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MPLS Working Group G. Mirsky
Internet-Draft ZTE Corp.
Intended status: Standards Track October 12, 2018
Expires: April 15, 2019
BFD for Multipoint Networks over Point-to-Multi-Point MPLS LSP
draft-mirsky-mpls-p2mp-bfd-04
Abstract
This document describes procedures for using Bidirectional Forwarding
Detection (BFD) for multipoint networks to detect data plane failures
in Multiprotocol Label Switching (MPLS) point-to-multipoint (p2mp)
Label Switched Paths (LSPs). It also describes the applicability of
out-band solutions to bootstrap a BFD session in this environment.
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-
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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 April 15, 2019.
Copyright Notice
Copyright (c) 2018 IETF Trust and the persons identified as the
document authors. All rights reserved.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Conventions used in this document . . . . . . . . . . . . . . 2
2.1. Terminology . . . . . . . . . . . . . . . . . . . . . . . 2
2.2. Requirements Language . . . . . . . . . . . . . . . . . . 3
3. Multipoint BFD Encapsulation . . . . . . . . . . . . . . . . 3
3.1. IP Encapsulation of Multipoint BFD . . . . . . . . . . . 3
3.2. Non-IP Encapsulation of Multipoint BFD . . . . . . . . . 4
4. Bootstrapping Multipoint BFD . . . . . . . . . . . . . . . . 4
4.1. LSP Ping . . . . . . . . . . . . . . . . . . . . . . . . 4
4.2. Control Plane . . . . . . . . . . . . . . . . . . . . . . 4
5. Security Considerations . . . . . . . . . . . . . . . . . . . 4
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 4
6.1. Source MEP ID IP Address Type . . . . . . . . . . . . . . 4
7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 5
8. Normative References . . . . . . . . . . . . . . . . . . . . 5
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 6
1. Introduction
[I-D.ietf-bfd-multipoint] defines a method of using Bidirectional
Detection (BFD) [RFC5880] to monitor and detect unicast failures
between the sender (head) and one or more receivers (tails) in
multipoint or multicast networks. This document describes procedures
for using such mode of BFD protocol to detect data plane failures in
Multiprotocol Label Switching (MPLS) point-to-multipoint (p2mp) Label
Switched Paths (LSPs). The document also describes the applicability
of out-band solutions to bootstrap a BFD session in this environment.
2. Conventions used in this document
2.1. Terminology
MPLS: Multiprotocol Label Switching
LSP: Label Switched Path
BFD: Bidirectional Forwarding Detection
p2mp: Point-to-Multipoint
FEC: Forwarding Equivalence Class
G-ACh: Generic Associated Channel
ACH: Associated Channel Header
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GAL: G-ACh Label
2.2. 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 BCP
14 [RFC2119] [RFC8174] when, and only when, they appear in all
capitals, as shown here.
3. Multipoint BFD Encapsulation
[I-D.ietf-bfd-multipoint] defines how the tail of multipoint BFD
session demultiplexes received BFD control packet when Your
Discriminator is not set, i.e., equals zero. Because
[I-D.ietf-bfd-multipoint] uses BFD in Demand mode the head of BFD
multipoint session transmits BFD control packets with Your
Discriminator set to zero. As a result, a tail cannot demultiplex
BFD sessions using Your Discriminator, as defined in [RFC5880].
[I-D.ietf-bfd-multipoint] requires that in order to demultiplex BFD
sessions the tail uses the source IP address, My Discriminator and
the identity of the multipoint tree which the Multipoint BFD Control
packet was received from. The identity of the multipoint tree MAY be
provided by the p2mp MPLS LSP label in case of inclusive p-tree or
upstream assigned label in case of aggregate p-tree. The source IP
address MAY be drawn from the IP header if BFD control packet
transmitted by the head using IP/UDP encapsulation as described in
Section 3.1. Non-IP encapsulation case described in Section 3.2.
3.1. IP Encapsulation of Multipoint BFD
[I-D.ietf-bfd-multipoint] defines IP/UDP encapsulation for multipoint
BFD over p2mp MPLS LSP:
UDP destination port MUST be set to 3784;
destination IP address MUST be from the 127/8 range for IPv4 and
from the 0:0:0:0:0:FFFF:7F00/104 range for IPv6;
This specification further clarifies that:
if multiple alternative paths for the given p2mp LSP Forwarding
Equivalence Class(FEC) exist, the MultipointHead SHOULD use
Entropy Label [RFC6790] used for LSP Ping [RFC8029] to exercise
that particular alternative path;
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or the MultipointHead MAY use, as destination IP address, the IP
address discovered by LSP Ping traceroute [RFC8029] to exercise
that particular alternate path.
3.2. Non-IP Encapsulation of Multipoint BFD
Non-IP encapsulation for multipoint BFD over p2mp MPLS LSP MUST use
Generic Associated Channel (G-ACh) Label (GAL) [RFC5586] at the
bottom of the label stack followed by Associated Channel Header
(ACH). Channel Type field in ACH MUST be set to BFD CV [RFC6428].
To provide the identity of the MultipointHead for the particular
multipoint BFD session this document defines new Source MEP ID IP
Address type (TBA1) in Section 6.1. If the Length value is 4, then
the Value field contains an IPv4 address. If the Length value is 16,
then the Value field contains an IPv6 address. Any other value of
the Length field MUST be considered as an error, and the BFD control
packet MUST be discarded.
4. Bootstrapping Multipoint BFD
4.1. LSP Ping
MaultipointHead MAY use LSP Ping [RFC8029] using in Target FEC TLV,
as appropriate, sub-TLVs defined in Section 3.1 [RFC6425].
4.2. Control Plane
BGP-BFD Attribute [I-D.ietf-bess-mvpn-fast-failover] MAY be used to
bootstrap multipoint BFD session on a tail.
5. Security Considerations
This document does not introduce new security aspects but inherits
all security considerations from [RFC5880], [RFC5884], [RFC7726],
[I-D.ietf-bfd-multipoint], [RFC8029], and [RFC6425].
6. IANA Considerations
6.1. Source MEP ID IP Address Type
IANA is required to allocate value (TBD) for the Source MEP ID IP
Address type from the "CC/CV MEP-ID TLV" registry which is under the
"Pseudowire Associated Channel Types" registry.
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+-------+-------------+---------------+
| Value | Description | Reference |
+-------+-------------+---------------+
| TBA1 | IP Address | This document |
+-------+-------------+---------------+
Table 1: Source MEP ID IP Address TLV Type
7. Acknowledgements
TBD
8. Normative References
[I-D.ietf-bess-mvpn-fast-failover]
Morin, T., Kebler, R., and G. Mirsky, "Multicast VPN fast
upstream failover", draft-ietf-bess-mvpn-fast-failover-03
(work in progress), May 2018.
[I-D.ietf-bfd-multipoint]
Katz, D., Ward, D., Networks, J., and G. Mirsky, "BFD for
Multipoint Networks", draft-ietf-bfd-multipoint-18 (work
in progress), June 2018.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/info/rfc2119>.
[RFC5586] Bocci, M., Ed., Vigoureux, M., Ed., and S. Bryant, Ed.,
"MPLS Generic Associated Channel", RFC 5586,
DOI 10.17487/RFC5586, June 2009,
<https://www.rfc-editor.org/info/rfc5586>.
[RFC5880] Katz, D. and D. Ward, "Bidirectional Forwarding Detection
(BFD)", RFC 5880, DOI 10.17487/RFC5880, June 2010,
<https://www.rfc-editor.org/info/rfc5880>.
[RFC5884] Aggarwal, R., Kompella, K., Nadeau, T., and G. Swallow,
"Bidirectional Forwarding Detection (BFD) for MPLS Label
Switched Paths (LSPs)", RFC 5884, DOI 10.17487/RFC5884,
June 2010, <https://www.rfc-editor.org/info/rfc5884>.
[RFC6425] Saxena, S., Ed., Swallow, G., Ali, Z., Farrel, A.,
Yasukawa, S., and T. Nadeau, "Detecting Data-Plane
Failures in Point-to-Multipoint MPLS - Extensions to LSP
Ping", RFC 6425, DOI 10.17487/RFC6425, November 2011,
<https://www.rfc-editor.org/info/rfc6425>.
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[RFC6428] Allan, D., Ed., Swallow, G., Ed., and J. Drake, Ed.,
"Proactive Connectivity Verification, Continuity Check,
and Remote Defect Indication for the MPLS Transport
Profile", RFC 6428, DOI 10.17487/RFC6428, November 2011,
<https://www.rfc-editor.org/info/rfc6428>.
[RFC6790] Kompella, K., Drake, J., Amante, S., Henderickx, W., and
L. Yong, "The Use of Entropy Labels in MPLS Forwarding",
RFC 6790, DOI 10.17487/RFC6790, November 2012,
<https://www.rfc-editor.org/info/rfc6790>.
[RFC7726] Govindan, V., Rajaraman, K., Mirsky, G., Akiya, N., and S.
Aldrin, "Clarifying Procedures for Establishing BFD
Sessions for MPLS Label Switched Paths (LSPs)", RFC 7726,
DOI 10.17487/RFC7726, January 2016,
<https://www.rfc-editor.org/info/rfc7726>.
[RFC8029] Kompella, K., Swallow, G., Pignataro, C., Ed., Kumar, N.,
Aldrin, S., and M. Chen, "Detecting Multiprotocol Label
Switched (MPLS) Data-Plane Failures", RFC 8029,
DOI 10.17487/RFC8029, March 2017,
<https://www.rfc-editor.org/info/rfc8029>.
[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>.
Author's Address
Greg Mirsky
ZTE Corp.
Email: gregimirsky@gmail.com
Mirsky Expires April 15, 2019 [Page 6]
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