BIER WG Quan Xiong
Internet-Draft Greg Mirsky
Intended status: Standards Track Fangwei Hu
Expires: September 2, 2019 ZTE Corporation
Chang Liu
China Unicom
March 1, 2019
BIER BFD
draft-hu-bier-bfd-03.txt
Abstract
Point to multipoint (P2MP) BFD is designed to verify multipoint
connectivity. This document specifies the application of P2MP BFD in
BIER network.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Conventions used in this document . . . . . . . . . . . . . . 3
2.1. Terminology . . . . . . . . . . . . . . . . . . . . . . . 3
2.2. Requirements Language . . . . . . . . . . . . . . . . . . 3
3. BIER BFD Encapsulation . . . . . . . . . . . . . . . . . . . 3
4. Bootstrapping BIER BFD . . . . . . . . . . . . . . . . . . . 3
4.1. BIER OAM Ping Bootstrap . . . . . . . . . . . . . . . . . 3
4.2. IGP protocol Bootstrap . . . . . . . . . . . . . . . . . 4
4.2.1. IS-IS extension for BIER BFD . . . . . . . . . . . . 4
4.2.2. OSPF extension for BIER BFD . . . . . . . . . . . . . 5
5. Discriminators and Packet Demultiplexing . . . . . . . . . . 5
6. Active Tail in BIER BFD . . . . . . . . . . . . . . . . . . . 5
7. Security Considerations . . . . . . . . . . . . . . . . . . . 6
8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 6
9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 6
10. References . . . . . . . . . . . . . . . . . . . . . . . . . 6
10.1. Normative References . . . . . . . . . . . . . . . . . . 6
10.2. Informative References . . . . . . . . . . . . . . . . . 7
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 8
1. Introduction
Bit Index Explicit Replication (BIER) [RFC8279] provides optimal
forwarding of multicast data packets through a multicast domain. It
does so without requiring any explicit tree-building protocol and
without requiring intermediate nodes to maintain any per-flow state.
BIER resilience use cases are described in
[I-D.xiong-bier-resilience] including End-to-End 1+1 and 1:1
Protection and the failure detection mechanisms MAY use P2MP BFD and
P2MP active tail detection method respectively.
[I-D.ietf-bfd-multipoint] defines a method of using Bidirectional
Forwarding Detection(BFD) to monitor and detect unicast failures
between the sender (head) and one or more receivers (tails) in
multipoint or multicast networks.
[I-D.ietf-bfd-multipoint-active-tail] describes active tail
extensions to the BFD protocol for multipoint networks.
This document describes the procedures for using such mode of BFD
protocol to verify multipoint or multicast connectivity between a
multipoint sender (the "head", Bit-Forwarding Ingress Routers(BFIRs))
and a set of one or more multipoint receivers (the"tails", Bit-
Forwarding Egress Routers(BFERs)). The BIER BFD only supports the
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unidirectional multicast. This document defines the use of P2MP BFD
as per [I-D.ietf-bfd-multipoint], and active tail as per
[I-D.ietf-bfd-multipoint-active-tail] for BIER-specific domain.
2. Conventions used in this document
2.1. Terminology
This document uses the acronyms defined in [RFC8279] along with the
following:
BFD: Bidirectional Forwarding Detection.
OAM: Operations, Administration, and Maintenance.
P2MP: Point to Multi-Point.
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. BIER BFD Encapsulation
BIER BFD encapsulation uses the BIER OAM packet format defined in
[I-D.ietf-bier-ping]. The value of the Msg Type field MUST be set to
BIER BFD (TBD1 by IANA ). BFD Control packet, defined in Section 4
[RFC5880] immediately follows the BIER OAM header.
4. Bootstrapping BIER BFD
4.1. BIER OAM Ping Bootstrap
The BIER OAM ping could be used for BIER BFD bootstrap. The BFIR
sends the BIER OAM ping Echo request messages carring a BFD
discriminator TLV which immediately follows the Target SI-Bitstring
TLV (section 3.3.2 [I-D.ietf-bier-ping]) which MUST be included to
carry the set of BFER information (Sub-domain-id, Set ID, BS Len,
Bitstring) for the purpose of session establishment.
The BFD discriminator TLV is a new TLV for BIER OAM TLV with the type
(TBD2 by IANA) and the length of 4. The value contains the 4-byte
local discriminator generated by BFIR for this session.
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4.2. IGP protocol Bootstrap
An alternative option to bootstrap the BIER BFD is to advertise the
BFD information IGP protocol in control plane. This document defines
a new BIER BFD Sub-TLV carried in IS-IS and OSPF capaibility to
advertise My Discriminator for BFIR.
4.2.1. IS-IS extension for BIER BFD
The new BIER BFD Sub-TLV is carried in the ISIS router capaiblity
TLV. The format is as follows.
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| My Discriminator |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| RESERVED | BIFT-id |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| BitString (first 32 bits) ~
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
~ ~
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
~ BitString (last 32 bits) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 1: BIER BFD Sub-TLV for IS-IS extension
Type : TBD3 by IANA.
Length : Length of the BIER BFD Sub-TLV for IS-IS extension, in
bytes.
My Discriminator : A unique, nonzero discriminator value generated by
BFIR for each multipoint path.
The BitString field carries the set of BFR-IDs of BFER(s) that the
BFIR expects to establish BIER BFD session.
The BIFT-id represents a particular Bit Index Forwarding Table (BIFT)
as per [RFC8279].
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4.2.2. OSPF extension for BIER BFD
The new BIER BFD Sub-TLV is carried in the Router Information Link
State Advertisement (LSA). The format is as follows.
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| My Discriminator |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| RESERVED | BIFT-id |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| BitString (first 32 bits) ~
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
~ ~
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
~ BitString (last 32 bits) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 2: BIER BFD Sub-TLV for OSPF extension
Type : TBD4 by IANA.
Length : Length of the BIER BFD Sub-TLV for OSPF extension, in bytes.
Other fields in BIER BFD Sub-TLV is the same with section 4.2.1.
5. Discriminators and Packet Demultiplexing
The tail(BFER) demultiplexes incoming BFD packets based on a
combination of the source address and My discriminator as specified
in [I-D.ietf-bfd-multipoint]. The source address is BFIR-id and BIER
MPLS Label (MPLS network) or BFIR-id and BIFT-id (Non-MPLS network)
for BIER BFD.
6. Active Tail in BIER BFD
[I-D.ietf-bfd-multipoint-active-tail] defined an extension for
Multipoint BFD, which allows tails to notify the head of the lack of
multipoint connectivity. For BIER BFD in active tail mode, the BFIR
may learn the state and connectivity of the BFERs. As per
[I-D.ietf-bfd-multipoint-active-tail], the BFIR can send the Poll
sequence messages in combination with the unicast BFD over the
monitored BFERs.
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7. Security Considerations
For BIER OAM packet procssing security considerations, see
[I-D.ietf-bier-ping].
For general multipoint BFD security considerations, see
[I-D.ietf-bfd-multipoint].
No additional security issues are raised in this document beyond
those that exist in the referenced BFD documents.
8. Acknowledgements
Authors would like to thank the comments and suggestions from Jeffrey
(Zhaohui) Zhang, Donald Eastlake 3rd.
9. IANA Considerations
IANA is requested to assign new type from the BIER OAM Message Type
registry as follows:
+--------+-----------------------------+------------------+
| Value | Description | Reference |
+--------+-----------------------------+------------------+
| TBD1 | BIER BFD | [this document] |
| TBD2 | BFD discriminator TLV | [this document] |
| TBD3 | BIER BFD Sub-TLV for IS-IS | [this document] |
| TBD4 | BIER BFD Sub-TLV for OSPF | [this document] |
+--------+-----------------------------+------------------+
Table 1
10. References
10.1. Normative References
[I-D.ietf-bfd-multipoint]
Katz, D., Ward, D., Networks, J., and G. Mirsky, "BFD for
Multipoint Networks", draft-ietf-bfd-multipoint-19 (work
in progress), December 2018.
[I-D.ietf-bier-ping]
Kumar, N., Pignataro, C., Akiya, N., Zheng, L., Chen, M.,
and G. Mirsky, "BIER Ping and Trace", draft-ietf-bier-
ping-04 (work in progress), October 2018.
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[I-D.xiong-bier-resilience]
Xiong, Q., hu, f., and G. Mirsky, "The Resilience for
BIER", draft-xiong-bier-resilience-01 (work in progress),
October 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>.
[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>.
[RFC6213] Hopps, C. and L. Ginsberg, "IS-IS BFD-Enabled TLV",
RFC 6213, DOI 10.17487/RFC6213, April 2011,
<https://www.rfc-editor.org/info/rfc6213>.
[RFC6328] Eastlake 3rd, D., "IANA Considerations for Network Layer
Protocol Identifiers", BCP 164, RFC 6328,
DOI 10.17487/RFC6328, July 2011,
<https://www.rfc-editor.org/info/rfc6328>.
[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>.
[RFC8279] Wijnands, IJ., Ed., Rosen, E., Ed., Dolganow, A.,
Przygienda, T., and S. Aldrin, "Multicast Using Bit Index
Explicit Replication (BIER)", RFC 8279,
DOI 10.17487/RFC8279, November 2017,
<https://www.rfc-editor.org/info/rfc8279>.
10.2. Informative References
[I-D.ietf-bfd-multipoint-active-tail]
Katz, D., Ward, D., Networks, J., and G. Mirsky, "BFD
Multipoint Active Tails.", draft-ietf-bfd-multipoint-
active-tail-10 (work in progress), November 2018.
[ISO9577] ISO/IEC TR 9577:1999,, "International Organization for
Standardization "Information technology -
Telecommunications and Information exchange between
systems - Protocol identification in the network layer"",
1999.
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Authors' Addresses
Quan Xiong
ZTE Corporation
No.6 Huashi Park Rd
Wuhan, Hubei 430223
China
Phone: +86 27 83531060
Email: xiong.quan@zte.com.cn
Greg Mirsky
ZTE Corporation
USA
Email: gregimirsky@gmail.com
Fangwei Hu
ZTE Corporation
No.889 Bibo Rd
Shanghai 201203
China
Phone: +86 21 68896273
Email: hu.fangwei@zte.com.cn
Chang Liu
China Unicom
No.9 Shouti Nanlu
Beijing 100048
China
Phone: +86-010-68799999-7294
Email: liuc131@chinaunicom.cn
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