Internet DRAFT - draft-tanmir-rtgwg-bfd-mc-lag-mpls
draft-tanmir-rtgwg-bfd-mc-lag-mpls
RTG Working Group G. Mirsky
Internet-Draft ZTE Corp.
Updates: 7130 (if approved) J. Tantsura
Intended status: Standards Track Individual
Expires: September 11, 2017 March 10, 2017
Bidirectional Forwarding Detection (BFD) on Multi-chassis Ling
Aggregation Group (MC-LAG) Interfaces in IP/MPLS Networks
draft-tanmir-rtgwg-bfd-mc-lag-mpls-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
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet-
Drafts is at http://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress."
This Internet-Draft will expire on September 11, 2017.
Copyright Notice
Copyright (c) 2017 IETF Trust and the persons identified as the
document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents
(http://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents
carefully, as they describe your rights and restrictions with respect
to this document. Code Components extracted from this document must
include Simplified BSD License text as described in Section 4.e of
Mirsky & Tantsura Expires September 11, 2017 [Page 1]
Internet-Draft BFD for MC-LAG over IP/MPLS March 2017
the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
1.1. Conventions used in this document . . . . . . . . . . . . 2
1.1.1. Terminology . . . . . . . . . . . . . . . . . . . . . 2
1.1.2. Requirements Language . . . . . . . . . . . . . . . . 3
2. Problem Statement . . . . . . . . . . . . . . . . . . . . . . 3
3. BFD on MC-LAG with IP/MPLS data plane . . . . . . . . . . . . 3
4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 4
5. Security Considerations . . . . . . . . . . . . . . . . . . . 4
6. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 4
7. Normative References . . . . . . . . . . . . . . . . . . . . 4
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 5
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
ACH: Associated Channel Header
BFD: Bidirectional Forwarding Detection
BoS: Bottom of the Stack
G-ACh: Generic Associated Channel
GAL: Generic Associated Label
LAG: Link Aggregation Group
LACP: Link Aggregation Control Protocol
Mirsky & Tantsura Expires September 11, 2017 [Page 2]
Internet-Draft BFD for MC-LAG over IP/MPLS March 2017
MC-LAG: Multi-chassis Link Aggregation Group
MPLS: Multi-Protocol Label Switching
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].
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/MPLS data plane
There are more optional encapsulation formats for the case of micro-
BFD on MC-LAG over IP/MPLS data plane:
o [RFC5586] defined special purpose Generic Associated channel Label
(GAL) that MAY be used in MPLS encapsulation of the micro-BFD
control packet over MPSL data plane. Depending on the channel
type specified in the Associated Channel Header (ACH) that
immediately follows after the GAL, micro-BFD MAY use IP/UDP, as
displayed in Figure 1 or BFD format, i.e. BFD control packet
without IP and UDP headers.
Mirsky & Tantsura Expires September 11, 2017 [Page 3]
Internet-Draft BFD for MC-LAG over IP/MPLS March 2017
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| GAL | TC |1| TTL |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|0 0 0 1|0 0 0 0| Reserved | IPv4 channel (0x0021) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Destination IP address |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Source IP address |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| UDP header |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
~ BFD Control Packet ~
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 1: BFD on MC-LAG member link on IPv4/MPLS data plane
If IP/UDP format of BFD over MC-LAG interfaces is used, then for IPv4
address family the destination IP address MUST be selected from 127/8
range [RFC4379], and if IPv6 address family is used, then the
destination IP address MUST be selected from 0:0:0:0:0:FFFF:127/104
range.
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
7. Normative References
[IEEE.802.1AX.2008]
"IEEE Standard for Local and metropolitan area networks -
Link Aggregation", IEEE 802.1-AX, November 2008.
Mirsky & Tantsura Expires September 11, 2017 [Page 4]
Internet-Draft BFD for MC-LAG over IP/MPLS March 2017
[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>.
[RFC4379] Kompella, K. and G. Swallow, "Detecting Multi-Protocol
Label Switched (MPLS) Data Plane Failures", RFC 4379,
DOI 10.17487/RFC4379, February 2006,
<http://www.rfc-editor.org/info/rfc4379>.
[RFC5586] Bocci, M., Ed., Vigoureux, M., Ed., and S. Bryant, Ed.,
"MPLS Generic Associated Channel", RFC 5586,
DOI 10.17487/RFC5586, June 2009,
<http://www.rfc-editor.org/info/rfc5586>.
[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
Individual
Email: jefftant.ietf@gmail.com
Mirsky & Tantsura Expires September 11, 2017 [Page 5]
