draft-ietf-bfd-multipoint-11.txt   draft-ietf-bfd-multipoint-12.txt 
Internet Engineering Task Force D. Katz Internet Engineering Task Force D. Katz
Internet-Draft Juniper Networks Internet-Draft Juniper Networks
Intended status: Standards Track D. Ward Intended status: Standards Track D. Ward
Expires: June 14, 2018 Cisco Systems Expires: June 22, 2018 Cisco Systems
S. Pallagatti, Ed. S. Pallagatti, Ed.
Individual contributor Individual contributor
December 11, 2017 G. Mirsky, Ed.
ZTE Corp.
December 19, 2017
BFD for Multipoint Networks BFD for Multipoint Networks
draft-ietf-bfd-multipoint-11 draft-ietf-bfd-multipoint-12
Abstract Abstract
This document describes extensions to the Bidirectional Forwarding This document describes extensions to the Bidirectional Forwarding
Detection (BFD) protocol for its use in multipoint and multicast Detection (BFD) protocol for its use in multipoint and multicast
networks. Comments on this draft should be directed to rtg- networks. Comments on this draft should be directed to rtg-
bfd@ietf.org. bfd@ietf.org.
Requirements Language Requirements Language
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
document are to be interpreted as described in RFC 2119 [RFC2119]. "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.
Status of This Memo Status of This Memo
This Internet-Draft is submitted in full conformance with the This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79. provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet- working documents as Internet-Drafts. The list of current Internet-
Drafts is at https://datatracker.ietf.org/drafts/current/. Drafts is at https://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress." material or to cite them other than as "work in progress."
This Internet-Draft will expire on June 14, 2018. This Internet-Draft will expire on June 22, 2018.
Copyright Notice Copyright Notice
Copyright (c) 2017 IETF Trust and the persons identified as the Copyright (c) 2017 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 Provisions Relating to IETF Documents
(https://trustee.ietf.org/license-info) in effect on the date of (https://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents publication of this document. Please review these documents
skipping to change at page 2, line 22 skipping to change at page 2, line 27
the Trust Legal Provisions and are provided without warranty as the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License. described in the Simplified BSD License.
Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Goals . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 2. Goals . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
3. Overview . . . . . . . . . . . . . . . . . . . . . . . . . . 4 3. Overview . . . . . . . . . . . . . . . . . . . . . . . . . . 4
4. Protocol Details . . . . . . . . . . . . . . . . . . . . . . 4 4. Protocol Details . . . . . . . . . . . . . . . . . . . . . . 4
4.1. Multipoint BFD Control Packets . . . . . . . . . . . . . 4 4.1. Multipoint BFD Control Packets . . . . . . . . . . . . . 4
4.2. Session Model . . . . . . . . . . . . . . . . . . . . . . 4 4.2. Session Model . . . . . . . . . . . . . . . . . . . . . . 5
4.3. Session Failure Semantics . . . . . . . . . . . . . . . . 5 4.3. Session Failure Semantics . . . . . . . . . . . . . . . . 5
4.4. State Variables . . . . . . . . . . . . . . . . . . . . . 5 4.4. State Variables . . . . . . . . . . . . . . . . . . . . . 5
4.4.1. New State Variables . . . . . . . . . . . . . . . . . 5 4.4.1. New State Variables . . . . . . . . . . . . . . . . . 5
4.4.2. State Variable Initialization and Maintenance . . . . 6 4.4.2. State Variable Initialization and Maintenance . . . . 6
4.5. State Machine . . . . . . . . . . . . . . . . . . . . . . 6 4.5. State Machine . . . . . . . . . . . . . . . . . . . . . . 6
4.6. Session Establishment . . . . . . . . . . . . . . . . . . 7 4.6. Session Establishment . . . . . . . . . . . . . . . . . . 7
4.7. Discriminators and Packet Demultiplexing . . . . . . . . 7 4.7. Discriminators and Packet Demultiplexing . . . . . . . . 7
4.8. Packet consumption on tails . . . . . . . . . . . . . . . 8 4.8. Packet consumption on tails . . . . . . . . . . . . . . . 8
4.9. Bringing Up and Shutting Down Multipoint BFD Service . . 8 4.9. Bringing Up and Shutting Down Multipoint BFD Service . . 8
4.10. Timer Manipulation . . . . . . . . . . . . . . . . . . . 8 4.10. Timer Manipulation . . . . . . . . . . . . . . . . . . . 9
4.11. Detection Times . . . . . . . . . . . . . . . . . . . . . 9 4.11. Detection Times . . . . . . . . . . . . . . . . . . . . . 9
4.12. State Maintenance for Down/AdminDown Sessions . . . . . . 9 4.12. State Maintenance for Down/AdminDown Sessions . . . . . . 9
4.12.1. MultipointHead Sessions . . . . . . . . . . . . . . 9 4.12.1. MultipointHead Sessions . . . . . . . . . . . . . . 10
4.12.2. MultipointTail Sessions . . . . . . . . . . . . . . 9 4.12.2. MultipointTail Sessions . . . . . . . . . . . . . . 10
4.13. Base Specification Text Replacement . . . . . . . . . . . 10 4.13. Base Specification Text Replacement . . . . . . . . . . . 10
4.13.1. Reception of BFD Control Packets . . . . . . . . . . 10 4.13.1. Reception of BFD Control Packets . . . . . . . . . . 10
4.13.2. Demultiplexing BFD Control Packets . . . . . . . . . 12 4.13.2. Demultiplexing BFD Control Packets . . . . . . . . . 13
4.13.3. Transmitting BFD Control Packets . . . . . . . . . . 13 4.13.3. Transmitting BFD Control Packets . . . . . . . . . . 14
5. Assumptions . . . . . . . . . . . . . . . . . . . . . . . . . 16 5. Assumptions . . . . . . . . . . . . . . . . . . . . . . . . . 16
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 16 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 16
7. Security Considerations . . . . . . . . . . . . . . . . . . . 16 7. Security Considerations . . . . . . . . . . . . . . . . . . . 17
8. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 17 8. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 17
9. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 17 9. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 17
10. Normative References . . . . . . . . . . . . . . . . . . . . 17 10. Normative References . . . . . . . . . . . . . . . . . . . . 17
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 17 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 18
1. Introduction 1. Introduction
The Bidirectional Forwarding Detection protocol [RFC5880] specifies a The Bidirectional Forwarding Detection protocol [RFC5880] specifies a
method for verifying unicast connectivity between a pair of systems. method for verifying unicast connectivity between a pair of systems.
This document defines a method for using BFD to provide verification This document defines a method for using BFD to provide verification
of multipoint or multicast connectivity between a multipoint sender of multipoint or multicast connectivity between a multipoint sender
(the "head") and a set of one or more multipoint receivers (the (the "head") and a set of one or more multipoint receivers (the
"tails"). "tails").
As multipoint transmissions are inherently unidirectional, this As multipoint transmissions are inherently unidirectional, this
mechanism purports only to verify this unidirectional connectivity. mechanism purports only to verify this unidirectional connectivity.
Although this seems in conflict with the "Bidirectional" in BFD, it Although this seems in conflict with the "Bidirectional" in BFD, the
is a natural fit for that protocol. protocol is capable supporting this use case.
This application of BFD allows for the tails to detect a lack of This application of BFD allows for the tails to detect a lack of
connectivity from the head. Due to unidirectional nature, virtually connectivity from the head. Due to unidirectional nature, virtually
all options and timing parameters are controlled by the head. all options and timing parameters are controlled by the head.
As an option, the tail may notify the head of the lack of multipoint As an option, the tail may notify the head of the lack of multipoint
connectivity. Details of tail notification to head are outside the connectivity. Details of tail notification to head are outside the
scope of this document. scope of this document.
Throughout this document, the term "multipoint" is defined as a Throughout this document, the term "multipoint" is defined as a
mechanism by which one or more systems receive packets sent by a mechanism by which one or more systems receive packets sent by a
single sender. This specifically includes such things as IP single sender. This specifically includes such things as IP
multicast and point-to-multipoint MPLS. multicast and point-to-multipoint MPLS.
Term "connectivity" in this document is not being used in context of
connectivity verification in transport network but as an alternative
to "continuity", i.e. existence of a path between the sender and the
receiver.
This document effectively modifies and adds to the base BFD This document effectively modifies and adds to the base BFD
specification. It is the intention of the authors to fold these specification. It is the intention of the authors to fold these
extensions into the base specification at the appropriate time. extensions into the base specification at the appropriate time.
2. Goals 2. Goals
The primary goal of this mechanism is to allow tails to rapidly The primary goal of this mechanism is to allow tails to rapidly
detect the fact that multipoint connectivity from the head has detect the fact that multipoint connectivity from the head has
failed. failed.
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A further goal is to support multiple, overlapping multipoint paths, A further goal is to support multiple, overlapping multipoint paths,
as well as multipoint paths with multiple heads, and to allow point- as well as multipoint paths with multiple heads, and to allow point-
to-point BFD sessions to operate simultaneously among the systems to-point BFD sessions to operate simultaneously among the systems
participating in Multipoint BFD. participating in Multipoint BFD.
A final goal is to integrate multipoint operation into the base A final goal is to integrate multipoint operation into the base
specification in such a way as to make it relatively easy to support specification in such a way as to make it relatively easy to support
both multipoint and point-to-point operation in a single both multipoint and point-to-point operation in a single
implementation. implementation.
It is a non-goal for this protocol to verify point-to-point It is a non-goal for this protocol to verify point-to-point bi-
connectivity between the head and any tails. This can be done directional connectivity between the head and any tails. This can be
independently (and with no penalty in protocol overhead) by using done independently (and with no penalty in protocol overhead) by
point-to-point BFD. using point-to-point BFD.
3. Overview 3. Overview
The heart of this protocol is the periodic transmission of BFD The heart of this protocol is the periodic transmission of BFD
Control packets along a multipoint path, from the head to all tails Control packets along a multipoint path, from the head to all tails
on the tree. The contents of the BFD packets provide the means for on the tree. The contents of the BFD packets provide the means for
the tails to calculate the detection time for path failure. If no the tails to calculate the detection time for path failure. If no
BFD Control packets are received by a tail for a detection time, the BFD Control packets are received by a tail for a detection time, the
tail declares the path to have failed. For some applications this is tail declares the path to have failed. For some applications this is
the only mechanism necessary; the head can remain ignorant of the the only mechanism necessary; the head can remain ignorant of the
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the M bit. This means that Multipoint BFD does not depend on the the M bit. This means that Multipoint BFD does not depend on the
recipient of a packet to know whether the packet was received over a recipient of a packet to know whether the packet was received over a
multipoint path. This can be useful in scenarios where this multipoint path. This can be useful in scenarios where this
information may not be available to the recipient. information may not be available to the recipient.
4.2. Session Model 4.2. Session Model
Multipoint BFD is modeled as a set of sessions of different types. Multipoint BFD is modeled as a set of sessions of different types.
The elements of procedure differ slightly for each type. The elements of procedure differ slightly for each type.
Point-to-point sessions, as described in [BFD], are of type Point-to-point sessions, as described in [RFC5880], are of type
PointToPoint. PointToPoint.
The head has a session of type MultipointHead that is bound to a The head has a session of type MultipointHead that is bound to a
multipoint path. Multipoint BFD Control packets are sent by this multipoint path. Multipoint BFD Control packets are sent by this
session over the multipoint path, and no BFD Control packets are session over the multipoint path, and no BFD Control packets are
received by it. received by it.
Each tail has a session of type MultipointTail associated with a Each tail has a session of type MultipointTail associated with a
multipoint path. These sessions receive BFD Control packets from the multipoint path. These sessions receive BFD Control packets from the
head over multipoint path. head over multipoint path.
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has lost contact with the head (or the head has been administratively has lost contact with the head (or the head has been administratively
disabled) and the tail should take appropriate action. disabled) and the tail should take appropriate action.
4.4. State Variables 4.4. State Variables
Multipoint BFD introduces some new state variables, and modifies the Multipoint BFD introduces some new state variables, and modifies the
usage of a few existing ones. usage of a few existing ones.
4.4.1. New State Variables 4.4.1. New State Variables
A number of state variables are added to the base specification in A number of state variables and their values are added to the base
support of Multipoint BFD. BFD [RFC5880] and base S-BFD [RFC7880] specifications in support of
Multipoint BFD.
bfd.SessionType bfd.SessionType
The type of this session. Allowable values are: The type of this session as defined in [RFC7880]. Newly added
values are:
PointToPoint: Classic point-to-point BFD. PointToPoint: Classic point-to-point BFD.
MultipointHead: A session on the head responsible for the MultipointHead: A session on the head responsible for the
periodic transmission of multipoint BFD Control packets periodic transmission of multipoint BFD Control packets
along the multipoint path. along the multipoint path.
MultipointTail: A multipoint session on a tail. MultipointTail: A multipoint session on a tail.
This variable MUST be initialized to the appropriate type when This variable MUST be initialized to the appropriate type when
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and with Your Discr set to zero. and with Your Discr set to zero.
IP and MPLS multipoint tails MUST demultiplex BFD packets based on a IP and MPLS multipoint tails MUST demultiplex BFD packets based on a
combination of the source address, My Discriminator and the identity combination of the source address, My Discriminator and the identity
of the multipoint tree which the Multipoint BFD Control packet was of the multipoint tree which the Multipoint BFD Control packet was
received from. Together they uniquely identify the head of the received from. Together they uniquely identify the head of the
multipoint path. Bootstrapping BFD session to a multipoint LSP in multipoint path. Bootstrapping BFD session to a multipoint LSP in
case of penultimate hop popping is outside the scope of this case of penultimate hop popping is outside the scope of this
document. document.
Note that, unlike PointToPoint sessions, the discriminator values on Note that, unlike PointToPoint sessions, the My Discriminator value
all multipoint session types MUST NOT be changed during the life of a on MultipointHead session MUST NOT be changed during the life of a
session. This is a side effect of the more complex demultiplexing session. This is a side effect of the more complex demultiplexing
scheme. scheme.
4.8. Packet consumption on tails 4.8. Packet consumption on tails
BFD packets received on tails for a multicast group MUST be consumed BFD packets received on tails for a multicast group MUST be consumed
by tails and MUST not be forwarded to receivers. Session of type by tails and MUST NOT be forwarded to receivers. Session of type
MultipointTail MUST identify the packet as BFD with the help of MultipointTail MUST identify the packet as BFD with the help of
destination UDP port number "3784" on IP multipoint path. For destination UDP port number "3784" on IP multipoint path.
multipoint LSP, MultipointTail MUST use destination UDP port "3784"
and IP "127.0.0.0/8" range. Packet identified as BFD packet MUST be For multipoint LSP, when IP/UDP encapsulation of BFD control packet
consumed by MultipointTail and demultiplex as described in used, MultipointTail MUST use destination UDP port "3784" and
Section 4.13.2 "127.0.0.0/8" range for IPv4 or "0:0:0:0:0:FFFF:7F00:0/104" range for
IPv6. Packet identified as BFD packet MUST be consumed by
MultipointTail and demultiplex as described in Section 4.13.2. Use
of other types of encapsulation for multipoint LSP is outside the
scope of this document.
4.9. Bringing Up and Shutting Down Multipoint BFD Service 4.9. Bringing Up and Shutting Down Multipoint BFD Service
Because there is no three-way handshake in Multipoint BFD, a newly Because there is no three-way handshake in Multipoint BFD, a newly
started head (that does not have any previous state information started head (that does not have any previous state information
available) SHOULD start with bfd.SessionState set to Down and with available) SHOULD start with bfd.SessionState set to Down and with
bfd.RequiredMinRxInterval set to zero in the MultipointHead session. bfd.RequiredMinRxInterval set to zero in the MultipointHead session.
The session SHOULD remain in this state for a time equal to The session SHOULD remain in this state for a time equal to
(bfd.DesiredMinTxInterval * bfd.DetectMult). This will ensure that (bfd.DesiredMinTxInterval * bfd.DetectMult). This will ensure that
all MultipointTail sessions are reset (so long as the restarted head all MultipointTail sessions are reset (so long as the restarted head
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4.10. Timer Manipulation 4.10. Timer Manipulation
Because of the one-to-many mapping, a session of type MultipointHead Because of the one-to-many mapping, a session of type MultipointHead
SHOULD NOT initiate a Poll Sequence in conjunction with timer value SHOULD NOT initiate a Poll Sequence in conjunction with timer value
changes. However to indicate change in packet MultipointHead session changes. However to indicate change in packet MultipointHead session
MUST send packet with P bit set. MultipointTail session MUST NOT MUST send packet with P bit set. MultipointTail session MUST NOT
reply if packet has M, P bit set and bfd.RequiredMinRxInterval set to reply if packet has M, P bit set and bfd.RequiredMinRxInterval set to
0. 0.
The MultipointHead MUST send bfd.DetectMult packets with P bit set at The MultipointHead, when changing the transmit interval to higher
the old transmit interval before using the higher value in order to value, MUST send BFD control packets with P bit set at the old
avoid false detection timeouts at the tails. MultipointHead May also transmit interval before using the higher value in order to avoid
wait some amount of time before making the changes to the transmit false detection timeouts at the tails. MultipointHead MAY also wait
some amount of time before making the changes to the transmit
interval (through configuration). interval (through configuration).
Change in the value of bfd.RequiredMinRxInterval is outside the scope Change in the value of bfd.RequiredMinRxInterval is outside the scope
of this document. of this document.
4.11. Detection Times 4.11. Detection Times
Multipoint BFD is inherently asymmetric. As such, each session type Multipoint BFD is inherently asymmetric. As such, each session type
has a different approach to detection times. has a different approach to detection times.
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combination of other fields, possibly including source combination of other fields, possibly including source
addressing information, the My Discriminator field, and the addressing information, the My Discriminator field, and the
interface over which the packet was received. The exact interface over which the packet was received. The exact
method of selection is application-specific and is thus method of selection is application-specific and is thus
outside the scope of this specification. outside the scope of this specification.
If a matching session is found, and bfd.SessionType is not If a matching session is found, and bfd.SessionType is not
PointToPoint, the packet MUST be discarded. PointToPoint, the packet MUST be discarded.
If a matching session is not found, a new session of type If a matching session is not found, a new session of type
PointToPoint may be created, or the packet may be discarded. PointToPoint MAY be created, or the packet MAY be discarded.
This choice is outside the scope of this specification. This choice is outside the scope of this specification.
If the State field is Init and bfd.SessionType is not If the State field is Init and bfd.SessionType is not
PointToPoint, the packet MUST be discarded. PointToPoint, the packet MUST be discarded.
4.13.3. Transmitting BFD Control Packets 4.13.3. Transmitting BFD Control Packets
The following procedure replaces section 6.8.7 of [RFC5880]. The following procedure replaces section 6.8.7 of [RFC5880].
BFD Control packets MUST be transmitted periodically at the rate BFD Control packets MUST be transmitted periodically at the rate
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A system MUST NOT periodically transmit BFD Control packets if A system MUST NOT periodically transmit BFD Control packets if
bfd.RemoteMinRxInterval is zero. bfd.RemoteMinRxInterval is zero.
If bfd.SessionType is MultipointHead, the transmit interval MUST be If bfd.SessionType is MultipointHead, the transmit interval MUST be
set to bfd.DesiredMinTxInterval (this should happen automatically, as set to bfd.DesiredMinTxInterval (this should happen automatically, as
bfd.RemoteMinRxInterval will be zero.) bfd.RemoteMinRxInterval will be zero.)
If bfd.SessionType is not MultipointHead, the transmit interval MUST If bfd.SessionType is not MultipointHead, the transmit interval MUST
be recalculated whenever bfd.DesiredMinTxInterval changes, or be recalculated whenever bfd.DesiredMinTxInterval changes, or
whenever bfd.RemoteMinRxInterval changes, and is equal to the greater whenever bfd.RemoteMinRxInterval changes, and is equal to the greater
of those two values. See [BFD] sections 6.8.2 and 6.8.3 for details of those two values. See [RFC5880] sections 6.8.2 and 6.8.3 for
on transmit timers. details on transmit timers.
A system MUST NOT set the Demand (D) bit if bfd.SessionType is A system MUST NOT set the Demand (D) bit if bfd.SessionType is
MultipointTail. MultipointTail.
A system MUST NOT set the Demand (D) bit if bfd.SessionType A system MUST NOT set the Demand (D) bit if bfd.SessionType
PointToPoint unless bfd.DemandMode is 1, bfd.SessionState is Up, and PointToPoint unless bfd.DemandMode is 1, bfd.SessionState is Up, and
bfd.RemoteSessionState is Up. bfd.RemoteSessionState is Up.
If bfd.SessionType is PointToPoint or MultipointHead, a BFD Control If bfd.SessionType is PointToPoint or MultipointHead, a BFD Control
packet SHOULD be transmitted during the interval between periodic packet SHOULD be transmitted during the interval between periodic
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If authentication is in use, all tails must be configured to have a If authentication is in use, all tails must be configured to have a
common authentication key in order to receive the multipoint BFD common authentication key in order to receive the multipoint BFD
Control packets. Control packets.
6. IANA Considerations 6. IANA Considerations
This document has no actions for IANA. This document has no actions for IANA.
7. Security Considerations 7. Security Considerations
Implementations that creates MultpointTail sessions dynamically upon Implementations that create MultpointTail sessions dynamically upon
receipt of Multipoint BFD Control packets MUST implement protective receipt of Multipoint BFD Control packets MUST implement protective
measures to prevent infinite number of MultipointTail session being measures to prevent infinite number of MultipointTail sessions being
created. Below lists some points to be considered in such created. Below are listed some points to be considered in such
implementations. implementations.
If a Multipoint BFD Control packet did not arrive on a multicast If a Multipoint BFD Control packet did not arrive on a multicast
tree (ex: on expected interface, with expected MPLS label, etc), tree (ex: on expected interface, with expected MPLS label, etc),
then a MultipointTail session should not be created. then a MultipointTail session should not be created.
If redundant streams are expected for a given multicast stream, If redundant streams are expected for a given multicast stream,
then the implementations should not create more MultipointTail then the implementations should not create more MultipointTail
sessions than the number of streams. Additionally, when the sessions than the number of streams. Additionally, when the
number of MultipointTail sessions exceeds the number of expected number of MultipointTail sessions exceeds the number of expected
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[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>.
[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>.
[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>.
Authors' Addresses Authors' Addresses
Dave Katz Dave Katz
Juniper Networks Juniper Networks
1194 N. Mathilda Ave. 1194 N. Mathilda Ave.
Sunnyvale, California 94089-1206 Sunnyvale, California 94089-1206
USA USA
Email: dkatz@juniper.net Email: dkatz@juniper.net
skipping to change at page 18, line 4 skipping to change at page 18, line 31
Email: dkatz@juniper.net Email: dkatz@juniper.net
Dave Ward Dave Ward
Cisco Systems Cisco Systems
170 West Tasman Dr. 170 West Tasman Dr.
San Jose, California 95134 San Jose, California 95134
USA USA
Email: wardd@cisco.com Email: wardd@cisco.com
Santosh Pallagatti (editor) Santosh Pallagatti (editor)
Individual contributor Individual contributor
Email: santosh.pallagatti@gmail.com Email: santosh.pallagatti@gmail.com
Greg Mirsky (editor)
ZTE Corp.
Email: gregimirsky@gmail.com
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