Internet DRAFT - draft-tanmir-rtgwg-bfd-mc-lag-ip
draft-tanmir-rtgwg-bfd-mc-lag-ip
RTG Working Group G. Mirsky
Internet-Draft ZTE Corp.
Updates: 7130 (if approved) J. Tantsura
Intended status: Standards Track Indvidual
Expires: September 11, 2017 March 10, 2017
Bidirectional Forwarding Detection (BFD) on Multi-chassis Ling
Aggregation Group (MC-LAG) Interfaces in IP Networks
draft-tanmir-rtgwg-bfd-mc-lag-ip-01
Abstract
This document describes use of Bidirectional Forwarding Detection for
Multi-chassis Link Aggregation Group to provide faster than Link
Aggregation Control Protocol convergence. This specification
enhances and updates RFC 7130 "Bidirectional Forwarding Detection
(BFD) on Link Aggregation Group (LAG) Interfaces".
Status of This Memo
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
1.1. Conventions used in this document . . . . . . . . . . . . 2
1.1.1. Terminology . . . . . . . . . . . . . . . . . . . . . 2
1.1.2. Requirements Language . . . . . . . . . . . . . . . . 2
2. Problem Statement . . . . . . . . . . . . . . . . . . . . . . 3
3. BFD on MC-LAG with IP only data plane . . . . . . . . . . . . 3
4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 3
5. Security Considerations . . . . . . . . . . . . . . . . . . . 3
6. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 3
7. Normative References . . . . . . . . . . . . . . . . . . . . 4
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 4
1. Introduction
The [RFC7130] defines use of Bidirectional Forwarding Detection (BFD)
on Link Aggregation Group (LAG) interfaces. Multi-chassis LAG (MC-
LAG) is type of LAG [IEEE.802.1AX.2008] with member links terminated
on separate chassis. [IEEE.802.1AX.2008] does not specify MC-LAG but
doesn't preclude it either. Link Aggregation Control Protocol
(LACP), also defined in [IEEE.802.1AX.2008], can work with MC-LAG
but, as in LAG case, can detect link failure only in range of single
seconds. This document defines how mechanism defined to work on LAG
interfaces [RFC7130] can be adapted to MC-LAG case to enable sub-
second detection of member link failure.
1.1. Conventions used in this document
1.1.1. Terminology
BFD: Bidirectional Forwarding Detection
LAG: Link Aggregation Group
LACP: Link Aggregation Control Protocol
MC-LAG: Multi-chassis Link Aggregation Group
1.1.2. Requirements Language
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in
[RFC2119].
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2. Problem Statement
[RFC7130] does not specify selection of the destination IP address
for the BFD control packet. The only requirement related to the
selection is in Section 2.1 stating that the use of address family
across all member links of the given LAG MUST be consistent across
all the links. Thus it is implied that the same unicast IP address
will be used on all member links of the LAG as use of different
destination addresses would defeat the purpose of [RFC7130]
transforming the case into set of single-hop BFD sessions [RFC5881].
But single unicast IP address may not work in MC-LAG case as the
member links are terminated on the separate chassis. This document
proposes how to overcome this problem if using IP or Multi-Protocol
Label Switching (MPLS) data plane encapsulation.
3. BFD on MC-LAG with IP only data plane
As described in [RFC7130] micro-BFD session on the LAG interfaces may
use either IPv4 or IPv6 address family. In some cases two sessions,
one with IPv4 and one with IPv6 addresses, may run concurrently.
This document doesn't change any of these but specifies selection of
the destination IP address in MC-LAG use case:
o if IPv4 address family being used for micro-BFD session, then the
link-local multicast address 224.0.0.0/24 SHOULD be used as the
destination IP address. Subnet broadcast address MAY be used as
the destination IP address as well;
o if the address family used is IPv6, then the IPv6 link-local
multicast address FF02:0:0:0:0:0:0:2 MUST be used as the
destination IP address.
4. IANA Considerations
This document makes no requests for IANA allocations. This section
may be deleted by RFC Editor.
5. Security Considerations
Security considerations discussed in [RFC7130] apply to this
document.
6. Acknowledgements
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7. Normative References
[IEEE.802.1AX.2008]
"IEEE Standard for Local and metropolitan area networks -
Link Aggregation", IEEE 802.1-AX, November 2008.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
<http://www.rfc-editor.org/info/rfc2119>.
[RFC5881] Katz, D. and D. Ward, "Bidirectional Forwarding Detection
(BFD) for IPv4 and IPv6 (Single Hop)", RFC 5881,
DOI 10.17487/RFC5881, June 2010,
<http://www.rfc-editor.org/info/rfc5881>.
[RFC7130] Bhatia, M., Ed., Chen, M., Ed., Boutros, S., Ed.,
Binderberger, M., Ed., and J. Haas, Ed., "Bidirectional
Forwarding Detection (BFD) on Link Aggregation Group (LAG)
Interfaces", RFC 7130, DOI 10.17487/RFC7130, February
2014, <http://www.rfc-editor.org/info/rfc7130>.
Authors' Addresses
Greg Mirsky
ZTE Corp.
Email: gregimirsky@gmail.com
Jeff Tantsura
Indvidual
Email: jefftant.ietf@gmail.com
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