Bidirectional Forwarding Detection (BFD) for Multi-point Networks and Protocol Independent Multicast - Sparse Mode (PIM-SM) Use Case
draft-mirsky-pim-bfd-p2mp-use-case-01
This document is an Internet-Draft (I-D).
Anyone may submit an I-D to the IETF.
This I-D is not endorsed by the IETF and has no formal standing in the
IETF standards process.
The information below is for an old version of the document.
| Document | Type |
This is an older version of an Internet-Draft whose latest revision state is "Replaced".
|
|
|---|---|---|---|
| Authors | Greg Mirsky , Ji Xiaoli | ||
| Last updated | 2018-04-13 | ||
| Replaced by | draft-ietf-pim-bfd-p2mp-use-case, draft-ietf-pim-bfd-p2mp-use-case, draft-ietf-pim-bfd-p2mp-use-case, RFC 9186 | ||
| RFC stream | (None) | ||
| Formats | |||
| Stream | Stream state | (No stream defined) | |
| Consensus boilerplate | Unknown | ||
| RFC Editor Note | (None) | ||
| IESG | IESG state | I-D Exists | |
| Telechat date | (None) | ||
| Responsible AD | (None) | ||
| Send notices to | (None) |
draft-mirsky-pim-bfd-p2mp-use-case-01
PIM Working Group G. Mirsky
Internet-Draft ZTE Corp.
Updates: 7761 (if approved) J. Xiaoli
Intended status: Standards Track ZTE Corporation
Expires: October 15, 2018 April 13, 2018
Bidirectional Forwarding Detection (BFD) for Multi-point Networks and
Protocol Independent Multicast - Sparse Mode (PIM-SM) Use Case
draft-mirsky-pim-bfd-p2mp-use-case-01
Abstract
This document discusses the use of Bidirectional Forwarding Detection
(BFD) for multi-point networks to provide nodes that participate in
Protocol Independent Multicast - Sparse Mode (PIM-SM) over shared-
media segment with the sub-second convergence of the Designated
Router and defines the extension to bootstrap point-to-multipoint BFD
session. Optional extension to PIM-SM Hello, as defined in RFC 7761,
also defined in this document.
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 https://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 October 15, 2018.
Copyright Notice
Copyright (c) 2018 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
(https://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
Mirsky & Xiaoli Expires October 15, 2018 [Page 1]
Internet-Draft BFD P2MP Use in PIM-SM April 2018
to this document. Code Components extracted from this document must
include Simplified BSD License text as described in Section 4.e of
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 . . . . . . . . . . . . 3
1.1.1. Terminology . . . . . . . . . . . . . . . . . . . . . 3
1.1.2. Requirements Language . . . . . . . . . . . . . . . . 3
2. Problem Statement . . . . . . . . . . . . . . . . . . . . . . 3
3. Applicability of p2mp BFD . . . . . . . . . . . . . . . . . . 3
3.1. Multipoint BFD Encapsulation . . . . . . . . . . . . . . 4
4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 5
5. Security Considerations . . . . . . . . . . . . . . . . . . . 5
6. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 5
7. Normative References . . . . . . . . . . . . . . . . . . . . 5
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 6
1. Introduction
[RFC7761] is the current specification of the Protocol Independent
Multicast - Sparse Mode (PIM-SM) for IPv4 and IPv6 networks.
Confirming implementation of PIM-SM elects a Designated Router (DR)
on each PIM-SM interface. When a group of PIM-SM nodes is connected
to shared-media segment, e.g. Ethernet, the one elected as DR is to
act on behalf of directly connected hosts in context of the PIM-SM
protocol. Failure of the DR impacts the quality of the multicast
services it provides to directly connected hosts because the default
failure detection interval for PIM-SM routers is 105 seconds.
Introduction of Backup DR (BDR), proposed in
[I-D.ietf-pim-dr-improvement] improves convergence time in the PIM-SM
over shared-media segment but still depends on long failure detection
interval.
Bidirectional Forwarding Detection (BFD) [RFC5880] had been
originally defined to detect failure of point-to-point (p2p) paths -
single-hop [RFC5881], multihop [RFC5883]. [I-D.ietf-bfd-multipoint]
extends [RFC5880] for multipoint and multicast networks, which
precisely characterizes deployment scenarios for PIM-SM over LAN
segment. This document demonstrates how point-to-multipoint (p2mp)
BFD can enable faster detection of PIM-SM DR and BDR failure and thus
minimize multicast service disruption. The document also defines the
extension to PIM-SM [RFC7761] to bootstrap a PIM-SM router to join in
p2mp BFD session over shared-media link.
Mirsky & Xiaoli Expires October 15, 2018 [Page 2]
Internet-Draft BFD P2MP Use in PIM-SM April 2018
1.1. Conventions used in this document
1.1.1. Terminology
BFD: Bidirectional Forwarding Detection
BDR: Backup Designated Router
DR: Designated Router
p2mp: Pont-to-Multipoint
PIM-SM: Protocol Independent Multicast - Sparse Mode
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 BCP
14 [RFC2119] [RFC8174] when, and only when, they appear in all
capitals, as shown here.
2. Problem Statement
Several PIM-SM routers may be connected over shared-media link, e.g.
Ethernet. [RFC7761] does not provide a method for fast, e.g. sub-
second, DR failure detection by other PIM-SM routers on the same
Ethernet link. BFD already has many implementations based on HW that
are capable to support multiple sub-second session concurrently.
[Editor's note: monitoring of PIM-SM BDR liveliness will be addressed
in the next update of the draft.]
3. Applicability of p2mp BFD
[I-D.ietf-bfd-multipoint] may provide the efficient and scalable
solution for the fast-converging environment that has head-tails
relationships. Each such group presents itself as p2mp BFD session
with its head being the root and other routers being tails of the
p2mp BFD session. Figure 1 displays the new BFD Discriminator TLV
[RFC7761] to bootstrap tail of the p2mp BFD session.
Mirsky & Xiaoli Expires October 15, 2018 [Page 3]
Internet-Draft BFD P2MP Use in PIM-SM April 2018
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| OptionType | OptionLength |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| My Discriminator |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 1: BFD Discriminator TLV to Bootstrap P2MP BFD session
where new fields are interpreted as:
OptionType is a value (TBA1) assigned by IANA Section 4 that
identifies the TLV as BFD Discriminator TLV;
OptionLength value is always 4
My Discriminator - My Discriminator value allocated by the root of
the p2mp BFD session.
If PIM-SM routers, that support this specification, are configured to
use p2mp BFD for faster convergence, then the DR MUST create BFD
session MultipointHead, as defined in [I-D.ietf-bfd-multipoint].
PIM-SM DR MUST include BFD TLV in its PIM-Hello message. PIM-SM DR
periodically transmits BFD control packets. Source IP address of the
BFD control packet MUST be the same as the source IP address of the
PIM-Hello with BFD TLV messages being transmitted by the DR. The
values of My Discriminator in the BFD control packet and My
Discriminator field of the BFD TLV in PIM-Hello, transmitted by the
PIM-SM DR MUST be the same. When non-DR PIM-SM router receives PIM-
Hello packet from DR with BFD TLV it MAY create p2mp BFD session as
MultipointTail, as defined in [I-D.ietf-bfd-multipoint], and
demultiplex p2mp BFD test session based on DR source IP address the
My Discriminator value it learned from BFD Discriminator TLV. If DR
ceased to include BFD TLV in its PIM-Hello message, other PIM-SM
nodes MUST close corresponding MultipointTail BFD session.
3.1. Multipoint BFD Encapsulation
The MultipointHead of p2mp BFD session when transmitting BFD control
packet:
MUST set TTL value to 1;
SHOULD use group address ALL-PIM-ROUTERS ('224.0.0.13' for IPv4
and 'ff02::d' for IPv6) as destination IP address
Mirsky & Xiaoli Expires October 15, 2018 [Page 4]
Internet-Draft BFD P2MP Use in PIM-SM April 2018
MAY use network broadcast address for IPv4 or link-local all nodes
multicast group for IPv6 as the destination IP address;
MUST set destination UDP port value to 3784 when transmitting BFD
control packets, as defined in [I-D.ietf-bfd-multipoint].
4. IANA Considerations
IANA is requested to allocate a new OptionType value from PIM Hello
Options registry according to:
+-------------+----------------+-------------------+---------------+
| Value Name | Length Number | Name Protocol | Reference |
+-------------+----------------+-------------------+---------------+
| TBA | 4 | BFD Discriminator | This document |
+-------------+----------------+-------------------+---------------+
Table 1: BFD Discriminator option type
5. Security Considerations
Security considerations discussed in [RFC7761], [RFC5880], and
[I-D.ietf-bfd-multipoint], apply to this document.
6. Acknowledgments
TBD
7. Normative References
[I-D.ietf-bfd-multipoint]
Katz, D., Ward, D., Networks, J., and G. Mirsky, "BFD for
Multipoint Networks", draft-ietf-bfd-multipoint-14 (work
in progress), February 2018.
[I-D.ietf-pim-dr-improvement]
Zhang, Z., hu, f., Xu, B., and m. mishra, "PIM DR
Improvement", draft-ietf-pim-dr-improvement-04 (work in
progress), December 2017.
[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>.
[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>.
Mirsky & Xiaoli Expires October 15, 2018 [Page 5]
Internet-Draft BFD P2MP Use in PIM-SM April 2018
[RFC5881] Katz, D. and D. Ward, "Bidirectional Forwarding Detection
(BFD) for IPv4 and IPv6 (Single Hop)", RFC 5881,
DOI 10.17487/RFC5881, June 2010,
<https://www.rfc-editor.org/info/rfc5881>.
[RFC5883] Katz, D. and D. Ward, "Bidirectional Forwarding Detection
(BFD) for Multihop Paths", RFC 5883, DOI 10.17487/RFC5883,
June 2010, <https://www.rfc-editor.org/info/rfc5883>.
[RFC7761] Fenner, B., Handley, M., Holbrook, H., Kouvelas, I.,
Parekh, R., Zhang, Z., and L. Zheng, "Protocol Independent
Multicast - Sparse Mode (PIM-SM): Protocol Specification
(Revised)", STD 83, RFC 7761, DOI 10.17487/RFC7761, March
2016, <https://www.rfc-editor.org/info/rfc7761>.
[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>.
Authors' Addresses
Greg Mirsky
ZTE Corp.
Email: gregimirsky@gmail.com
Ji Xiaoli
ZTE Corporation
No.50 Software Avenue, Yuhuatai District
Nanjing
China
Email: ji.xiaoli@zte.com.cn
Mirsky & Xiaoli Expires October 15, 2018 [Page 6]