Internet DRAFT - draft-ietf-spring-bfd
draft-ietf-spring-bfd
SPRING Working Group G. Mirsky
Internet-Draft Ericsson
Intended status: Standards Track J. Tantsura
Expires: 30 July 2024 NVDIA
I. Varlashkin
Google
M. Chen
Huawei
J. Wenying
CMCC
27 January 2024
Bidirectional Forwarding Detection (BFD) in Segment Routing Networks
Using MPLS Dataplane
draft-ietf-spring-bfd-09
Abstract
Segment Routing (SR) architecture leverages the paradigm of source
routing. It can be realized in the Multiprotocol Label Switching
(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
as a stack of labels. Bidirectional Forwarding Detection (BFD) is
expected to monitor any existing path between systems. This document
defines how to use Label Switched Path (LSP) Ping to bootstrap a BFD
session, optional control of the selection of a segment list as the
reverse direction of the BFD session, applicability of BFD Demand
mode, and Seamless BFD in the SR-MPLS domain. Also, the document
describes the use of the BFD Echo function with the BFD Control
packet payload.
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
working documents as Internet-Drafts. The list of current Internet-
Drafts is at https://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress."
This Internet-Draft will expire on 30 July 2024.
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Copyright Notice
Copyright (c) 2024 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 Revised BSD License text as
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provided without warranty as described in the Revised BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1. Conventions . . . . . . . . . . . . . . . . . . . . . . . 3
1.1.1. Terminology . . . . . . . . . . . . . . . . . . . . . 3
1.1.2. Requirements Language . . . . . . . . . . . . . . . . 4
2. Bootstrapping BFD Session over Segment Routed Tunnel with MPLS
Data Plane . . . . . . . . . . . . . . . . . . . . . . . 4
3. Use BFD Reverse Path TLV over Segment Routed MPLS Tunnel . . 5
4. Use Non-FEC Path TLV . . . . . . . . . . . . . . . . . . . . 5
5. BFD Reverse Path TLV over Segment Routed MPLS Tunnel with
Dynamic Control Plane . . . . . . . . . . . . . . . . . . 7
6. Applicability of BFD Demand Mode in SR-MPLS Domain . . . . . 7
7. Using BFD to Monitor Point-to-Multipoint SR Policy . . . . . 8
8. Use of Echo BFD in SR-MPLS . . . . . . . . . . . . . . . . . 8
9. Use of S-BFD in SR-MPLS . . . . . . . . . . . . . . . . . . . 9
10. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 9
10.1. Non-FEC Path TLV . . . . . . . . . . . . . . . . . . . . 9
10.2. Return Code . . . . . . . . . . . . . . . . . . . . . . 10
11. Implementation Status . . . . . . . . . . . . . . . . . . . . 11
12. Security Considerations . . . . . . . . . . . . . . . . . . . 12
13. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 12
14. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 12
15. References . . . . . . . . . . . . . . . . . . . . . . . . . 12
15.1. Normative References . . . . . . . . . . . . . . . . . . 12
15.2. Informative References . . . . . . . . . . . . . . . . . 14
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 15
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1. Introduction
[RFC5880], [RFC5881], and [RFC5883] defined the operation of
Bidirectional Forwarding Detection (BFD) protocol between the two
systems over IP networks. [RFC5884] and [RFC7726] set rules for
using BFD Asynchronous mode over point-to-point (p2p) Multiprotocol
Label Switching (MPLS) Label Switched Path (LSP). These latter
standards implicitly assume that the remote BFD system, which is at
the egress Label Edge Router (LER), will use the shortest path route
regardless of the path the BFD system at the ingress LER uses to send
BFD Control packets towards it. Throughout this document, references
to ingress LER and egress LER are used, respectively, as a shortened
version of the "BFD system at the ingress/egress LER".
This document defines the use of LSP Ping for Segment Routing
networks over the MPLS data plane [RFC8287] to bootstrap and control
path of a BFD session from the egress to ingress LER using Segment
Routing tunnel with MPLS data plane (SR-MPLS).
[RFC9256] defines the SR Policy architecture. When analyzing the
applicability of a BFD-based mechanism for detecting network failures
in a Segment Routing domain, it is essential to identify the SR
Policy elements monitored by the BFD. Concluding from the definition
of BFD in [RFC5880], in an SR domain, BFD, in its modes and
functions, monitors not the SR Policy, as defined in [RFC9256], but a
segment list that is a constituent of the candidate path of the
particular SR Policy. That is the context used throughout the
document.
1.1. Conventions
1.1.1. Terminology
BFD: Bidirectional Forwarding Detection
BSID: Binding Segment Identifier
FEC: Forwarding Equivalence Class
MPLS: Multiprotocol Label Switching
SR-MPLS Segment Routing with MPLS data plane
LSP: Label Switched Path
LER Label Edge Router
p2p Point-to-point
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p2mp Point-to-multipoint
SID Segment Identifier
SR Segment Routing
S-BFD Seamless BFD
1.1.2. 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. Bootstrapping BFD Session over Segment Routed Tunnel with MPLS Data
Plane
Use of an LSP Ping to bootstrap BFD over MPLS LSP is required, as
documented in [RFC5884], to establish an association between a fault
detection message, i.e., BFD Control message, and the Forwarding
Equivalency Class (FEC) of a single label stack LSP in case of
Penultimate Hop Popping or when the egress LER distributes the
Explicit NULL label to the penultimate hop router. The Explicit NULL
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
penultimate hop is NEXT; then the egress SR node will receive an IP
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
other means to bootstrap the BFD session, e.g., using an extension to
a dynamic routing protocol as described in [RFC9026] and [RFC9186].
As demonstrated in [RFC8287], the introduction of Segment Routing
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
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:
The initiator, i.e., ingress LER, MUST include FEC(s)
corresponding to the destination segment.
The initiator MAY include FECs corresponding to some or all of
segments imposed in the label stack by the ingress LER to
communicate the segments traversed.
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It has been noted in [RFC5884] that a BFD session monitors for
defects particular <MPLS LSP, FEC> tuple. [RFC7726] clarified how to
establish and operate multiple BFD sessions for the same <MPLS LSP,
FEC> tuple. Because only the ingress LER is aware of the SR-based
explicit route, the egress LER can associate the LSP ping with BFD
Discriminator TLV with only one of the FECs it advertised for the
particular segment. Thus this document clarifies that:
When LSP Ping is used to bootstrapping a BFD session for SR-MPLS
tunnel the FEC corresponding to the segment to be associated with
the BFD session MUST be as the very last sub-TLV in the Target FEC
TLV.
If the target segment is an anycast prefix segment
([I-D.ietf-spring-mpls-anycast-segments]) the corresponding Anycast
SID MUST be included in the Target TLV as the very last sub-TLV.
Also, for BFD Control packet the ingress SR node MUST use precisely
the same label stack encapsulation, especially Entropy Label
([RFC6790]), as for the LSP ping with the BFD Discriminator TLV that
bootstrapped the BFD session. Other operational aspects of using BFD
to monitor the continuity of the path to the particular Anycast SID,
advertised by a group of SR-MPLS capable nodes, will be considered in
the future versions of the document.
Encapsulation of a BFD Control packet in Segment Routing network with
MPLS data plane MUST follow Section 7 [RFC5884] when the IP/UDP
header used and MUST follow Section 3.4 [RFC6428] without IP/UDP
header being used.
3. Use BFD Reverse Path TLV over Segment Routed MPLS Tunnel
For BFD over MPLS LSP case, per [RFC5884], egress LER MAY send BFD
Control packet to the ingress LER either over IP network or an MPLS
LSP. Similarly, for the case of BFD over p2p SR-MPLS tunnel, the
egress LER MAY route BFD Control packet over the IP network, as
described in [RFC5883], or transmit over a segment tunnel, as
described in Section 7 [RFC5884]. In some cases, there may be a need
to direct egress LER to use a specific path for the reverse direction
of the BFD session by using the BFD Reverse Path TLV and following
all procedures as defined in [I-D.ietf-mpls-bfd-directed].
4. Use Non-FEC Path TLV
For the case of MPLS data plane, Segment Routing Architecture
[RFC8402] explains that "a segment is encoded as an MPLS label. An
ordered list of segments is encoded as a stack of labels."
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This document defines a new optional Non-FEC Path TLV. The format of
the Non-FEC Path TLV is presented in Figure 1
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Non-FEC Path TLV Type | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
~ Non-FEC Path ~
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 1: Non-FEC Path TLV Format
Non-FEC Path TLV Type is two octets in length and has a value of TBD1
(to be assigned by IANA as requested in Section 10.1).
Length field is two octets long and defines the length in octets of
the Non-FEC Path field.
Non-FEC Path field contains a sub-TLV. Any Non-FEC Path sub-TLV
(defined in this document or to be defined in the future) for Non-FEC
Path TLV type MAY be used in this field. None or one sub-TLV MAY be
included in the Non-FEC Path TLV. If no sub-TLV has been found in
the Non-FEC Path TLV, the egress LER MUST revert to using the reverse
path selected based on its local policy. If there is more than one
sub-TLV, then the Return Code in echo reply MUST be set to value TBD3
"Too Many TLVs Detected" (to be assigned by IANA as requested in
Table 4).
Non-FEC Path TLV MAY be used to specify the reverse path of the BFD
session identified in the BFD Discriminator TLV. If the Non-FEC Path
TLV is present in the echo request message the BFD Discriminator TLV
MUST be present as well. If the BFD Discriminator TLV is absent when
the Non-FEC Path TLV is included, then it MUST be treated as
malformed Echo Request, as described in [RFC8029].
This document defines the Segment Routing MPLS Tunnel sub-TLV that
MAY be used with the Non-FEC Path TLV. The format of the sub-TLV is
presented in Figure 2.
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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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| SR MPLS Tunnel sub-TLV Type | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| SID Entry 1 (Top of Stack) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| SID Entry 2 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
~ ~
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| SID Entry N (Bottom of Stack) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 2: Segment Routing MPLS Tunnel sub-TLV
The Segment Routing MPLS Tunnel sub-TLV Type is two octets in length,
and has a value of TBD2 (to be assigned by IANA as requested in
Section 10.1).
The egress LER MUST use the Value field as label stack for BFD
Control packets for the BFD session identified by the source IP
address of the MPLS LSP Ping packet and the value in the BFD
Discriminator TLV. Label Entries MUST be in network order.
5. BFD Reverse Path TLV over Segment Routed MPLS Tunnel with Dynamic
Control Plane
When Segment Routed domain with MPLS data plane uses distributed
tunnel computation BFD Reverse Path TLV MAY use Target FEC sub-TLVs
defined in [RFC8287].
6. Applicability of BFD Demand Mode in SR-MPLS Domain
Sections 6.6 and 6.18.4 of [RFC5880] define how Demand mode of BFD
can be used to monitor uni-directional MPLS LSP. Similar procedures
can be following in SR-MPLS to monitor uni-directional SR tunnels:
* an ingress SR node bootstraps BFD session over SR-MPLS in Async
BFD mode;
* 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
it transmits;
* 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
with a Poll sequence;
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* if the ingress SR node receives a BFD Control packet from the
remote node in a Demand mode with Poll sequence and Diag field
indicating the failure, the ingress SR node transmits BFD Control
packet with Final over IP and switches the BFD over SR-MPLS back
into Async mode, sending BFD Control packets one per second.
7. Using BFD to Monitor Point-to-Multipoint SR Policy
[I-D.ietf-spring-sr-replication-segment] defined variants of SR
Policy to deliver point-to-multipoint (p2mp) services. For the given
p2mp segment [RFC8562] can be used if, for example, leaves have an
alternative source of the multicast service flow to select. In such
a scenario, a leaf may switch to using the alternative flow after
p2mp BFD detects the failure in the working multicast path. For
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
detection of the failure of the multicast tree to the particular leaf
to restore the path for that leaf or re-instantiate the whole
multicast tree.
An essential part of using p2mp BFD is the bootstrapping the BFD
session at all the leaves. The root, acting as the MultipointHead,
MAY use LSP Ping with the BFD Discriminator TLV. Alternatively,
extensions to routing protocols, e.g., BGP, or management plane,
e.g., Path Computation Element Protocol, MAY be used to associate the
particular p2mp segment with MultipointHead's Discriminator.
Extensions for routing protocols and management plane are for further
study.
8. Use of Echo BFD in SR-MPLS
Echo-BFD [RFC5880] can be used to monitor a segment list of the
particular SR Policy between the local and the remote BFD peers. As
defined in [RFC5880], the remote BFD system does not process the
payload of an Echo BFD. Thus it is the local system that
demultiplexes the Echo BFD packet matching it to the appropriate BFD
session and detects missing Echo BFD packets. A BFD Control packet
MAY be used as the payload of Echo BFD. This specification defines
the use of Echo BFD in SR-MPLS network with BFD Control packet as the
payload. The use of other types of Echo BFD payload is outside the
scope of this document. Because the remote BFD system does not
process Echo BFD, the value of the Your Discriminator field MUST be
set to the discriminator the local BFD system assigned to the given
BFD session. My Discriminator field MUST be zeroed. Authentication
MUST be set according to the configuration of the BFD session. To
ensure that the Echo BFD packet is returned to the sender without
being processed, the sender MAY use a Binding SID (BSID) [RFC8402]
that has been bound with the SR Policy that ensures the return of a
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packet to that particular node. A BSID MAY be associated with the SR
Policy that is the reverse to the SR Policy programmed onto the BFD
Echo packet by the sender.
9. Use of S-BFD in SR-MPLS
Seamless BFD (S-BFD), defined in [RFC7880], maintains essential
characteristics and elements of the base BFD mechanism described in
[RFC5880] with a lighter approach to instantiating a BFD session
between BFD peers. Similar to the BFD Asynchronous mode, S-BFD is
capable of monitoring a segment list of a p2p SR Policy.
Considering that a particular SR Policy can include multiple
candidate paths, which, in turn, have one or more segment lists, it
could be beneficial to monitor each segment list independently. To
achieve that, S-BFD Reflector advertises My Discriminator value.
Then, the S-BFD Initiator uses the advertised My Discriminator value
as Your Discriminator value in the BFD Control messages transmitted
over the segment list of the SR Policy. Furthermore, the S-BFD
Initiator assigns a unique My Discriminator for each S-BFD session
monitoring a segment list. S-BFD Reflector transmits BFD Control
messages as IP/UDP packets, taking advantage of the available
resilience mechanisms of the IP network. From that point, to
minimize the detection of failures in the IP network that do not
affect the monitored segment list, it is reasonable not to use defect
detection intervals that are close to the IP network repair time.
Instead, having an S-BFD detection interval three times longer than
the IP network repair time is practical.
10. IANA Considerations
10.1. Non-FEC Path TLV
IANA is requested to assign new TLV type from the from Standards
Action range of the registry "Multiprotocol Label Switching
Architecture (MPLS) Label Switched Paths (LSPs) Ping Parameters -
TLVs" as defined in Table 1.
+=======+==================+===============+
| Value | TLV Name | Reference |
+=======+==================+===============+
| TBD1 | Non-FEC Path TLV | This document |
+-------+------------------+---------------+
Table 1: New Non-FEC Path TLV
IANA is requested to create new Non-FEC Path sub-TLV registry for the
Non-FEC Path TLV, as described in Table 2.
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+=============+===============+=====================================+
| Range | Registration | Note |
| | Procedures | |
+=============+===============+=====================================+
| 0-16383 | Standards | This range is for mandatory |
| | Action | TLVs or for optional TLVs |
| | | that require an error |
| | | message if not recognized. |
+-------------+---------------+-------------------------------------+
| 16384-31743 | Specification | Experimental RFC needed |
| | Required | |
+-------------+---------------+-------------------------------------+
| 32768-49161 | Standards | This range is for optional |
| | Action | TLVs that can be silently |
| | | dropped if not recognized. |
+-------------+---------------+-------------------------------------+
| 49162-64511 | Specification | Experimental RFC needed |
| | Required | |
+-------------+---------------+-------------------------------------+
| 64512-65535 | Private Use | |
+-------------+---------------+-------------------------------------+
Table 2: Non-FEC Path sub-TLV registry
IANA is requested to allocate the following values from the Non-FEC
Path sub-TLV registry as defined in Table 3.
+=======+=====================================+===============+
| Value | Description | Reference |
+=======+=====================================+===============+
| 0 | Reserved | This document |
+-------+-------------------------------------+---------------+
| TBD2 | Segment Routing MPLS Tunnel sub-TLV | This document |
+-------+-------------------------------------+---------------+
| 65535 | Reserved | This document |
+-------+-------------------------------------+---------------+
Table 3: New Segment Routing Tunnel sub-TLV
10.2. Return Code
IANA is requested to create Non-FEC Path sub-TLV sub-registry for the
new Non-FEC Path TLV and assign a new Return Code value from the
"Multi-Protocol Label Switching (MPLS) Label Switched Paths (LSPs)
Ping Parameters" registry, "Return Codes" sub-registry, as follows
using a Standards Action value.
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+========+=========================+===============+
| Value | Description | Reference |
+========+=========================+===============+
| X TBD3 | Too Many TLVs Detected. | This document |
+--------+-------------------------+---------------+
Table 4: New Return Code
11. Implementation Status
Note to RFC Editor: This section MUST be removed before publication
of the document.
This section records the status of known implementations of the
protocol defined by this specification at the time of posting of this
Internet-Draft, and is based on a proposal described in [RFC7942].
The description of implementations in this section is intended to
assist the IETF in its decision processes in progressing drafts to
RFCs. Please note that the listing of any individual implementation
here does not imply endorsement by the IETF. Furthermore, no effort
has been spent to verify the information presented here that was
supplied by IETF contributors. This is not intended as, and must not
be construed to be, a catalog of available implementations or their
features. Readers are advised to note that other implementations may
exist.
According to [RFC7942], "this will allow reviewers and working groups
to assign due consideration to documents that have the benefit of
running code, which may serve as evidence of valuable experimentation
and feedback that have made the implemented protocols more mature.
It is up to the individual working groups to use this information as
they see fit".
- The organization responsible for the implementation: ZTE
Corporation.
- The implementation's name ROSng SW empowers traditional routers,
e.g., ZXCTN 6000.
- A brief general description: A list of SIDs can be specified as the
Return Path for an SR-MPLS tunnel.
- The implementation's level of maturity: production.
- Coverage: complete
- Version compatibility: draft-mirsky-spring-bfd-06.
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- Licensing: proprietary.
- Implementation experience: Appreciate Early Allocation of values
for Non-FEC TLV and Segment Routing MPLS Tunnel sub-TLV (using
Private Use code points).
- Contact information: Qian Xin qian.xin2@zte.com.cn
- The date when information about this particular implementation was
last updated: 12/16/2019
12. Security Considerations
Security considerations discussed in [RFC5880], [RFC5884], [RFC7726],
and [RFC8029] apply to this document.
13. Contributors
Xiao Min
ZTE Corp.
Email: xiao.min2@zte.com.cn
14. Acknowledgments
Authors express their sincere gratitude to Alexander "Sasha"
Vainshtein for his helpful comments and thought-inspiring discussion
of SR Policies and BFD-based mechanisms. Authors greatly appreciate
the help of Qian Xin, who provided the information about the
implementation of this specification.
15. References
15.1. Normative References
[I-D.ietf-mpls-bfd-directed]
Mirsky, G., Tantsura, J., Varlashkin, I., and M. Chen,
"Bidirectional Forwarding Detection (BFD) Directed Return
Path for MPLS Label Switched Paths (LSPs)", Work in
Progress, Internet-Draft, draft-ietf-mpls-bfd-directed-25,
31 December 2023, <https://datatracker.ietf.org/doc/html/
draft-ietf-mpls-bfd-directed-25>.
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[I-D.ietf-spring-sr-replication-segment]
Voyer, D., Filsfils, C., Parekh, R., Bidgoli, H., and Z.
J. Zhang, "SR Replication segment for Multi-point Service
Delivery", Work in Progress, Internet-Draft, draft-ietf-
spring-sr-replication-segment-19, 28 August 2023,
<https://datatracker.ietf.org/doc/html/draft-ietf-spring-
sr-replication-segment-19>.
[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>.
[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>.
[RFC5881] Katz, D. and D. Ward, "Bidirectional Forwarding Detection
(BFD) for IPv4 and IPv6 (Single Hop)", RFC 5881,
DOI 10.17487/RFC5881, June 2010,
<https://www.rfc-editor.org/info/rfc5881>.
[RFC5883] Katz, D. and D. Ward, "Bidirectional Forwarding Detection
(BFD) for Multihop Paths", RFC 5883, DOI 10.17487/RFC5883,
June 2010, <https://www.rfc-editor.org/info/rfc5883>.
[RFC5884] Aggarwal, R., Kompella, K., Nadeau, T., and G. Swallow,
"Bidirectional Forwarding Detection (BFD) for MPLS Label
Switched Paths (LSPs)", RFC 5884, DOI 10.17487/RFC5884,
June 2010, <https://www.rfc-editor.org/info/rfc5884>.
[RFC6428] Allan, D., Ed., Swallow, G., Ed., and J. Drake, Ed.,
"Proactive Connectivity Verification, Continuity Check,
and Remote Defect Indication for the MPLS Transport
Profile", RFC 6428, DOI 10.17487/RFC6428, November 2011,
<https://www.rfc-editor.org/info/rfc6428>.
[RFC7726] Govindan, V., Rajaraman, K., Mirsky, G., Akiya, N., and S.
Aldrin, "Clarifying Procedures for Establishing BFD
Sessions for MPLS Label Switched Paths (LSPs)", RFC 7726,
DOI 10.17487/RFC7726, January 2016,
<https://www.rfc-editor.org/info/rfc7726>.
[RFC8029] Kompella, K., Swallow, G., Pignataro, C., Ed., Kumar, N.,
Aldrin, S., and M. Chen, "Detecting Multiprotocol Label
Switched (MPLS) Data-Plane Failures", RFC 8029,
DOI 10.17487/RFC8029, March 2017,
<https://www.rfc-editor.org/info/rfc8029>.
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[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>.
[RFC8287] Kumar, N., Ed., Pignataro, C., Ed., Swallow, G., Akiya,
N., Kini, S., and M. Chen, "Label Switched Path (LSP)
Ping/Traceroute for Segment Routing (SR) IGP-Prefix and
IGP-Adjacency Segment Identifiers (SIDs) with MPLS Data
Planes", RFC 8287, DOI 10.17487/RFC8287, December 2017,
<https://www.rfc-editor.org/info/rfc8287>.
[RFC8402] Filsfils, C., Ed., Previdi, S., Ed., Ginsberg, L.,
Decraene, B., Litkowski, S., and R. Shakir, "Segment
Routing Architecture", RFC 8402, DOI 10.17487/RFC8402,
July 2018, <https://www.rfc-editor.org/info/rfc8402>.
[RFC8562] Katz, D., Ward, D., Pallagatti, S., Ed., and G. Mirsky,
Ed., "Bidirectional Forwarding Detection (BFD) for
Multipoint Networks", RFC 8562, DOI 10.17487/RFC8562,
April 2019, <https://www.rfc-editor.org/info/rfc8562>.
[RFC8563] Katz, D., Ward, D., Pallagatti, S., Ed., and G. Mirsky,
Ed., "Bidirectional Forwarding Detection (BFD) Multipoint
Active Tails", RFC 8563, DOI 10.17487/RFC8563, April 2019,
<https://www.rfc-editor.org/info/rfc8563>.
[RFC8660] Bashandy, A., Ed., Filsfils, C., Ed., Previdi, S.,
Decraene, B., Litkowski, S., and R. Shakir, "Segment
Routing with the MPLS Data Plane", RFC 8660,
DOI 10.17487/RFC8660, December 2019,
<https://www.rfc-editor.org/info/rfc8660>.
15.2. Informative References
[I-D.ietf-spring-mpls-anycast-segments]
Sarkar, P., Gredler, H., Filsfils, C., Previdi, S.,
Decraene, B., and M. Horneffer, "Anycast Segments in MPLS
based Segment Routing", Work in Progress, Internet-Draft,
draft-ietf-spring-mpls-anycast-segments-03, 27 April 2020,
<https://datatracker.ietf.org/doc/html/draft-ietf-spring-
mpls-anycast-segments-03>.
[RFC6790] Kompella, K., Drake, J., Amante, S., Henderickx, W., and
L. Yong, "The Use of Entropy Labels in MPLS Forwarding",
RFC 6790, DOI 10.17487/RFC6790, November 2012,
<https://www.rfc-editor.org/info/rfc6790>.
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[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>.
[RFC7942] Sheffer, Y. and A. Farrel, "Improving Awareness of Running
Code: The Implementation Status Section", BCP 205,
RFC 7942, DOI 10.17487/RFC7942, July 2016,
<https://www.rfc-editor.org/info/rfc7942>.
[RFC9026] Morin, T., Ed., Kebler, R., Ed., and G. Mirsky, Ed.,
"Multicast VPN Fast Upstream Failover", RFC 9026,
DOI 10.17487/RFC9026, April 2021,
<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>.
[RFC9256] Filsfils, C., Talaulikar, K., Ed., Voyer, D., Bogdanov,
A., and P. Mattes, "Segment Routing Policy Architecture",
RFC 9256, DOI 10.17487/RFC9256, July 2022,
<https://www.rfc-editor.org/info/rfc9256>.
Authors' Addresses
Greg Mirsky
Ericsson
Email: gregimirsky@gmail.com
Jeff Tantsura
NVDIA
Email: jefftant.ietf@gmail.com
Ilya Varlashkin
Google
Email: imv@google.com
Mach(Guoyi) Chen
Huawei
Email: mach.chen@huawei.com
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Jiang Wenying
CMCC
Email: jiangwenying@chinamobile.com
Mirsky, et al. Expires 30 July 2024 [Page 16]
