MPLS Working Group
Internet Engineering Task Force (IETF) G. Mirsky
Internet-Draft
Request for Comments: 9780 Ericsson
Updates: 8562 (if approved) G. Mishra
Intended status:
Category: Standards Track Verizon Inc.
Expires: 23 August 2025
ISSN: 2070-1721 D. Eastlake 3rd
Independent
19 February
May 2025
Bidirectional Forwarding Detection (BFD) for Multipoint Networks over
Point-to-Multi-Point
Point-to-Multipoint MPLS Label Switched Path (LSP)
draft-ietf-mpls-p2mp-bfd-11 Paths (LSPs)
Abstract
This document describes procedures for using Bidirectional Forwarding
Detection (BFD) for multipoint networks to detect data plane failures
in Multiprotocol Label Switching (MPLS) MPLS point-to-multipoint Label Switched Paths (LSPs) and Segment
Routing (SR) point-to-multipoint policies with an SR over MPLS (SR-
MPLS) data plane.
Furthermore, this document also updates RFC 8562 and recommends by recommending the use
of an IPv6 address from the Dummy IPv6 Prefix range TBA2/64
(Section 7.1) 100:0:0:1::/64
and discourages discouraging the use of an IPv4 loopback address mapped to IPv6.
It also
In addition, this document describes the applicability of LSP Ping,
as in-band, and the control plane, as out-band, out-of-band, solutions to
bootstrap a BFD session.
It The document also describes the behavior of
the active tail for head notification.
Status of This Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
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(IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list It represents the consensus of current Internet-
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Internet-Drafts are draft documents valid the IETF community. It has
received public review and has been approved for a maximum publication by the
Internet Engineering Steering Group (IESG). Further information on
Internet Standards is available in Section 2 of six months RFC 7841.
Information about the current status of this document, any errata,
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material or to cite them other than as "work in progress."
This Internet-Draft will expire on 23 August 2025.
https://www.rfc-editor.org/info/rfc9780.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Conventions used Used in this document . . . . . . . . . . . . . . 3 This Document
2.1. Terminology . . . . . . . . . . . . . . . . . . . . . . . 3
2.2. Requirements Language . . . . . . . . . . . . . . . . . . 4
3. Multipoint BFD Encapsulation . . . . . . . . . . . . . . . . 4
3.1. IP Encapsulation of Multipoint BFD . . . . . . . . . . . 4
3.2. Non-IP Encapsulation of Multipoint BFD . . . . . . . . . 5
4. Bootstrapping Multipoint BFD . . . . . . . . . . . . . . . . 6
4.1. LSP Ping . . . . . . . . . . . . . . . . . . . . . . . . 6
4.2. Control Plane . . . . . . . . . . . . . . . . . . . . . . 7
5. Operation of Multipoint BFD with Active Tail over P2MP MPLS LSP . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
6. Security Considerations . . . . . . . . . . . . . . . . . . . 9
7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 9
7.1. IPv6 Special-Purpose Address Allocation . . . . . . . . . . . . . . . . . 10
7.2. Multipoint BFD over MPLS LSP Generalized Associated Channel (G-ACh) Type . . 10
8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 10
9. References . . . . . . . . . . . . . . . . . . . . . . . . . 10
9.1.
8.1. Normative References . . . . . . . . . . . . . . . . . . 10
9.2.
8.2. Informative References . . . . . . . . . . . . . . . . . 12
Acknowledgements
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 13
1. Introduction
[RFC8562] defines a method of using Bidirectional Forwarding
Detection (BFD) [RFC5880] to monitor and detect failures between the
sender (head) and one or more receivers (tails) in multipoint or
multicast networks.
[RFC8562] added two BFD session types - types: MultipointHead and
MultipointTail. Throughout this document, MultipointHead and
MultipointTail refer to the value to which the bfd.SessionType is set
on a BFD endpoint.
This document describes procedures for using such modes of the BFD
protocol to detect data plane failures in Multiprotocol Label
Switching (MPLS) MPLS point-to-multipoint (p2mp)
(P2MP) Label Switched Paths (LSPs) and Segment Routing (SR) point-to-multipoint point-to-
multipoint policies with an SR over MPLS (SR-MPLS) data plane plane.
The document also describes the applicability of out-band out-of-band
solutions to bootstrap a BFD session in this environment.
Historically, an IPv6-mapped IPv4 loopback range
address::ffff:127.0.0.1/128 was mandated, although functionally, an
IPv6 address from that range is not analogous to its IPv4
counterpart. Furthermore, using the loopback address as the
destination address, even for an inner IP encapsulation of a tunneled
packet
packet, violates Section 2.5.3 of [RFC4291]. Hence, IANA is requested
to allocate TBA2/64 has
allocated 100:0:0:1::/64 as a new Dummy IPv6 Prefix (Section 7.1) to
select destination IPv6 addresses for IP/UDP encapsulation of
management, control, and OAM Operations, Administration, and Maintenance
(OAM) packets. A source-only IPv6 dummy address is used as the
destination to generate an exception and a reply message to the
request message received. This draft document starts the transition to
using the IPv6 addresses from the Dummy IPv6 Prefix range TBA2/64
100:0:0:1::/64 as the IPv6 destination address in the IP/UDP
encapsulation of active OAM over the MPLS data plane. Thus, this
document also updates [RFC8562] and recommends by recommending the use of an IPv6 address
from the Dummy IPv6 Prefix range TBA2/64 100:0:0:1::/64 (Section 7.1) while
acknowledging that an address from the ::ffff:127.0.0.1/128 range
might be used by existing implementations, implementations. This document discourages
the use of an address in the IPv6-mapped IPv4 loopback range address.
It range.
This document also describes the behavior of the active tail for head
notification.
2. Conventions used Used in this document This Document
2.1. Terminology
ACH: Associated Channel Header
BFD: Bidirectional Forwarding Detection
GAL: G-ACh Label
G-ACh: Generic Associated Channel
LSP: Label Switched Path
LSR: Label Switching Router
MPLS: Multiprotocol Label Switching
p2mp:
P2MP: Point-to-Multipoint
PW: Pseudowire (PW)
SR: Segment Routing
SR-MPLS: SR over MPLS
2.2. 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.
3. Multipoint BFD Encapsulation
[RFC8562] uses BFD in the Demand mode from the very start of a point-
to-multipoint (p2mp) point-to-
multipoint (P2MP) BFD session. Because the head doesn't receive any
BFD Control packet packets from a tail, the head of the p2mp P2MP BFD session
transmits all BFD Control packets with the value of the Your
Discriminator field set to zero. As a result, a tail cannot
demultiplex BFD sessions using Your Discriminator, as defined in
[RFC5880]. [RFC8562] requires that to To demultiplex BFD sessions, [RFC8562] requires that the
tail uses use the source IP address, My Discriminator, and the identity of
the multipoint tree from which the BFD Control packet was received.
If the BFD Control packet is encapsulated in IP/UDP, then the source
IP address MUST be used to demultiplex the received BFD Control
packet as described in Section 3.1. The non-IP encapsulation case is
described in Section 3.2.
3.1. IP Encapsulation of Multipoint BFD
[RFC8562] defines IP/UDP encapsulation for multipoint BFD over p2mp P2MP
MPLS LSP. This document updates Section 5.8 of [RFC8562] regarding
the selection of the IPv6 destination address: address as follows:
* The sender of an MPLS echo request SHOULD use an address from the
Dummy IPv6 Prefix range TBA2/64 100:0:0:1::/64 (see Section 7.1. 7.1).
* The sender of an MPLS echo request MAY select the IPv6 destination
address from the ::ffff:7f00/104 range.
The Motivation section
Section 1.2 of [RFC6790] lists several advantages of generating the
entropy value by an ingress Label Switching Router (LSR) compared to
when a transit LSR infers entropy using the information in the MPLS
label stack or payload. Thus, this This specification further clarifies that:
* if multiple alternative paths for the given p2mp P2MP LSP Forwarding
Equivalence Class (FEC) exist, the MultipointHead SHOULD use the
Entropy Label [RFC6790] used for LSP Ping [RFC8029] to exercise
those particular alternative paths;
* or the MultipointHead MAY use the UDP port number to possibly
exercise those particular alternate paths.
3.2. Non-IP Encapsulation of Multipoint BFD
In some environments, the overhead of extra IP/UDP encapsulations may
be considered burdensome, making which makes the use of more compact Generic
Associated Channel (G-ACh) ([RFC5586]) [RFC5586] encapsulation attractive. Also,
the validation of the IP/UDP encapsulation of a BFD Control packet in
a p2mp P2MP BFD session may fail because of a problem related to neither
the MPLS label stack nor to BFD. Avoiding unnecessary encapsulation of p2mp
P2MP BFD over an MPLS LSP improves the accuracy of the correlation of
the detected failure and defect in MPLS LSP.
If a BFD Control packet in PW-ACH encapsulation (without IP/UDP
Headers) is to be used in ACH, an implementation would not be able to
verify the identity of the MultipointHead and, as a result, will not
properly demultiplex BFD packets. Hence, a new channel type value is
needed.
Non-IP encapsulation for multipoint BFD over p2mp P2MP MPLS LSP (shown in
Figure 1) MUST use the G-ACh Label (GAL) (see [RFC5586]) [RFC5586] at the bottom of
the label stack followed by an Associated Channel Header (ACH). If a
BFD Control packet in PW-ACH encapsulation (without IP/UDP Headers)
is to be used in ACH, an implementation would not be able to verify
the identity of the MultipointHead and, as a result, will not
properly demultiplex BFD packets. Hence, a new channel type value is
needed. The Channel Type field in ACH MUST be set to Multipoint BFD
Session (TBA1) value (Section (0x0013) (see Section 7.2). To provide the identity of the
MultipointHead for the particular multipoint BFD session, a Source
Address TLV, as defined in Section 4.1 of [RFC7212], MUST immediately
follow a BFD Control message. The use of other TLVs is outside the
scope of this document.
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| LSP Label | TC |S| TTL |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| GAL | TC |1| TTL |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|0 0 0 1|Version| Flags | Channel Type = TBA1 0x0013 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
~ BFD Control Message ~
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type=0 | Reserved | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Reserved | Address Family |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
~ Address ~
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 1: Non-IP Encapsulation for Multipoint BFD Over over a
Multicast MPLS LSP
Fields
The fields in Figure 1 are interpreted as follows:
* the The top three four-octet words as are defined in [RFC5586]; [RFC5586].
* the The BFD Control Message field is as defined in [RFC5880]; [RFC5880].
* all All the remaining fields are as defined in Section 4.1 of [RFC7212].
4. Bootstrapping Multipoint BFD
4.1. LSP Ping
LSP Ping is the part of the on-demand OAM toolset used to detect and
localize defects in the data plane and verify the control plane
against the data plane by ensuring that the LSP is mapped to the same
FEC at both egress and ingress endpoints.
LSP Ping, as defined in [RFC6425], MAY be used to bootstrap
MultipointTail. If LSP Ping is used, it MUST include the Target FEC
TLV and the BFD Discriminator TLV defined in [RFC5884]. For the case
of p2mp P2MP MPLS LSP, the Target FEC TLV MUST use sub-TLVs defined in
Section 3.1 of [RFC6425]. For the case of p2mp P2MP SR policy with SR-MPLS an SR-
MPLS data plane, an implementation of this specification MUST follow
the procedures defined in [RFC8287]. Setting the value of the Reply
Mode field to "Do not reply" [RFC8029] for the LSP Ping to bootstrap
the MultipointTail of the p2mp P2MP BFD session is RECOMMENDED. Indeed,
because BFD over a multipoint network uses BFD Demand mode, the MPLS
echo reply from a tail has no useful information to convey to the
head, unlike in the case of the BFD over a p2p P2P MPLS LSP [RFC5884]. A
MultipointTail that receives an LSP Ping that includes the BFD
Discriminator TLV:
* MUST validate the LSP Ping;
* MUST associate the received BFD Discriminator value with the p2mp P2MP
LSP;
* MUST create a p2mp P2MP BFD session and set bfd.SessionType =
MultipointTail as described in [RFC8562]; and
* MUST use the source IP address of the LSP Ping, the value of BFD
Discriminator from the BFD Discriminator TLV, and the identity of
the p2mp P2MP LSP to properly demultiplex BFD sessions.
Besides bootstrapping a BFD session over a p2mp P2MP LSP, LSP Ping SHOULD
be used to verify the control plane against the data plane
periodically by checking that the p2mp P2MP LSP is mapped to the same FEC
at the MultipointHead and all active MultipointTails. The rate of
generation of these LSP Ping Echo request messages SHOULD be
significantly less than the rate of generation of the BFD Control
packets because LSP Ping requires more processing to validate the
consistency between the data plane and the control plane. An
implementation MAY provide configuration options to control the rate
of generation of the periodic LSP Ping Echo request messages.
4.2. Control Plane
The BFD Discriminator Attribute attribute MAY be used to bootstrap a multipoint
BFD session on a tail, following the format and procedures given in
Section 3.1.6 of [RFC9026].
5. Operation of Multipoint BFD with Active Tail over P2MP MPLS LSP
[RFC8562] defined defines how the BFD Demand mode can be used in multipoint
networks. When applied in MPLS, the procedures specified in
[RFC8562] allow an egress LSR to detect a failure of in the part of the
MPLS p2mp P2MP LSP from the ingress LSR to that egress LSR. The ingress
LSR is not aware of the state of the p2mp P2MP LSP. [RFC8563], using
mechanisms defined in [RFC8562], defined defines the behavior of an "active tail" behavior. active
tail. An active tail might notify the head of the detected failure
and responds respond to a poll sequence initiated by the head. The first
method, referred to as Head "Head Notification without Polling, Polling", is
mentioned in Section 5.2.1
[RFC8563], of [RFC8563]) and is the simplest of all the
methods described in [RFC8563]. The use of this method in BFD over
MPLS p2mp P2MP LSP is discussed in this document. Analysis of other
methods of for a head learning to learn of the state of an MPLS
p2mp P2MP LSP is
outside the scope of this document.
As specified in [RFC8563] for the active tail mode, [RFC8563], BFD variables MUST be as follows: follows for the
active tail mode:
* On an ingress LSR:
*
- bfd.SessionType is MultipointHead;
* MultipointHead.
- bfd.RequiredMinRxInterval is set to nonzero, allowing egress LSRs to
send BFD Control packets.
* On an egress LSR:
*
- bfd.SessionType is MultipointTail;
* MultipointTail.
- bfd.SilentTail is set to zero.
In
Section 5.2.1 of [RFC8563] is noted notes that "the tail sends unsolicited BFD
packets in response to the detection of a multipoint path failure"
but without the does not provide specifics on about the information in the packet
and packets
or the frequency of transmissions. This document defines below the The procedure of for an active tail
with unsolicited notifications for p2mp P2MP MPLS LSP. LSP is defined below.
Upon detecting the failure of the p2mp P2MP MPLS LSP, an egress LSR sends
a BFD Control packet with the following settings:
* the The Poll (P) bit is set; set.
* the The Status (Sta) field is set to the Down value; value.
* the The Diagnostic (Diag) field is set to the Control Detection Time
Expired
value; value.
* the The value of the Your Discriminator field is set to the value the
egress LSR has been using to demultiplex that BFD multipoint
session;
session.
* The BFD Control packet MAY be encapsulated in IP/UDP with the
destination IP address of the ingress LSR and the UDP destination
port number set to 4784 per [RFC5883]. If non-IP encapsulation is
used, then a BFD Control packet is encapsulated using PW-ACH
encapsulation (without IP/UDP Headers) with Channel Type 0x0007
[RFC5885];
[RFC5885].
* these The BFD Control packets are transmitted at the rate of one per
second until either 1) it receives a control packet valid for this
BFD session with the Final (F) bit set from the ingress LSR or 2)
the defect condition clears. However, to improve the likelihood
of notifying the ingress LSR of the failure of the p2mp P2MP MPLS LSP,
the egress LSR SHOULD initially transmit three BFD Control packets
defined above in short succession. The actual transmission of the
periodic BFD Control message MUST be jittered by up to 25% within
one-second intervals. Thus, the interval MUST be reduced by a
random value of 0 to 25%, to reduce the possibility of congestion
on the ingress LSR's data and control planes.
As described above, an ingress LSR that has received the BFD Control
packet sends the unicast IP/UDP encapsulated BFD Control packet with
the Final (F) bit set to the egress LSR. In some scenarios, e.g., scenarios (e.g.,
when a p2mp P2MP LSP is broken close to its root, root and the number of egress
LSRs is significantly large, large), the root might receive a large number
of notifications. The notifications from leaves to the root will not
use resources allocated for the monitored multicast flow and, as a
result, will not congest that particular flow, although they may
negatively affect other flows. However, the control plane of the
ingress LSR might be congested by the BFD Control packets transmitted
by egress LSRs and the process of generating unicast BFD Control
packets, as noted above. To mitigate that, a BFD implementation that
supports this specification is RECOMMENDED to use a rate limiter of
received BFD Control packets passed to the ingress LSR’s LSR's control
plane for processing.
6. Security Considerations
This document does not introduce new security considerations but
inherits all security considerations from [RFC5880], [RFC5884],
[RFC7726], [RFC8562], [RFC8029], and [RFC6425].
Also, BFD for p2mp P2MP MPLS LSP LSPs MUST follow the requirements listed in
section
Section 4.1 of [RFC4687] to avoid congestion in the control plane or
the data plane caused by the rate of generating BFD Control packets.
An operator SHOULD consider the amount of extra traffic generated by
p2mp
P2MP BFD when selecting the interval at which the MultipointHead will
transmit BFD Control packets. The operator MAY consider the size of
the packet the MultipointHead transmits periodically as using IP/UDP
encapsulation, which adds up to 28 octets, more octets (more than 50% of the BFD
Control packet length, comparing length) compared to G-ACh encapsulation.
7. IANA Considerations
7.1. IPv6 Special-Purpose Address Allocation
IANA is requested to allocate an IPv6 TBA2/64 prefix as Dummy IPv6
Prefix has allocated the following in the "IANA IPv6 Special Purpose Special-Purpose
Address Registry"
[IANA-IPv6-Special-Purpose-Address-Registry] as in Table 1.
+=======+======+=============+==========+===========+======+===========+===========+=========+=========+
|Address|Name |RFC |Allocation|Termination|Source|Destination|Forwardable|Globally |Reserved-|
|Block | | |Date |Date | | | |Reachable|by- |
| | | | | | | | | |Protocol |
+=======+======+=============+==========+===========+======+===========+===========+=========+=========+
|TBA2 |Dummy |This document|The date |N/A |True |False |False |False |False |
| |IPv6 | |of | | | | | | |
| |Prefix| |allocation| | | | | | |
+-------+------+-------------+----------+-----------+------+-----------+-----------+---------+---------+
Table 1: [IANA-IPv6-REG]:
Address Block: 100:0:0:1::/64
Name: Dummy IPv6 Address Prefix
RFC: RFC 9780
Allocation Date: 2025-04
Termination Date: N/A
Source: True
Destination: False
Forwardable: False
Globally Reachable: False
Reserved-by-Protocol: False
7.2. Multipoint BFD over MPLS LSP Generalized Associated Channel (G-ACh) Type
IANA is requested to allocate has allocated the following value (TBA1) from its MPLS in the "MPLS Generalized
Associated Channel (G-ACh) Types Types" registry.
+=======+========================+===============+
+========+========================+===========+
| Value | Description | Reference |
+=======+========================+===============+
+========+========================+===========+
| TBA1 0x0013 | Multipoint BFD Session | This document RFC 9780 |
+-------+------------------------+---------------+
+--------+------------------------+-----------+
Table 2: 1: Multipoint BFD Session G-ACh Type
8. Acknowledgements
The authors sincerely appreciate the comments received from Andrew
Malis, Italo Busi, Shraddha Hegde, and thought stimulating questions
from Carlos Pignataro.
9. References
9.1.
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>.
[RFC5586] Bocci, M., Ed., Vigoureux, M., Ed., and S. Bryant, Ed.,
"MPLS Generic Associated Channel", RFC 5586,
DOI 10.17487/RFC5586, June 2009,
<https://www.rfc-editor.org/info/rfc5586>.
[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>.
[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>.
[RFC5885] Nadeau, T., Ed. and C. Pignataro, Ed., "Bidirectional
Forwarding Detection (BFD) for the Pseudowire Virtual
Circuit Connectivity Verification (VCCV)", RFC 5885,
DOI 10.17487/RFC5885, June 2010,
<https://www.rfc-editor.org/info/rfc5885>.
[RFC6425] Saxena, S., Ed., Swallow, G., Ali, Z., Farrel, A.,
Yasukawa, S., and T. Nadeau, "Detecting Data-Plane
Failures in Point-to-Multipoint MPLS - Extensions to LSP
Ping", RFC 6425, DOI 10.17487/RFC6425, November 2011,
<https://www.rfc-editor.org/info/rfc6425>.
[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>.
[RFC7212] Frost, D., Bryant, S., and M. Bocci, "MPLS Generic
Associated Channel (G-ACh) Advertisement Protocol",
RFC 7212, DOI 10.17487/RFC7212, June 2014,
<https://www.rfc-editor.org/info/rfc7212>.
[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>.
[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>.
[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>.
[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>.
9.2.
8.2. Informative References
[IANA-IPv6-Special-Purpose-Address-Registry]
[IANA-IPv6-REG]
IANA, "IANA IPv6 Special-Purpose Address Registry",
<https://www.iana.org/assignments/iana-ipv6-special-
registry/iana-ipv6-special-registry.xhtml>.
registry>.
[RFC4291] Hinden, R. and S. Deering, "IP Version 6 Addressing
Architecture", RFC 4291, DOI 10.17487/RFC4291, February
2006, <https://www.rfc-editor.org/info/rfc4291>.
[RFC4687] Yasukawa, S., Farrel, A., King, D., and T. Nadeau,
"Operations and Management (OAM) Requirements for Point-
to-Multipoint MPLS Networks", RFC 4687,
DOI 10.17487/RFC4687, September 2006,
<https://www.rfc-editor.org/info/rfc4687>.
Acknowledgements
The authors sincerely appreciate the comments received from Andrew
Malis, Italo Busi, and Shraddha Hegde. The authors also appreciate
the thought-stimulating questions from Carlos Pignataro.
Authors' Addresses
Greg Mirsky
Ericsson
Email: gregimirsky@gmail.com
Gyan Mishra
Verizon Inc.
Email: gyan.s.mishra@verizon.com
Donald Eastlake, Eastlake 3rd
Independent
2386 Panoramic Circle
Apopka, FL 32703
United States of America
Email: d3e3e3@gmail.com