talaulikar (editor)
Arrcus Inc
India
Email: ketant.ietf@gmail.com
Sam Aldrin
Google, Inc
Email: aldrin.ietf@gmail.com
Jeff Tantsura
Microsoft
Email: jefftant.ietf@gmail.com
Greg Mirsky
Ericsson
Email: gregimirsky@gmail.com
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