< draft-ietf-spring-bfd-03.txt   draft-ietf-spring-bfd-04.txt >
SPRING Working Group G. Mirsky SPRING Working Group G. Mirsky
Internet-Draft Ericsson Internet-Draft Ericsson
Intended status: Standards Track J. Tantsura Intended status: Standards Track J. Tantsura
Expires: 28 September 2022 Microsoft Expires: 28 October 2022 Microsoft
I. Varlashkin I. Varlashkin
Google Google
M. Chen M. Chen
Huawei Huawei
J. Wenying J. Wenying
CMCC CMCC
27 March 2022 26 April 2022
Bidirectional Forwarding Detection (BFD) in Segment Routing Networks Bidirectional Forwarding Detection (BFD) in Segment Routing Networks
Using MPLS Dataplane Using MPLS Dataplane
draft-ietf-spring-bfd-03 draft-ietf-spring-bfd-04
Abstract Abstract
Segment Routing (SR) architecture leverages the paradigm of source Segment Routing (SR) architecture leverages the paradigm of source
routing. It can be realized in the Multiprotocol Label Switching routing. It can be realized in the Multiprotocol Label Switching
(MPLS) network without any change to the data plane. A segment is (MPLS) network without any change to the data plane. A segment is
encoded as an MPLS label, and an ordered list of segments is encoded encoded as an MPLS label, and an ordered list of segments is encoded
as a stack of labels. Bidirectional Forwarding Detection (BFD) is as a stack of labels. Bidirectional Forwarding Detection (BFD) is
expected to monitor any existing path between systems. This document expected to monitor any existing path between systems. This document
defines how to use Label Switched Path Ping to bootstrap a BFD defines how to use Label Switched Path Ping to bootstrap a BFD
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Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
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This Internet-Draft will expire on 28 September 2022. This Internet-Draft will expire on 28 October 2022.
Copyright Notice Copyright Notice
Copyright (c) 2022 IETF Trust and the persons identified as the Copyright (c) 2022 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents (https://trustee.ietf.org/ Provisions Relating to IETF Documents (https://trustee.ietf.org/
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Please review these documents carefully, as they describe your rights Please review these documents carefully, as they describe your rights
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3. Use BFD Reverse Path TLV over Segment Routed MPLS Tunnel . . 5 3. Use BFD Reverse Path TLV over Segment Routed MPLS Tunnel . . 5
4. Use Non-FEC Path TLV . . . . . . . . . . . . . . . . . . . . 5 4. Use Non-FEC Path TLV . . . . . . . . . . . . . . . . . . . . 5
5. BFD Reverse Path TLV over Segment Routed MPLS Tunnel with 5. BFD Reverse Path TLV over Segment Routed MPLS Tunnel with
Dynamic Control Plane . . . . . . . . . . . . . . . . . . 7 Dynamic Control Plane . . . . . . . . . . . . . . . . . . 7
6. Applicability of BFD Demand Mode in SR-MPLS Domain . . . . . 7 6. Applicability of BFD Demand Mode in SR-MPLS Domain . . . . . 7
7. Using BFD to Monitor Point-to-Multipoint SR Policy . . . . . 8 7. Using BFD to Monitor Point-to-Multipoint SR Policy . . . . . 8
8. Use of Echo BFD in SR-MPLS . . . . . . . . . . . . . . . . . 8 8. Use of Echo BFD in SR-MPLS . . . . . . . . . . . . . . . . . 8
9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 9 9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 9
9.1. Non-FEC Path TLV . . . . . . . . . . . . . . . . . . . . 9 9.1. Non-FEC Path TLV . . . . . . . . . . . . . . . . . . . . 9
9.2. Return Code . . . . . . . . . . . . . . . . . . . . . . . 10 9.2. Return Code . . . . . . . . . . . . . . . . . . . . . . . 10
10. Implementation Status . . . . . . . . . . . . . . . . . . . . 11 10. Implementation Status . . . . . . . . . . . . . . . . . . . . 10
11. Security Considerations . . . . . . . . . . . . . . . . . . . 11 11. Security Considerations . . . . . . . . . . . . . . . . . . . 11
12. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 11 12. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 11
13. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 12 13. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 11
14. References . . . . . . . . . . . . . . . . . . . . . . . . . 12 14. References . . . . . . . . . . . . . . . . . . . . . . . . . 11
14.1. Normative References . . . . . . . . . . . . . . . . . . 12 14.1. Normative References . . . . . . . . . . . . . . . . . . 11
14.2. Informative References . . . . . . . . . . . . . . . . . 14 14.2. Informative References . . . . . . . . . . . . . . . . . 13
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 14 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 14
1. Introduction 1. Introduction
[RFC5880], [RFC5881], and [RFC5883] defined the operation of [RFC5880], [RFC5881], and [RFC5883] defined the operation of
Bidirectional Forwarding Detection (BFD) protocol between the two Bidirectional Forwarding Detection (BFD) protocol between the two
systems over IP networks. [RFC5884] and [RFC7726] set rules for systems over IP networks. [RFC5884] and [RFC7726] set rules for
using BFD Asynchronous mode over point-to-point (p2p) Multiprotocol using BFD Asynchronous mode over point-to-point (p2p) Multiprotocol
Label Switching (MPLS) Label Switched Path (LSP). These latter Label Switching (MPLS) Label Switched Path (LSP). These latter
standards implicitly assume that the remote BFD system, which is at standards implicitly assume that the remote BFD system, which is at
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detection message, i.e., BFD Control message, and the Forwarding detection message, i.e., BFD Control message, and the Forwarding
Equivalency Class (FEC) of a single label stack LSP in case of Equivalency Class (FEC) of a single label stack LSP in case of
Penultimate Hop Popping or when the egress LER distributes the Penultimate Hop Popping or when the egress LER distributes the
Explicit NULL label to the penultimate hop router. The Explicit NULL Explicit NULL label to the penultimate hop router. The Explicit NULL
label is not advertised as a Segment Identifier (SID) by an SR node label is not advertised as a Segment Identifier (SID) by an SR node
but, as demonstrated in section 3.1 [RFC8660] if the operation at the but, as demonstrated in section 3.1 [RFC8660] if the operation at the
penultimate hop is NEXT; then the egress SR node will receive an IP penultimate hop is NEXT; then the egress SR node will receive an IP
encapsulated packet. Thus the conclusion is that LSP Ping MUST be encapsulated packet. Thus the conclusion is that LSP Ping MUST be
used to bootstrap a BFD session in an SR-MPLS domain if there are no used to bootstrap a BFD session in an SR-MPLS domain if there are no
other means to bootstrap the BFD session, e.g., using an extension to other means to bootstrap the BFD session, e.g., using an extension to
a dynamic routing protocol as described in [RFC9026] and a dynamic routing protocol as described in [RFC9026] and [RFC9186].
[I-D.ietf-pim-bfd-p2mp-use-case].
As demonstrated in [RFC8287], the introduction of Segment Routing As demonstrated in [RFC8287], the introduction of Segment Routing
network domains with an MPLS data plane requires three new sub-TLVs network domains with an MPLS data plane requires three new sub-TLVs
that MAY be used with Target FEC TLV. Section 6.1 addresses the use that MAY be used with Target FEC TLV. Section 6.1 addresses the use
of the new sub-TLVs in Target FEC TLV in LSP ping and LSP traceroute. of the new sub-TLVs in Target FEC TLV in LSP ping and LSP traceroute.
For the case of LSP ping, the [RFC8287] states that: For the case of LSP ping, the [RFC8287] states that:
The initiator, i.e., ingress LER, MUST include FEC(s) The initiator, i.e., ingress LER, MUST include FEC(s)
corresponding to the destination segment. corresponding to the destination segment.
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5. BFD Reverse Path TLV over Segment Routed MPLS Tunnel with Dynamic 5. BFD Reverse Path TLV over Segment Routed MPLS Tunnel with Dynamic
Control Plane Control Plane
When Segment Routed domain with MPLS data plane uses distributed When Segment Routed domain with MPLS data plane uses distributed
tunnel computation BFD Reverse Path TLV MAY use Target FEC sub-TLVs tunnel computation BFD Reverse Path TLV MAY use Target FEC sub-TLVs
defined in [RFC8287]. defined in [RFC8287].
6. Applicability of BFD Demand Mode in SR-MPLS Domain 6. Applicability of BFD Demand Mode in SR-MPLS Domain
[I-D.mirsky-bfd-mpls-demand] defines how Demand mode of BFD, Sections 6.6 and 6.18.4 of [RFC5880] define how Demand mode of BFD
specified in sections 6.6 and 6.18.4 of [RFC5880], can be used to can be used to monitor uni-directional MPLS LSP. Similar procedures
monitor uni-directional MPLS LSP. Similar procedures can be can be following in SR-MPLS to monitor uni-directional SR tunnels:
following in SR-MPLS to monitor uni-directional SR tunnels:
* an ingress SR node bootstraps BFD session over SR-MPLS in Async * an ingress SR node bootstraps BFD session over SR-MPLS in Async
BFD mode; BFD mode;
* once BFD session is Up, the ingress SR node switches the egress * once BFD session is Up, the ingress SR node switches the egress
LER into the Demand mode by setting D field in BFD Control packet LER into the Demand mode by setting D field in BFD Control packet
it transmits; it transmits;
* if the egress LER detects the failure of the BFD session, it sends * if the egress LER detects the failure of the BFD session, it sends
its BFD Control packet to the ingress SR node over the IP network its BFD Control packet to the ingress SR node over the IP network
with a Poll sequence; with a Poll sequence;
* if the ingress SR node receives a BFD Control packet from the * if the ingress SR node receives a BFD Control packet from the
remote node in a Demand mode with Poll sequence and Diag field remote node in a Demand mode with Poll sequence and Diag field
indicating the failure, the ingress SR node transmits BFD Control indicating the failure, the ingress SR node transmits BFD Control
packet with Final over IP and switches the BFD over SR-MPLS back packet with Final over IP and switches the BFD over SR-MPLS back
into Async mode, sending BFD Control packets one per second. into Async mode, sending BFD Control packets one per second.
7. Using BFD to Monitor Point-to-Multipoint SR Policy 7. Using BFD to Monitor Point-to-Multipoint SR Policy
[I-D.voyer-spring-sr-p2mp-policy] defined variants of SR Policy to [I-D.ietf-spring-sr-replication-segment] defined variants of SR
deliver point-to-multipoint (p2mp) services. For the given P2MP Policy to deliver point-to-multipoint (p2mp) services. For the given
segment [RFC8562] can be used if, for example, leaves have an P2MP segment [RFC8562] can be used if, for example, leaves have an
alternative source of the multicast service flow to select. In such alternative source of the multicast service flow to select. In such
a scenario, a leaf may switch to using the alternative flow after a scenario, a leaf may switch to using the alternative flow after
p2mp BFD detects the failure in the working multicast path. For p2mp BFD detects the failure in the working multicast path. For
scenarios where it is required for the root to monitor the state of scenarios where it is required for the root to monitor the state of
the multicast tree [RFC8563] can be used. The root may use the the multicast tree [RFC8563] can be used. The root may use the
detection of the failure of the multicast tree to the particular leaf detection of the failure of the multicast tree to the particular leaf
to restore the path for that leaf or re-instantiate the whole to restore the path for that leaf or re-instantiate the whole
multicast tree. multicast tree.
An essential part of using p2mp BFD is the bootstrapping the BFD An essential part of using p2mp BFD is the bootstrapping the BFD
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14.1. Normative References 14.1. Normative References
[I-D.ietf-mpls-bfd-directed] [I-D.ietf-mpls-bfd-directed]
Mirsky, G., Tantsura, J., Varlashkin, I., and M. Chen, Mirsky, G., Tantsura, J., Varlashkin, I., and M. Chen,
"Bidirectional Forwarding Detection (BFD) Directed Return "Bidirectional Forwarding Detection (BFD) Directed Return
Path for MPLS Label Switched Paths (LSPs)", Work in Path for MPLS Label Switched Paths (LSPs)", Work in
Progress, Internet-Draft, draft-ietf-mpls-bfd-directed-19, Progress, Internet-Draft, draft-ietf-mpls-bfd-directed-19,
14 February 2022, <https://datatracker.ietf.org/doc/html/ 14 February 2022, <https://datatracker.ietf.org/doc/html/
draft-ietf-mpls-bfd-directed-19>. draft-ietf-mpls-bfd-directed-19>.
[I-D.mirsky-bfd-mpls-demand] [I-D.ietf-spring-sr-replication-segment]
Mirsky, G., "BFD in Demand Mode over Point-to-Point MPLS (editor), D. V., Filsfils, C., Parekh, R., Bidgoli, H.,
LSP", Work in Progress, Internet-Draft, draft-mirsky-bfd- and Z. Zhang, "SR Replication Segment for Multi-point
mpls-demand-11, 7 March 2022, Service Delivery", Work in Progress, Internet-Draft,
<https://datatracker.ietf.org/doc/html/draft-mirsky-bfd- draft-ietf-spring-sr-replication-segment-07, 7 March 2022,
mpls-demand-11>. <https://datatracker.ietf.org/doc/html/draft-ietf-spring-
sr-replication-segment-07>.
[I-D.voyer-spring-sr-p2mp-policy]
Voyer, D., Filsfils, C., Parekh, R., Bidgoli, H., and Z.
Zhang, "SR Replication Policy for P2MP Service Delivery",
Work in Progress, Internet-Draft, draft-voyer-spring-sr-
p2mp-policy-03, 2 July 2019,
<https://datatracker.ietf.org/doc/html/draft-voyer-spring-
sr-p2mp-policy-03>.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997, DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/info/rfc2119>. <https://www.rfc-editor.org/info/rfc2119>.
[RFC5880] Katz, D. and D. Ward, "Bidirectional Forwarding Detection [RFC5880] Katz, D. and D. Ward, "Bidirectional Forwarding Detection
(BFD)", RFC 5880, DOI 10.17487/RFC5880, June 2010, (BFD)", RFC 5880, DOI 10.17487/RFC5880, June 2010,
<https://www.rfc-editor.org/info/rfc5880>. <https://www.rfc-editor.org/info/rfc5880>.
skipping to change at page 14, line 23 skipping to change at page 13, line 31
<https://www.rfc-editor.org/info/rfc8563>. <https://www.rfc-editor.org/info/rfc8563>.
[RFC8660] Bashandy, A., Ed., Filsfils, C., Ed., Previdi, S., [RFC8660] Bashandy, A., Ed., Filsfils, C., Ed., Previdi, S.,
Decraene, B., Litkowski, S., and R. Shakir, "Segment Decraene, B., Litkowski, S., and R. Shakir, "Segment
Routing with the MPLS Data Plane", RFC 8660, Routing with the MPLS Data Plane", RFC 8660,
DOI 10.17487/RFC8660, December 2019, DOI 10.17487/RFC8660, December 2019,
<https://www.rfc-editor.org/info/rfc8660>. <https://www.rfc-editor.org/info/rfc8660>.
14.2. Informative References 14.2. Informative References
[I-D.ietf-pim-bfd-p2mp-use-case]
Mirsky, G. and J. Xiaoli, "Fast Failover in Protocol
Independent Multicast - Sparse Mode (PIM-SM) Using
Bidirectional Forwarding Detection (BFD) for Multipoint
Networks", Work in Progress, Internet-Draft, draft-ietf-
pim-bfd-p2mp-use-case-10, 9 December 2021,
<https://datatracker.ietf.org/doc/html/draft-ietf-pim-bfd-
p2mp-use-case-10>.
[I-D.ietf-spring-mpls-anycast-segments] [I-D.ietf-spring-mpls-anycast-segments]
Sarkar, P., Gredler, H., Filsfils, C., Previdi, S., Sarkar, P., Gredler, H., Filsfils, C., Previdi, S.,
Decraene, B., and M. Horneffer, "Anycast Segments in MPLS Decraene, B., and M. Horneffer, "Anycast Segments in MPLS
based Segment Routing", Work in Progress, Internet-Draft, based Segment Routing", Work in Progress, Internet-Draft,
draft-ietf-spring-mpls-anycast-segments-03, 27 April 2020, draft-ietf-spring-mpls-anycast-segments-03, 27 April 2020,
<https://datatracker.ietf.org/doc/html/draft-ietf-spring- <https://datatracker.ietf.org/doc/html/draft-ietf-spring-
mpls-anycast-segments-03>. mpls-anycast-segments-03>.
[RFC6790] Kompella, K., Drake, J., Amante, S., Henderickx, W., and [RFC6790] Kompella, K., Drake, J., Amante, S., Henderickx, W., and
L. Yong, "The Use of Entropy Labels in MPLS Forwarding", L. Yong, "The Use of Entropy Labels in MPLS Forwarding",
RFC 6790, DOI 10.17487/RFC6790, November 2012, RFC 6790, DOI 10.17487/RFC6790, November 2012,
<https://www.rfc-editor.org/info/rfc6790>. <https://www.rfc-editor.org/info/rfc6790>.
[RFC9026] Morin, T., Ed., Kebler, R., Ed., and G. Mirsky, Ed., [RFC9026] Morin, T., Ed., Kebler, R., Ed., and G. Mirsky, Ed.,
"Multicast VPN Fast Upstream Failover", RFC 9026, "Multicast VPN Fast Upstream Failover", RFC 9026,
DOI 10.17487/RFC9026, April 2021, DOI 10.17487/RFC9026, April 2021,
<https://www.rfc-editor.org/info/rfc9026>. <https://www.rfc-editor.org/info/rfc9026>.
[RFC9186] Mirsky, G. and X. Ji, "Fast Failover in Protocol
Independent Multicast - Sparse Mode (PIM-SM) Using
Bidirectional Forwarding Detection (BFD) for Multipoint
Networks", RFC 9186, DOI 10.17487/RFC9186, January 2022,
<https://www.rfc-editor.org/info/rfc9186>.
Authors' Addresses Authors' Addresses
Greg Mirsky Greg Mirsky
Ericsson Ericsson
Email: gregimirsky@gmail.com Email: gregimirsky@gmail.com
Jeff Tantsura Jeff Tantsura
Microsoft Microsoft
Email: jefftant.ietf@gmail.com Email: jefftant.ietf@gmail.com
Ilya Varlashkin Ilya Varlashkin
Google Google
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