draft-ietf-bfd-rfc5884-clarifications-03.txt   draft-ietf-bfd-rfc5884-clarifications-04.txt 
Internet Engineering Task Force V. Govindan Internet Engineering Task Force V. Govindan
Internet-Draft K. Rajaraman Internet-Draft K. Rajaraman
Updates: 5884 (if approved) Cisco Systems Updates: 5884 (if approved) Cisco Systems
Intended status: Standards Track G. Mirsky Intended status: Standards Track G. Mirsky
Expires: April 5, 2016 Ericsson Expires: April 16, 2016 Ericsson
N. Akiya N. Akiya
Big Switch Networks Big Switch Networks
S. Aldrin S. Aldrin
Google Google
October 3, 2015 October 14, 2015
Clarifications to RFC 5884 Clarifications to RFC 5884
draft-ietf-bfd-rfc5884-clarifications-03 draft-ietf-bfd-rfc5884-clarifications-04
Abstract Abstract
This document clarifies the procedures for establishing, maintaining This document clarifies the procedures for establishing, maintaining
and removing multiple, concurrent BFD sessions for a given <MPLS LSP, and removing multiple, concurrent BFD (Bidirectional Forwarding
FEC> described in RFC5884. Detection) sessions for a given <MPLS LSP, FEC> described in RFC5884.
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 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 April 5, 2016. This Internet-Draft will expire on April 16, 2016.
Copyright Notice Copyright Notice
Copyright (c) 2015 IETF Trust and the persons identified as the Copyright (c) 2015 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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described in the Simplified BSD License. described in the Simplified BSD License.
Table of Contents Table of Contents
1. Background . . . . . . . . . . . . . . . . . . . . . . . . . 2 1. Background . . . . . . . . . . . . . . . . . . . . . . . . . 2
1.1. Requirements Language . . . . . . . . . . . . . . . . . . 2 1.1. Requirements Language . . . . . . . . . . . . . . . . . . 2
2. Theory of Operation . . . . . . . . . . . . . . . . . . . . . 3 2. Theory of Operation . . . . . . . . . . . . . . . . . . . . . 3
2.1. Procedures for establishment of multiple BFD sessions . . 3 2.1. Procedures for establishment of multiple BFD sessions . . 3
2.2. Procedures for maintenance of multiple BFD sessions . . . 4 2.2. Procedures for maintenance of multiple BFD sessions . . . 4
2.3. Procedures for removing BFD sessions at the egress LSR . 4 2.3. Procedures for removing BFD sessions at the egress LSR . 4
2.4. Changing discriminators for a BFD session . . . . . . . . 4 2.4. Changing discriminators for a BFD session . . . . . . . . 5
3. Backwards Compatibility . . . . . . . . . . . . . . . . . . . 5 3. Backwards Compatibility . . . . . . . . . . . . . . . . . . . 5
4. Security Considerations . . . . . . . . . . . . . . . . . . . 5 4. Security Considerations . . . . . . . . . . . . . . . . . . . 5
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 5 5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 5
6. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 5 6. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 5
7. Normative References . . . . . . . . . . . . . . . . . . . . 5 7. Normative References . . . . . . . . . . . . . . . . . . . . 6
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 6 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 6
1. Background 1. Background
[RFC5884] defines the procedures to bootstrap and maintain BFD [RFC5884] defines the procedures to bootstrap and maintain BFD
sessions for a <MPLS FEC, LSP> using LSP ping. While Section 4 of sessions for a <MPLS FEC, LSP> using LSP ping. While Section 4 of
[RFC5884] specifies that multiple BFD sessions can be established for [RFC5884] specifies that multiple BFD sessions can be established for
a <MPLS FEC, LSP> tuple, the procedures to bootstrap and maintain a <MPLS FEC, LSP> tuple, the procedures to bootstrap and maintain
multiple BFD sessions concurrently over a <MPLS FEC, LSP> are not multiple BFD sessions concurrently over a <MPLS FEC, LSP> are not
clearly specified. Additionally, the procedures of removing BFD clearly specified. Additionally, the procedures of removing BFD
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2.3. Procedures for removing BFD sessions at the egress LSR 2.3. Procedures for removing BFD sessions at the egress LSR
[RFC5884] does not specify an explicit procedure for deleting BFD [RFC5884] does not specify an explicit procedure for deleting BFD
sessions. The procedure for removing a BFD session established by an sessions. The procedure for removing a BFD session established by an
out-of-band discriminator exchange using the MPLS LSP ping can out-of-band discriminator exchange using the MPLS LSP ping can
improve resource management (like memory etc.) especially in improve resource management (like memory etc.) especially in
scenarios involving thousands or more of such sessions. A few scenarios involving thousands or more of such sessions. A few
observations are made here: observations are made here:
The BFD session MAY be removed in the egress LSR if the BFD The BFD session MAY be removed in the egress LSR if the BFD
session transitions from UP to DOWN. This can be done after the session transitions from UP to DOWN. This can either be done
expiry of a configurable timer started after the BFD session state immediately after the BFD session transitions from UP to DOWN or
transitions from UP to DOWN at the egress LSR. after the expiry of a configurable timer started after the BFD
session state transitions from UP to DOWN at the egress LSR to
reduce flapping by adding hysteresis.
The BFD session on the egress LSR MAY be removed by the ingress The BFD session on the egress LSR MAY be removed by the ingress
LSR by using the BFD diagnostic code AdminDown(7) as specified in LSR by using the BFD diagnostic code AdminDown(7) as specified in
[RFC5880]. When the ingress LSR wants to remove a session without [RFC5880]. When the ingress LSR wants to remove a session without
triggering any state change at the egress, it MAY transmit BFD triggering any state change at the egress, it MAY transmit BFD
packets indicating the State as Down(1), diagnostic code packets indicating the State as Down(1), diagnostic code
AdminDown(7) detectMultiplier number of times. Upon receiving AdminDown(7) detectMultiplier number of times. Upon receiving
such a packet, the egress LSR MAY remove the BFD session, without such a packet, the egress LSR MAY remove the BFD session, without
triggering a change of state. triggering a change of state.
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This document does not make any requests to IANA. This document does not make any requests to IANA.
6. Acknowledgements 6. Acknowledgements
The authors would like to thank Marc Binderberger for performing The authors would like to thank Marc Binderberger for performing
thorough reviews and providing valuable suggestions. thorough reviews and providing valuable suggestions.
The authors would like to thank Mudigonda Mallik, Rajaguru Veluchamy The authors would like to thank Mudigonda Mallik, Rajaguru Veluchamy
and Carlos Pignataro of Cisco Systems for their review comments. and Carlos Pignataro of Cisco Systems for their review comments.
The authors would like to thank Alvaro Retana and Scott Bradner for
their review comments.
7. Normative References 7. Normative References
[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,
<http://www.rfc-editor.org/info/rfc2119>. <http://www.rfc-editor.org/info/rfc2119>.
[RFC4379] Kompella, K. and G. Swallow, "Detecting Multi-Protocol [RFC4379] Kompella, K. and G. Swallow, "Detecting Multi-Protocol
Label Switched (MPLS) Data Plane Failures", RFC 4379, Label Switched (MPLS) Data Plane Failures", RFC 4379,
DOI 10.17487/RFC4379, February 2006, DOI 10.17487/RFC4379, February 2006,
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