draft-ietf-bfd-seamless-base-02.txt   draft-ietf-bfd-seamless-base-03.txt 
Internet Engineering Task Force N. Akiya Internet Engineering Task Force N. Akiya
Internet-Draft C. Pignataro Internet-Draft C. Pignataro
Updates: 5880 (if approved) D. Ward Updates: 5880 (if approved) D. Ward
Intended status: Standards Track Cisco Systems Intended status: Standards Track Cisco Systems
Expires: February 2, 2015 M. Bhatia Expires: February 24, 2015 M. Bhatia
Ionos Networks Ionos Networks
P. K. Santosh S. Pallagatti
Juniper Networks Juniper Networks
August 1, 2014 August 23, 2014
Seamless Bidirectional Forwarding Detection (S-BFD) Seamless Bidirectional Forwarding Detection (S-BFD)
draft-ietf-bfd-seamless-base-02 draft-ietf-bfd-seamless-base-03
Abstract Abstract
This document defines a simplified mechanism to use Bidirectional This document defines a simplified mechanism to use Bidirectional
Forwarding Detection (BFD) with large portions of negotiation aspects Forwarding Detection (BFD) with large portions of negotiation aspects
eliminated, thus providing benefits such as quick provisioning as eliminated, thus providing benefits such as quick provisioning as
well as improved control and flexibility to network nodes initiating well as improved control and flexibility to network nodes initiating
the path monitoring. the path monitoring.
This document updates RFC5880. This document updates RFC5880.
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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 http://datatracker.ietf.org/drafts/current/. Drafts is at http://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 February 2, 2015. This Internet-Draft will expire on February 24, 2015.
Copyright Notice Copyright Notice
Copyright (c) 2014 IETF Trust and the persons identified as the Copyright (c) 2014 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
(http://trustee.ietf.org/license-info) in effect on the date of (http://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
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include Simplified BSD License text as described in Section 4.e of include Simplified BSD License text as described in Section 4.e of
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. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3
3. Seamless BFD Overview . . . . . . . . . . . . . . . . . . . . 4 3. Seamless BFD Overview . . . . . . . . . . . . . . . . . . . . 4
4. S-BFD Discriminators . . . . . . . . . . . . . . . . . . . . 5 4. S-BFD Discriminators . . . . . . . . . . . . . . . . . . . . 5
4.1. Discriminator Pools . . . . . . . . . . . . . . . . . . . 5 4.1. S-BFD Discriminator Uniqueness . . . . . . . . . . . . . 5
4.2. S-BFD Discriminator Uniqueness . . . . . . . . . . . . . 6 4.2. Discriminator Pools . . . . . . . . . . . . . . . . . . . 6
5. Reflector BFD Session . . . . . . . . . . . . . . . . . . . . 7 5. Reflector BFD Session . . . . . . . . . . . . . . . . . . . . 7
6. State Variables . . . . . . . . . . . . . . . . . . . . . . . 7 6. State Variables . . . . . . . . . . . . . . . . . . . . . . . 7
6.1. New State Variables . . . . . . . . . . . . . . . . . . . 7 6.1. New State Variables . . . . . . . . . . . . . . . . . . . 7
6.2. State Variable Initialization and Maintenance . . . . . . 8 6.2. State Variable Initialization and Maintenance . . . . . . 8
7. S-BFD Procedures . . . . . . . . . . . . . . . . . . . . . . 8 7. S-BFD Procedures . . . . . . . . . . . . . . . . . . . . . . 8
7.1. S-BFD Packet Demultiplexing . . . . . . . . . . . . . . . 8 7.1. S-BFD Control Packet Demultiplexing . . . . . . . . . . . 8
7.2. Initiator Procedures . . . . . . . . . . . . . . . . . . 8 7.2. Initiator Procedures . . . . . . . . . . . . . . . . . . 8
7.2.1. SBFDInitiator State Machine . . . . . . . . . . . . . 9 7.2.1. SBFDInitiator State Machine . . . . . . . . . . . . . 9
7.2.2. Details of S-BFD Packet Sent by SBFDInitiator . . . . 10 7.2.2. Details of S-BFD Control Packet Sent by SBFDInitiator 10
7.3. Responder Procedures . . . . . . . . . . . . . . . . . . 10 7.3. Responder Procedures . . . . . . . . . . . . . . . . . . 10
7.3.1. Responder Demultiplexing . . . . . . . . . . . . . . 10 7.3.1. Responder Demultiplexing . . . . . . . . . . . . . . 11
7.3.2. Details of S-BFD Packet Sent by SBFDReflector . . . . 11 7.3.2. Details of S-BFD Control Packet Sent by SBFDReflector 11
7.4. Diagnostic Values . . . . . . . . . . . . . . . . . . . . 11 7.4. Diagnostic Values . . . . . . . . . . . . . . . . . . . . 11
7.5. The Poll Sequence . . . . . . . . . . . . . . . . . . . . 11 7.5. The Poll Sequence . . . . . . . . . . . . . . . . . . . . 11
7.6. Control Plane Independent (C) . . . . . . . . . . . . . . 11 7.6. Control Plane Independent (C) . . . . . . . . . . . . . . 12
7.7. Additional SBFDInitiator Behaviors . . . . . . . . . . . 12 7.7. Additional SBFDInitiator Behaviors . . . . . . . . . . . 12
7.8. Additional SBFDReflector Behaviors . . . . . . . . . . . 12 7.8. Additional SBFDReflector Behaviors . . . . . . . . . . . 12
8. Scaling Aspect . . . . . . . . . . . . . . . . . . . . . . . 13 8. Scaling Aspect . . . . . . . . . . . . . . . . . . . . . . . 13
9. Co-existence with Classical BFD Sessions . . . . . . . . . . 13 9. Co-existence with Classical BFD Sessions . . . . . . . . . . 13
10. S-BFD Echo Function . . . . . . . . . . . . . . . . . . . . . 13 10. S-BFD Echo Function . . . . . . . . . . . . . . . . . . . . . 13
11. Security Considerations . . . . . . . . . . . . . . . . . . . 14 11. Security Considerations . . . . . . . . . . . . . . . . . . . 14
12. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 15 12. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 15
13. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 15 13. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 15
14. Contributing Authors . . . . . . . . . . . . . . . . . . . . 15 14. Contributing Authors . . . . . . . . . . . . . . . . . . . . 15
15. References . . . . . . . . . . . . . . . . . . . . . . . . . 16 15. References . . . . . . . . . . . . . . . . . . . . . . . . . 16
15.1. Normative References . . . . . . . . . . . . . . . . . . 16 15.1. Normative References . . . . . . . . . . . . . . . . . . 16
15.2. Informative References . . . . . . . . . . . . . . . . . 16 15.2. Informative References . . . . . . . . . . . . . . . . . 16
Appendix A. Loop Problem . . . . . . . . . . . . . . . . . . . . 16 Appendix A. Loop Problem . . . . . . . . . . . . . . . . . . . . 17
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 18 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 18
1. Introduction 1. Introduction
Bidirectional Forwarding Detection (BFD), [RFC5880] and related Bidirectional Forwarding Detection (BFD), [RFC5880] and related
documents, has efficiently generalized the failure detection documents, has efficiently generalized the failure detection
mechanism for multiple protocols and applications. There are some mechanism for multiple protocols and applications. There are some
improvements which can be made to better fit existing technologies. improvements which can be made to better fit existing technologies.
There is a possibility of evolving BFD to better fit new There is a possibility of evolving BFD to better fit new
technologies. This document focuses on several aspects of BFD in technologies. This document focuses on several aspects of BFD in
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2. Terminology 2. Terminology
The reader is expected to be familiar with the BFD, IP and MPLS The reader is expected to be familiar with the BFD, IP and MPLS
terminologies and protocol constructs. This section describes terminologies and protocol constructs. This section describes
several new terminologies introduced by S-BFD. several new terminologies introduced by S-BFD.
o Classical BFD - BFD session types based on [RFC5880]. o Classical BFD - BFD session types based on [RFC5880].
o S-BFD - Seamless BFD. o S-BFD - Seamless BFD.
o S-BFD packet - a BFD control packet destined to or sourced from o S-BFD control packet - a BFD control packet for the S-BFD
the well-known S-BFD port. mechanism.
o S-BFD echo packet - a BFD echo packet for the S-BFD mechanism.
o S-BFD packet - a BFD control packet or a BFD echo packet.
o Entity - a function on a network node that S-BFD mechanism allows o Entity - a function on a network node that S-BFD mechanism allows
remote network nodes to perform continuity test to. An entity can remote network nodes to perform continuity test to. An entity can
be abstract (ex: reachability) or specific (ex: IP addresses, be abstract (ex: reachability) or specific (ex: IP addresses,
router-IDs, functions). router-IDs, functions).
o SBFDInitiator - an S-BFD session on a network node that performs a o SBFDInitiator - an S-BFD session on a network node that performs a
continuity test to a remote entity by sending S-BFD packets. continuity test to a remote entity by sending S-BFD packets.
o SBFDReflector - an S-BFD session on a network node that listens o SBFDReflector - an S-BFD session on a network node that listens
for incoming S-BFD packets to local entities and generates for incoming S-BFD control packets to local entities and generates
response S-BFD packets. response S-BFD control packets.
o Reflector BFD session - synonymous with SBFDReflector. o Reflector BFD session - synonymous with SBFDReflector.
o S-BFD discriminator - a BFD discriminator allocated for a local o S-BFD discriminator - a BFD discriminator allocated for a local
entity and is being listened by an SBFDReflector. entity and is being listened by an SBFDReflector.
o BFD discriminator - a BFD discriminator allocated for an o BFD discriminator - a BFD discriminator allocated for an
SBFDInitiator. SBFDInitiator.
o Initiator - a network node hosting an SBFDInitiator. o Initiator - a network node hosting an SBFDInitiator.
o Responder - a network node hosting an SBFDReflector. o Responder - a network node hosting an SBFDReflector.
Below figure describes the relationship between S-BFD terminologies. Below figure describes the relationship between S-BFD terminologies.
+---------------------+ +---------------------+ +---------------------+ +------------------------+
| Initiator | | Responder | | Initiator | | Responder |
| +-----------------+ | | +-----------------+ | | +-----------------+ | | +-----------------+ |
| | SBFDInitiator |--- S-BFD packet -->| SBFDReflector | | | | SBFDInitiator |---S-BFD ctrl pkt----->| SBFDReflector | |
| | +-------------+ | | | | +-------------+ | | | | +-------------+ |<--S-BFD ctrl pkt------| +-------------+ | |
| | | BFD discrim | | | | | |S-BFD discrim| | | | | | BFD discrim | | | | | |S-BFD discrim| | |
| | +-------------+ |<-- S-BFD packet ---| +----------^--+ | | | | | | |---S-BFD echo pkt---+ | | | | |
| +-----------------+ | | +------------|----+ | | | +-------------+ | | | | | +----------^--+ | |
| | | | | | +-----------------+<-------------------+ +------------|----+ |
| | | +---v----+ | | | | | |
| | | | Entity | | | | | +---v----+ |
| | | +--------+ | | | | | Entity | |
+---------------------+ +---------------------+ | | | +--------+ |
+---------------------+ +------------------------+
Figure 1: S-BFD Terminology Relationship Figure 1: S-BFD Terminology Relationship
3. Seamless BFD Overview 3. Seamless BFD Overview
An S-BFD module on each network node allocates one or more S-BFD An S-BFD module on each network node allocates one or more S-BFD
discriminators for local entities, and creates a reflector BFD discriminators for local entities, and creates a reflector BFD
session. Allocated S-BFD discriminators may be advertised by session. Allocated S-BFD discriminators may be advertised by
applications (ex: OSPF/IS-IS). Required result is that applications, applications (ex: OSPF/IS-IS). Required result is that applications,
on other network nodes, possess the knowledge of the mapping from on other network nodes, possess the knowledge of the mapping from
remote entities to S-BFD discriminators. The reflector BFD session remote entities to S-BFD discriminators. The reflector BFD session
is to, upon receiving an S-BFD packet targeted to one of local S-BFD is to, upon receiving an S-BFD control packet targeted to one of
discriminator values, transmit a response S-BFD packet back to the local S-BFD discriminator values, transmit a response S-BFD control
initiator. packet back to the initiator.
Once above setup is complete, any network nodes, having the knowledge Once above setup is complete, any network nodes, having the knowledge
of the mapping from a remote entity to an S-BFD discriminator, can of the mapping from a remote entity to an S-BFD discriminator, can
quickly perform a continuity test to the remote entity by simply quickly perform a continuity test to the remote entity by simply
sending S-BFD packets with corresponding S-BFD discriminator value in sending S-BFD control packets with corresponding S-BFD discriminator
the "your discriminator" field. value in the "your discriminator" field.
For example: For example:
<------- IS-IS Network -------> <------- IS-IS Network ------->
+---------+ +---------+
| | | |
A---------B---------C---------D A---------B---------C---------D
^ ^ ^ ^
| | | |
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123 456 123 456
Figure 2: S-BFD for IS-IS Network Figure 2: S-BFD for IS-IS Network
The IS-IS with SystemID xxx (node A) allocates an S-BFD discriminator The IS-IS with SystemID xxx (node A) allocates an S-BFD discriminator
123, and advertises the S-BFD discriminator 123 in an IS-IS TLV. The 123, and advertises the S-BFD discriminator 123 in an IS-IS TLV. The
IS-IS with SystemID yyy (node D) allocates an S-BFD discriminator IS-IS with SystemID yyy (node D) allocates an S-BFD discriminator
456, and advertises the S-BFD discriminator 456 in an IS-IS TLV. A 456, and advertises the S-BFD discriminator 456 in an IS-IS TLV. A
reflector BFD session is created on both network nodes (node A and reflector BFD session is created on both network nodes (node A and
node D). When network node A wants to check the reachability to node D). When network node A wants to check the reachability to
network node D, node A can send an S-BFD packet, destined to node D, network node D, node A can send an S-BFD control packet, destined to
with "your discriminator" field set to 456. When the reflector BFD node D, with "your discriminator" field set to 456. When the
session on node D receives this S-BFD packet, then response S-BFD reflector BFD session on node D receives this S-BFD control packet,
packet is sent back to node A, which allows node A to complete the then response S-BFD control packet is sent back to node A, which
continuity test. allows node A to complete the continuity test.
4. S-BFD Discriminators 4. S-BFD Discriminators
4.1. Discriminator Pools 4.1. S-BFD Discriminator Uniqueness
This document defines following suggestions for discriminator One important characteristics of an S-BFD discriminator is that it
management on SBFDInitiator and SBFDReflector sessions, to minimize MUST be unique within an administrative domain. If multiple network
the collision between required S-BFD discriminators on a local nodes allocated a same S-BFD discriminator value, then S-BFD control
device. packets falsely terminating on a wrong network node can result in a
reflector BFD session to generate a response back, due to "your
discriminator" matching. This is clearly not desirable. If only IP
based S-BFD is considered, then it is possible for the reflector BFD
session to require demultiplexing of incoming S-BFD control packets
with combination of destination IP address and "your discriminator".
Then S-BFD discriminator only has to be unique within a local node.
However, S-BFD is a generic mechanism defined to run on wide range of
environments: IP, MPLS, etc. For other transports like MPLS, because
of the need to use non-routable IP destination address, it is not
possible for reflector BFD session to demultiplex using IP
destination address. With PHP, there may not be any incoming label
stack to aid in demultiplexing either. Thus, S-BFD imposes a
requirement that S-BFD discriminators MUST be unique within an
administrative domain.
4.2. Discriminator Pools
This subsection describes a discriminator pool implementation
technique to minimize S-BFD discriminator collisions. The result
will allow an implementation to better satisfy the S-BFD
discriminator uniqueness requirement defined in Section 4.1.
o SBFDInitiator is to allocate a discriminator from the BFD o SBFDInitiator is to allocate a discriminator from the BFD
discriminator pool. If the system also supports classical BFD discriminator pool. If the system also supports classical BFD
that runs on [RFC5880], then the BFD discriminator pool SHOULD be that runs on [RFC5880], then the BFD discriminator pool SHOULD be
shared by SBFDInitiator sessions and classical BFD sessions. shared by SBFDInitiator sessions and classical BFD sessions.
o SBFDReflector is to allocate a discriminator from the S-BFD o SBFDReflector is to allocate a discriminator from the S-BFD
discriminator pool. The S-BFD discriminator pool SHOULD be a discriminator pool. The S-BFD discriminator pool SHOULD be a
separate pool than the BFD discriminator pool. separate pool than the BFD discriminator pool.
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Even when following the separate discriminator pool approach, Even when following the separate discriminator pool approach,
collision is still possible between one S-BFD application to another collision is still possible between one S-BFD application to another
S-BFD application, that may be using different values and algorithms S-BFD application, that may be using different values and algorithms
to derive S-BFD discriminator values. If the two applications are to derive S-BFD discriminator values. If the two applications are
using S-BFD for a same purpose (ex: network reachability), then the using S-BFD for a same purpose (ex: network reachability), then the
colliding S-BFD discriminator value can be shared. If the two colliding S-BFD discriminator value can be shared. If the two
applications are using S-BFD for a different purpose, then the applications are using S-BFD for a different purpose, then the
collision must be addressed. How such collisions are addressed is collision must be addressed. How such collisions are addressed is
outside the scope of this document. outside the scope of this document.
4.2. S-BFD Discriminator Uniqueness
One important characteristics of an S-BFD discriminator is that it
MUST be unique within an administrative domain. If multiple network
nodes allocated a same S-BFD discriminator value, then S-BFD packets
falsely terminating on a wrong network node can result in a reflector
BFD session to generate a response back, due to "your discriminator"
matching. This is clearly not desirable. If only IP based S-BFD is
considered, then it is possible for the reflector BFD session to
require demultiplexing of incoming S-BFD packets with combination of
destination IP address and "your discriminator". Then S-BFD
discriminator only has to be unique within a local node. However,
S-BFD is a generic mechanism defined to run on wide range of
environments: IP, MPLS, etc. For other transports like MPLS, because
of the need to use non-routable IP destination address, it is not
possible for reflector BFD session to demultiplex using IP
destination address. With PHP, there may not be any incoming label
stack to aid in demultiplexing either. Thus, S-BFD imposes a
requirement that S-BFD discriminators MUST be unique within an
administrative domain.
5. Reflector BFD Session 5. Reflector BFD Session
Each network node creates one or more reflector BFD sessions. This Each network node creates one or more reflector BFD sessions. This
reflector BFD session is a session which transmits S-BFD packets in reflector BFD session is a session which transmits S-BFD control
response to received S-BFD packets with "your discriminator" having packets in response to received S-BFD control packets with "your
S-BFD discriminators allocated for local entities. Specifically, discriminator" having S-BFD discriminators allocated for local
this reflector BFD session is to have following characteristics: entities. Specifically, this reflector BFD session is to have
following characteristics:
o MUST NOT transmit any S-BFD packets based on local timer expiry. o MUST NOT transmit any S-BFD packets based on local timer expiry.
o MUST transmit an S-BFD packet in response to a received S-BFD o MUST transmit an S-BFD control packet in response to a received
packet having a valid S-BFD discriminator in the "your S-BFD control packet having a valid S-BFD discriminator in the
discriminator" field, unless prohibited by local policies (ex: "your discriminator" field, unless prohibited by local policies
administrative, security, rate-limiter, etc). (ex: administrative, security, rate-limiter, etc).
o MUST be capable of sending only two states: UP and ADMINDOWN. o MUST be capable of sending only two states: UP and ADMINDOWN.
One reflector BFD session may be responsible for handling received One reflector BFD session may be responsible for handling received
S-BFD packets targeted to all locally allocated S-BFD discriminators, S-BFD control packets targeted to all locally allocated S-BFD
or few reflector BFD sessions may each be responsible for subset of discriminators, or few reflector BFD sessions may each be responsible
locally allocated S-BFD discriminators. This policy is a local for subset of locally allocated S-BFD discriminators. This policy is
matter, and is outside the scope of this document. a local matter, and is outside the scope of this document.
Note that incoming S-BFD packets may be IPv4, IPv6 or MPLS based. Note that incoming S-BFD control packets may be IPv4, IPv6 or MPLS
How such S-BFD packets reach an appropriate reflector BFD session is based. How such S-BFD control packets reach an appropriate reflector
also a local matter, and is outside the scope of this document. BFD session is also a local matter, and is outside the scope of this
document.
6. State Variables 6. State Variables
S-BFD introduces new state variables, and modifies the usage of S-BFD introduces new state variables, and modifies the usage of
existing ones. existing ones.
6.1. New State Variables 6.1. New State Variables
A new state variable is added to the base specification in support of A new state variable is added to the base specification in support of
S-BFD. S-BFD.
o bfd.SessionType: The type of this session. Allowable values are: o bfd.SessionType: This is a variable introduced by
[I-D.ietf-bfd-multipoint] and describes the type of this session.
Allowable values for S-BFD sessions are:
* SBFDInitiator - an S-BFD session on a network node that * SBFDInitiator - an S-BFD session on a network node that
performs a continuity test to a target entity by sending S-BFD performs a continuity test to a target entity by sending S-BFD
packets. packets.
* SBFDReflector - an S-BFD session on a network node that listens * SBFDReflector - an S-BFD session on a network node that listens
for incoming S-BFD packets to local entities and generates for incoming S-BFD control packets to local entities and
response S-BFD packets. generates response S-BFD control packets.
bfd.SessionType variable MUST be initialized to the appropriate type bfd.SessionType variable MUST be initialized to the appropriate type
when an S-BFD session is created. when an S-BFD session is created.
6.2. State Variable Initialization and Maintenance 6.2. State Variable Initialization and Maintenance
Some state variables defined in section 6.8.1 of the BFD base Some state variables defined in section 6.8.1 of the BFD base
specification need to be initialized or manipulated differently specification need to be initialized or manipulated differently
depending on the session type. depending on the session type.
o bfd.DemandMode: This variable MUST be initialized to 1 for session o bfd.DemandMode: This variable MUST be initialized to 1 for session
type SBFDInitiator, and MUST be initialized to 0 for session type type SBFDInitiator, and MUST be initialized to 0 for session type
SBFDReflector. SBFDReflector.
7. S-BFD Procedures 7. S-BFD Procedures
7.1. S-BFD Packet Demultiplexing 7.1. S-BFD Control Packet Demultiplexing
Received BFD control packet MUST first be demultiplexed with Received BFD control packet MUST first be demultiplexed with
information from the lower layer (ex: destination UDP port, information from the lower layer (ex: destination UDP port,
associated channel type). If the packet is determined to be for an associated channel type). If the packet is determined to be for an
SBFDReflector, then the packet MUST be looked up to locate a SBFDReflector, then the packet MUST be looked up to locate a
corresponding SBFDReflector session based on the value from the "your corresponding SBFDReflector session based on the value from the "your
discriminator" field in the table describing S-BFD discriminators. discriminator" field in the table describing S-BFD discriminators.
If the packet is determined not to be for SBFDReflector, then the If the packet is determined not to be for SBFDReflector, then the
packet MUST be looked up to locate a corresponding SBFDInitiator packet MUST be looked up to locate a corresponding SBFDInitiator
session or classical BFD session based on the value from the "your session or classical BFD session based on the value from the "your
discriminator" field in the table describing BFD discriminators. If discriminator" field in the table describing BFD discriminators. If
the located session is a SBFDInitiator, then destination of the the located session is a SBFDInitiator, then destination of the
packet (i.e. destination IP address) SHOULD be validated to be for packet (i.e. destination IP address) SHOULD be validated to be for
self. self.
Details of the initial BFD control packet demultiplexing are Details of the initial BFD control packet demultiplexing are
described in relevant S-BFD data plane documents. described in relevant S-BFD data plane documents.
7.2. Initiator Procedures 7.2. Initiator Procedures
S-BFD packets transmitted by an SBFDInitiator MUST set "your S-BFD control packets transmitted by an SBFDInitiator MUST set "your
discriminator" field to an S-BFD discriminator corresponding to the discriminator" field to an S-BFD discriminator corresponding to the
remote entity. remote entity.
Every SBFDInitiator MUST have a locally unique "my discriminator" Every SBFDInitiator MUST have a locally unique "my discriminator"
allocated from the BFD discriminator pool. allocated from the BFD discriminator pool.
Below ASCII art describes high level concept of continuity test using Below ASCII art describes high level concept of continuity test using
S-BFD. R2 allocates XX as the S-BFD discriminator for its network S-BFD. R2 allocates XX as the S-BFD discriminator for its network
reachability purpose, and advertises XX to neighbors. ASCII art reachability purpose, and advertises XX to neighbors. ASCII art
shows R1 and R4 performing a continuity test to R2. shows R1 and R4 performing a continuity test to R2.
skipping to change at page 9, line 19 skipping to change at page 9, line 27
|v | v |v | v
R1 ==================== R2[*] ========= R3 ========= R4 R1 ==================== R2[*] ========= R3 ========= R4
| ^ |^ | ^ |^
| | || | | ||
| +-- md=60/yd=XX (ping) --+| | +-- md=60/yd=XX (ping) --+|
| | | |
+---- md=XX/yd=60 (pong) ---+ +---- md=XX/yd=60 (pong) ---+
[*] Reflector BFD session on R2. [*] Reflector BFD session on R2.
=== Links connecting network nodes. === Links connecting network nodes.
--- S-BFD packet traversal. --- S-BFD control packet traversal.
Figure 3: S-BFD Continuity Test Figure 3: S-BFD Continuity Test
7.2.1. SBFDInitiator State Machine 7.2.1. SBFDInitiator State Machine
An SBFDInitiator may be a persistent session on the initiator with a An SBFDInitiator may be a persistent session on the initiator with a
timer for S-BFD packet transmissions (stateful SBFDInitiator). An timer for S-BFD control packet transmissions (stateful
SBFDInitiator may also be a module, a script or a tool on the SBFDInitiator). An SBFDInitiator may also be a module, a script or a
initiator that transmits one or more S-BFD packets "when needed" tool on the initiator that transmits one or more S-BFD control
(stateless SBFDInitiator). For stateless SBFDInitiators, a complete packets "when needed" (stateless SBFDInitiator). For stateless
BFD state machine may not be applicable. For stateful SBFDInitiators, a complete BFD state machine may not be applicable.
SBFDInitiators, the states and the state machine described in For stateful SBFDInitiators, the states and the state machine
[RFC5880] will not function due to SBFDReflector session only sending described in [RFC5880] will not function due to SBFDReflector session
UP and ADMINDOWN states (i.e. SBFDReflector session does not send only sending UP and ADMINDOWN states (i.e. SBFDReflector session
INIT state). The following diagram provides the RECOMMENDED state does not send INIT state). The following diagram provides the
machine for stateful SBFDInitiators. The notation on each arc RECOMMENDED state machine for stateful SBFDInitiators. The notation
represents the state of the SBFDInitiator (as received in the State on each arc represents the state of the SBFDInitiator (as received in
field in the S-BFD packet) or indicates the expiration of the the State field in the S-BFD control packet) or indicates the
Detection Timer. expiration of the Detection Timer.
+--+ +--+
ADMIN DOWN, | | ADMIN DOWN, | |
TIMER | V TIMER | V
+------+ UP +------+ +------+ UP +------+
| |-------------------->| |----+ | |-------------------->| |----+
| DOWN | | UP | | UP | DOWN | | UP | | UP
| |<--------------------| |<---+ | |<--------------------| |<---+
+------+ ADMIN DOWN, +------+ +------+ ADMIN DOWN, +------+
TIMER TIMER
skipping to change at page 10, line 13 skipping to change at page 10, line 25
Figure 4: SBFDInitiator FSM Figure 4: SBFDInitiator FSM
Note that the above state machine is different from the base BFD Note that the above state machine is different from the base BFD
specification[RFC5880]. This is because the INIT state is no longer specification[RFC5880]. This is because the INIT state is no longer
applicable for the SBFDInitiator. Another important difference is applicable for the SBFDInitiator. Another important difference is
the transition of the state machine from the DOWN state to the UP the transition of the state machine from the DOWN state to the UP
state when a packet with State UP is received by the SBFDInitiator. state when a packet with State UP is received by the SBFDInitiator.
The definitions of the states and the events have the same meaning as The definitions of the states and the events have the same meaning as
in the base BFD specification [RFC5880]. in the base BFD specification [RFC5880].
7.2.2. Details of S-BFD Packet Sent by SBFDInitiator 7.2.2. Details of S-BFD Control Packet Sent by SBFDInitiator
S-BFD packets sent by an SBFDInitiator is to have following contents: S-BFD control packets sent by an SBFDInitiator is to have following
contents:
o "my discriminator" assigned by local node. o "my discriminator" assigned by local node.
o "your discriminator" corresponding to a remote entity. o "your discriminator" corresponding to a remote entity.
o "State" MUST be set to a value describing local state. o "State" MUST be set to a value describing local state.
o "Desired Min TX Interval" MUST be set to a value describing local o "Desired Min TX Interval" MUST be set to a value describing local
desired minimum transmit interval. desired minimum transmit interval.
o "Required Min RX Interval" MUST be zero. o "Required Min RX Interval" MUST be zero.
o "Required Min Echo RX Interval" SHOULD be zero. o "Required Min Echo RX Interval" SHOULD be zero.
o "Detection Multiplier" MUST be set to a value describing locally o "Detection Multiplier" MUST be set to a value describing locally
used multiplier value. used multiplier value.
o Demand (D) bit MUST be set. o Demand (D) bit MUST be set.
7.3. Responder Procedures 7.3. Responder Procedures
A network node which receives S-BFD packets transmitted by an A network node which receives S-BFD control packets transmitted by an
initiator is referred as responder. The responder, upon reception of initiator is referred as responder. The responder, upon reception of
S-BFD packets, is to perform necessary relevant validations described S-BFD control packets, is to perform necessary relevant validations
in [RFC5880], [RFC5881], [RFC5883], [RFC5884] and [RFC5885]. described in [RFC5880], [RFC5881], [RFC5883], [RFC5884] and
[RFC5885].
7.3.1. Responder Demultiplexing 7.3.1. Responder Demultiplexing
When a responder receives an S-BFD packet, if the value in the "your When a responder receives an S-BFD control packet, if the value in
discriminator" field is not one of S-BFD discriminators allocated for the "your discriminator" field is not one of S-BFD discriminators
local entities, then this packet MUST NOT be considered for this allocated for local entities, then this packet MUST NOT be considered
mechanism. If the value in the "your discriminator" field is one of for this mechanism. If the value in the "your discriminator" field
S-BFD discriminators allocated for local entities, then the packet is is one of S-BFD discriminators allocated for local entities, then the
determined to be handled by a reflector BFD session responsible for packet is determined to be handled by a reflector BFD session
the S-BFD discriminator. If the packet was determined to be responsible for the S-BFD discriminator. If the packet was
processed further for this mechanism, then chosen reflector BFD determined to be processed further for this mechanism, then chosen
session is to transmit a response BFD control packet using procedures reflector BFD session is to transmit a response BFD control packet
described in Section 7.3.2, unless prohibited by local policies (ex: using procedures described in Section 7.3.2, unless prohibited by
administrative, security, rate-limiter, etc). local policies (ex: administrative, security, rate-limiter, etc).
7.3.2. Details of S-BFD Packet Sent by SBFDReflector 7.3.2. Details of S-BFD Control Packet Sent by SBFDReflector
S-BFD packets sent by an SBFDReflector is to have following contents: S-BFD control packets sent by an SBFDReflector is to have following
contents:
o "my discriminator" MUST be copied from received "your o "my discriminator" MUST be copied from received "your
discriminator". discriminator".
o "your discriminator" MUST be copied from received "my o "your discriminator" MUST be copied from received "my
discriminator". discriminator".
o "State" MUST be UP or ADMINDOWN. Clarification of reflector BFD o "State" MUST be UP or ADMINDOWN. Clarification of reflector BFD
session state is described in Section 7.8. session state is described in Section 7.8.
o "Desired Min TX Interval" MUST be copied from received "Desired o "Desired Min TX Interval" MUST be copied from received "Desired
Min TX Interval". Min TX Interval".
o "Required Min RX Interval" MUST be set to a value describing how o "Required Min RX Interval" MUST be set to a value describing how
skipping to change at page 11, line 35 skipping to change at page 11, line 50
7.4. Diagnostic Values 7.4. Diagnostic Values
Diagnostic value in both directions MAY be set to a certain value, to Diagnostic value in both directions MAY be set to a certain value, to
attempt to communicate further information to both ends. However, attempt to communicate further information to both ends. However,
details of such are outside the scope of this specification. details of such are outside the scope of this specification.
7.5. The Poll Sequence 7.5. The Poll Sequence
Poll sequence MAY be used in both directions. The Poll sequence MUST Poll sequence MAY be used in both directions. The Poll sequence MUST
operate in accordance with [RFC5880]. An SBFDReflector MAY use the operate in accordance with [RFC5880]. An SBFDReflector MAY use the
Poll sequence to slow down that rate at which S-BFD packets are Poll sequence to slow down that rate at which S-BFD control packets
generated from an SBFDInitiator. This is done by the SBFDReflector are generated from an SBFDInitiator. This is done by the
using procedures described in Section 7.8 and setting the Poll (P) SBFDReflector using procedures described in Section 7.8 and setting
bit in the reflected S-BFD packet. The SBFDInitiator is to then send the Poll (P) bit in the reflected S-BFD control packet. The
the next S-BFD packet with the Final (F) bit set. If an SBFDInitiator is to then send the next S-BFD control packet with the
SBFDReflector receives an S-BFD packet with Poll (P) bit set, then Final (F) bit set. If an SBFDReflector receives an S-BFD control
the SBFDReflector MUST respond with an S-BFD packet with Poll (P) bit packet with Poll (P) bit set, then the SBFDReflector MUST respond
cleared and Final (F) bit set. with an S-BFD control packet with Poll (P) bit cleared and Final (F)
bit set.
7.6. Control Plane Independent (C) 7.6. Control Plane Independent (C)
Control plane independent (C) bit for an SBFDInitiator sending S-BFD Control plane independent (C) bit for an SBFDInitiator sending S-BFD
packets to a reflector BFD session MUST work according to [RFC5880]. control packets to a reflector BFD session MUST work according to
Reflector BFD session also MUST work according to [RFC5880]. [RFC5880]. Reflector BFD session also MUST work according to
Specifically, if reflector BFD session implementation does not share [RFC5880]. Specifically, if reflector BFD session implementation
fate with control plane, then response S-BFD packets transmitted MUST does not share fate with control plane, then response S-BFD control
have control plane independent (C) bit set. If reflector BFD session packets transmitted MUST have control plane independent (C) bit set.
implementation shares fate with control plane, then response S-BFD If reflector BFD session implementation shares fate with control
packets transmitted MUST NOT have control plane independent (C) bit plane, then response S-BFD control packets transmitted MUST NOT have
set. control plane independent (C) bit set.
7.7. Additional SBFDInitiator Behaviors 7.7. Additional SBFDInitiator Behaviors
o If the SBFDInitiator receives a valid S-BFD packet in response to o If the SBFDInitiator receives a valid S-BFD control packet in
transmitted S-BFD packet to a remote entity, then the response to transmitted S-BFD control packet to a remote entity,
SBFDInitiator SHOULD conclude that S-BFD packet reached the then the SBFDInitiator SHOULD conclude that S-BFD control packet
intended remote entity. reached the intended remote entity.
o When a sufficient number of S-BFD packets have not arrived as they o When a sufficient number of S-BFD packets have not arrived as they
should, the SBFDInitiator SHOULD declare loss of reachability to should, the SBFDInitiator SHOULD declare loss of reachability to
the remote entity. The criteria for declaring loss of the remote entity. The criteria for declaring loss of
reachability and the action that would be triggered as a result reachability and the action that would be triggered as a result
are outside the scope of this document. are outside the scope of this document.
o Relating to above bullet item, it is critical for an o Relating to above bullet item, it is critical for an
implementation to understand the latency to/from the reflector BFD implementation to understand the latency to/from the reflector BFD
session on the responder. In other words, for very first S-BFD session on the responder. In other words, for very first S-BFD
packet transmitted by the SBFDInitiator, an implementation MUST packet transmitted by the SBFDInitiator, an implementation MUST
NOT expect response S-BFD packet to be received for time NOT expect response S-BFD packet to be received for time
equivalent to sum of latencies: initiator to responder and equivalent to sum of latencies: initiator to responder and
responder back to initiator. responder back to initiator.
o If the SBFDInitiator receives an S-BFD packet with Demand (D) bit o If the SBFDInitiator receives an S-BFD control packet with Demand
set, the packet MUST be discarded. (D) bit set, the packet MUST be discarded.
7.8. Additional SBFDReflector Behaviors 7.8. Additional SBFDReflector Behaviors
o S-BFD packets transmitted by the SBFDReflector MUST have "Required o S-BFD control packets transmitted by the SBFDReflector MUST have
Min RX Interval" set to a value which expresses how many incoming "Required Min RX Interval" set to a value which expresses how many
S-BFD packets this SBFDReflector can handle. The SBFDReflector incoming S-BFD control packets this SBFDReflector can handle. The
can control how fast SBFInitiators will be sending S-BFD packets SBFDReflector can control how fast SBFInitiators will be sending
to self by ensuring "Required Min RX Interval" indicates a value S-BFD control packets to self by ensuring "Required Min RX
based on the current load. Interval" indicates a value based on the current load.
o If the SBFDReflector wishes to communicate to some or all o If the SBFDReflector wishes to communicate to some or all
SBFDInitiators that monitored local entity is "temporarily out of SBFDInitiators that monitored local entity is "temporarily out of
service", then S-BFD packets with "state" set to ADMINDOWN are service", then S-BFD control packets with "state" set to ADMINDOWN
sent to those SBFDInitiators. The SBFDInitiators, upon reception are sent to those SBFDInitiators. The SBFDInitiators, upon
of such packets, MUST NOT conclude loss of reachability to reception of such packets, MUST NOT conclude loss of reachability
corresponding remote entity, and MUST back off packet transmission to corresponding remote entity, and MUST back off packet
interval for the remote entity to an interval no faster than 1 transmission interval for the remote entity to an interval no
second. If the SBFDReflector is generating a response S-BFD faster than 1 second. If the SBFDReflector is generating a
packet for a local entity that is in service, then "state" in response S-BFD control packet for a local entity that is in
response BFD control packets MUST be set to UP. service, then "state" in response BFD control packets MUST be set
to UP.
o If an SBFDReflector receives an S-BFD packet with Demand (D) bit o If an SBFDReflector receives an S-BFD control packet with Demand
cleared, the packet MUST be discarded. (D) bit cleared, the packet MUST be discarded.
8. Scaling Aspect 8. Scaling Aspect
This mechanism brings forth one noticeable difference in terms of This mechanism brings forth one noticeable difference in terms of
scaling aspect: number of SBFDReflector. This specification scaling aspect: number of SBFDReflector. This specification
eliminates the need for egress nodes to have fully active BFD eliminates the need for egress nodes to have fully active BFD
sessions when only one side desires to perform continuity tests. sessions when only one side desires to perform continuity tests.
With introduction of reflector BFD concept, egress no longer is With introduction of reflector BFD concept, egress no longer is
required to create any active BFD session per path/LSP/function required to create any active BFD session per path/LSP/function
basis. Due to this, total number of BFD sessions in a network is basis. Due to this, total number of BFD sessions in a network is
skipping to change at page 13, line 28 skipping to change at page 13, line 43
9. Co-existence with Classical BFD Sessions 9. Co-existence with Classical BFD Sessions
Initial packet demultiplexing requirement is described in Initial packet demultiplexing requirement is described in
Section 7.1. Because of this, S-BFD mechanism can co-exist with Section 7.1. Because of this, S-BFD mechanism can co-exist with
classical BFD sessions. classical BFD sessions.
10. S-BFD Echo Function 10. S-BFD Echo Function
The concept of the S-BFD Echo function is similar to the BFD Echo The concept of the S-BFD Echo function is similar to the BFD Echo
function described in [RFC5880], packets are self-generated and self- function described in [RFC5880]. S-BFD echo packets have the
terminated after traversing a link/path. S-BFD echo packets are destination of self, thus S-BFD echo packets are self-generated and
self-terminated after traversing a link/path. S-BFD echo packets are
expected to u-turn on the target node in the data plane and MUST NOT expected to u-turn on the target node in the data plane and MUST NOT
be processed by any reflector BFD sessions on the target node. be processed by any reflector BFD sessions on the target node.
When using the S-BFD Echo function, it is RECOMMENDED that: When using the S-BFD Echo function, it is RECOMMENDED that:
o Both S-BFD packets (with BFD control header) and S-BFD echo o Both S-BFD control packets and S-BFD echo packets be sent.
packets (implementation specific) be sent.
o Both S-BFD packets and S-BFD echo packets have the same semantics o Both S-BFD control packets and S-BFD echo packets have the same
in the forward direction to reach the target node. semantics in the forward direction to reach the target node.
In other words, it is not preferable to send just S-BFD echo packets. In other words, it is not preferable to send just S-BFD echo packets
There are two reason behind this suggestion: without also sending S-BFD control packets. There are two reasons
behind this suggestion:
o S-BFD packets can verify reachability to intended target node, o S-BFD control packets can verify the reachability to intended
which allows one to conclude that S-BFD echo packets are u-turning target node, which allows one to have confidence that S-BFD echo
on the expected target node. packets are u-turning on the expected target node.
o S-BFD packets can detect when the target node is going out of o S-BFD control packets can detect when the target node is going out
service (i.e. via receiving back ADMINDOWN state). of service (i.e. via receiving back ADMINDOWN state).
Implementations MAY set "Required Min Echo RX Interval" field to The usage of the "Required Min Echo RX Interval" field is described
indicate the rate which SBFDInitiator is sending S-BFD Echo packets in Section 7.2.2 and Section 7.3.2. Because of the stateless nature
(in ping) or the rate which SBFDReflector wants SBFDInitiators to of SBFDReflector sessions, a value specified the "Required Min Echo
send S-BFD Echo packets (in pong). However, this is likely more than RX Interval" field in both directions is not very meaningful. Thus
necessary for the S-BFD Echo function to operate. Therefore, it is it is RECOMMENDED that the "Required Min Echo RX Interval" field
RECOMMENDED that "Required Min Echo RX Interval" field simply be set simply be set to zero in both directions.
to zero in both directions.
Additionally, following aspects are left as implementation details, Following aspects of S-BFD Echo functions are left as implementation
and are outside the scope of this document: details, and are outside the scope of this document:
o Format of the S-BFD Echo packet (ex: data beyond UDP header). o Format of the S-BFD echo packet (ex: data beyond UDP header).
o Procedures on when and how to use the S-BFD Echo function. o Procedures on when and how to use the S-BFD Echo function.
11. Security Considerations 11. Security Considerations
Same security considerations as [RFC5880], [RFC5881], [RFC5883], Same security considerations as [RFC5880], [RFC5881], [RFC5883],
[RFC5884] and [RFC5885] apply to this document. Additionally, [RFC5884] and [RFC5885] apply to this document. Additionally,
implementing the following measures will strengthen security aspects implementing the following measures will strengthen security aspects
of the mechanism described by this document: of the mechanism described by this document:
skipping to change at page 14, line 38 skipping to change at page 15, line 6
accepting the packet. accepting the packet.
o SBFDReflector MAY look at the Key ID o SBFDReflector MAY look at the Key ID
[I-D.ietf-bfd-generic-crypto-auth] in the incoming packet and [I-D.ietf-bfd-generic-crypto-auth] in the incoming packet and
verify the authentication data. verify the authentication data.
o SBFDReflector MUST accept the packet if authentication is o SBFDReflector MUST accept the packet if authentication is
successful. successful.
o SBFDReflector MUST compute the Authentication data and MUST use o SBFDReflector MUST compute the Authentication data and MUST use
the same sequence number that it received in the S-BFD packet that the same sequence number that it received in the S-BFD control
it is responding to. packet that it is responding to.
o SBFDInitiator MUST accept the S-BFD packet if it either comes with o SBFDInitiator MUST accept the S-BFD control packet if it either
the same sequence number as it had sent or it's within the window comes with the same sequence number as it had sent or it's within
that it finds acceptable (described in detail in the window that it finds acceptable (described in detail in
[I-D.ietf-bfd-generic-crypto-auth]) [I-D.ietf-bfd-generic-crypto-auth])
Using the above method, Using the above method,
o SBFDReflector continue to remain stateless despite using security. o SBFDReflector continue to remain stateless despite using security.
o SBFDReflector are not susceptible to replay attacks as they always o SBFDReflector are not susceptible to replay attacks as they always
respond to S-BFD packets irrespective of the sequence number respond to S-BFD control packets irrespective of the sequence
carried. number carried.
o An attacker cannot impersonate the responder since the o An attacker cannot impersonate the responder since the
SBFDInitiator will only accept S-BFD packets that come with the SBFDInitiator will only accept S-BFD control packets that come
sequence number that it had originally used when sending the S-BFD with the sequence number that it had originally used when sending
packet. the S-BFD control packet.
12. IANA Considerations 12. IANA Considerations
No action is required by IANA for this document. No action is required by IANA for this document.
13. Acknowledgements 13. Acknowledgements
Authors would like to thank Jeffrey Haas, Greg Mirsky and Marc Authors would like to thank Jeffrey Haas, Greg Mirsky and Marc
Binderberger for performing thorough reviews and providing number of Binderberger for performing thorough reviews and providing number of
suggestions. Authors would like to thank Girija Raghavendra Rao, Les suggestions. Authors would like to thank Girija Raghavendra Rao, Les
skipping to change at page 16, line 33 skipping to change at page 16, line 42
"Bidirectional Forwarding Detection (BFD) for MPLS Label "Bidirectional Forwarding Detection (BFD) for MPLS Label
Switched Paths (LSPs)", RFC 5884, June 2010. Switched Paths (LSPs)", RFC 5884, June 2010.
15.2. Informative References 15.2. Informative References
[I-D.ietf-bfd-generic-crypto-auth] [I-D.ietf-bfd-generic-crypto-auth]
Bhatia, M., Manral, V., Zhang, D., and M. Jethanandani, Bhatia, M., Manral, V., Zhang, D., and M. Jethanandani,
"BFD Generic Cryptographic Authentication", draft-ietf- "BFD Generic Cryptographic Authentication", draft-ietf-
bfd-generic-crypto-auth-06 (work in progress), April 2014. bfd-generic-crypto-auth-06 (work in progress), April 2014.
[I-D.ietf-bfd-multipoint]
Katz, D., Ward, D., and J. Networks, "BFD for Multipoint
Networks", draft-ietf-bfd-multipoint-04 (work in
progress), August 2014.
[I-D.ietf-bfd-seamless-use-case] [I-D.ietf-bfd-seamless-use-case]
Aldrin, S., Bhatia, M., Mirsky, G., Kumar, N., and S. Aldrin, S., Bhatia, M., Mirsky, G., Kumar, N., and S.
Matsushima, "Seamless Bidirectional Forwarding Detection Matsushima, "Seamless Bidirectional Forwarding Detection
(BFD) Use Case", draft-ietf-bfd-seamless-use-case-00 (work (BFD) Use Case", draft-ietf-bfd-seamless-use-case-00 (work
in progress), June 2014. in progress), June 2014.
[RFC5885] Nadeau, T. and C. Pignataro, "Bidirectional Forwarding [RFC5885] Nadeau, T. and C. Pignataro, "Bidirectional Forwarding
Detection (BFD) for the Pseudowire Virtual Circuit Detection (BFD) for the Pseudowire Virtual Circuit
Connectivity Verification (VCCV)", RFC 5885, June 2010. Connectivity Verification (VCCV)", RFC 5885, June 2010.
skipping to change at page 18, line 27 skipping to change at page 18, line 36
Dave Ward Dave Ward
Cisco Systems Cisco Systems
Email: wardd@cisco.com Email: wardd@cisco.com
Manav Bhatia Manav Bhatia
Ionos Networks Ionos Networks
Email: manav@ionosnetworks.com Email: manav@ionosnetworks.com
Santosh Santosh Pallagatti
Juniper Networks Juniper Networks
Email: santoshpk@juniper.net Email: santoshpk@juniper.net
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