draft-ietf-pim-bfd-p2mp-use-case-02.txt   draft-ietf-pim-bfd-p2mp-use-case-03.txt 
PIM Working Group G. Mirsky PIM Working Group G. Mirsky
Internet-Draft ZTE Corp. Internet-Draft ZTE Corp.
Intended status: Standards Track J. Xiaoli Intended status: Standards Track J. Xiaoli
Expires: January 26, 2020 ZTE Corporation Expires: July 25, 2020 ZTE Corporation
July 25, 2019 January 22, 2020
Bidirectional Forwarding Detection (BFD) for Multi-point Networks and Bidirectional Forwarding Detection (BFD) for Multi-point Networks and
Protocol Independent Multicast - Sparse Mode (PIM-SM) Use Case Protocol Independent Multicast - Sparse Mode (PIM-SM) Use Case
draft-ietf-pim-bfd-p2mp-use-case-02 draft-ietf-pim-bfd-p2mp-use-case-03
Abstract Abstract
This document discusses the use of Bidirectional Forwarding Detection This document discusses the use of Bidirectional Forwarding Detection
(BFD) for multi-point networks to provide nodes that participate in (BFD) for multi-point networks to provide nodes that participate in
Protocol Independent Multicast - Sparse Mode (PIM-SM) with the sub- Protocol Independent Multicast - Sparse Mode (PIM-SM) with the sub-
second convergence. Optional extension to PIM-SM Hello, as specified second convergence. Optional extension to PIM-SM Hello, as specified
in RFC 7761, to bootstrap point-to-multipoint BFD session. also in RFC 7761, to bootstrap point-to-multipoint BFD session. also
defined in this document. defined in this document.
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Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
1.1. Conventions used in this document . . . . . . . . . . . . 3 1.1. Conventions used in this document . . . . . . . . . . . . 3
1.1.1. Terminology . . . . . . . . . . . . . . . . . . . . . 3 1.1.1. Terminology . . . . . . . . . . . . . . . . . . . . . 3
1.1.2. Requirements Language . . . . . . . . . . . . . . . . 3 1.1.2. Requirements Language . . . . . . . . . . . . . . . . 3
2. Problem Statement . . . . . . . . . . . . . . . . . . . . . . 3 2. Problem Statement . . . . . . . . . . . . . . . . . . . . . . 3
3. Applicability of p2mp BFD . . . . . . . . . . . . . . . . . . 3 3. Applicability of p2mp BFD . . . . . . . . . . . . . . . . . . 4
3.1. Multipoint BFD Encapsulation . . . . . . . . . . . . . . 5 3.1. Using P2MP BFD in PIM DR/BDR Monitoring . . . . . . . . . 4
4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 5 3.2. P2MP BFD in PIM DR Load Balancing . . . . . . . . . . . . 5
3.3. Multipoint BFD Encapsulation . . . . . . . . . . . . . . 6
4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 6
5. Security Considerations . . . . . . . . . . . . . . . . . . . 6 5. Security Considerations . . . . . . . . . . . . . . . . . . . 6
6. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 6 6. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 6
7. Normative References . . . . . . . . . . . . . . . . . . . . 6 7. References . . . . . . . . . . . . . . . . . . . . . . . . . 7
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 7 7.1. Normative References . . . . . . . . . . . . . . . . . . 7
7.2. Informative References . . . . . . . . . . . . . . . . . 8
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 8
1. Introduction 1. Introduction
Faster convergence in the control plane, in general, is beneficial Faster convergence in the control plane, in general, is beneficial
and allows minimizing periods of traffic blackholing, transient and allows minimizing periods of traffic blackholing, transient
routing loops, and other scenarios that may negatively affect service routing loops, and other scenarios that may negatively affect service
data flow. That equally applies to unicast and multicast routing data flow. That equally applies to unicast and multicast routing
protocols. protocols.
[RFC7761] is the current specification of the Protocol Independent [RFC7761] is the current specification of the Protocol Independent
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1.1. Conventions used in this document 1.1. Conventions used in this document
1.1.1. Terminology 1.1.1. Terminology
BFD: Bidirectional Forwarding Detection BFD: Bidirectional Forwarding Detection
BDR: Backup Designated Router BDR: Backup Designated Router
DR: Designated Router DR: Designated Router
DRLB: Designated Router Load Balancing
DRLB-Cap: DRLB Capability Hello Option
DRLB-List: DRLB List Hello Option
GDR: Group Designated Router
p2mp: Pont-to-Multipoint p2mp: Pont-to-Multipoint
PIM-SM: Protocol Independent Multicast - Sparse Mode PIM-SM: Protocol Independent Multicast - Sparse Mode
1.1.2. Requirements Language 1.1.2. Requirements Language
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in BCP "OPTIONAL" in this document are to be interpreted as described in BCP
14 [RFC2119] [RFC8174] when, and only when, they appear in all 14 [RFC2119] [RFC8174] when, and only when, they appear in all
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implementations based on HW that are capable of supporting multiple implementations based on HW that are capable of supporting multiple
sub-second sessions concurrently. sub-second sessions concurrently.
3. Applicability of p2mp BFD 3. Applicability of p2mp BFD
[RFC8562] may provide an efficient and scalable solution for the [RFC8562] may provide an efficient and scalable solution for the
fast-converging environment that demonstrates the head-tails fast-converging environment that demonstrates the head-tails
relationship. Each such group presents itself as p2mp BFD session relationship. Each such group presents itself as p2mp BFD session
with its head being the root and other routers being tails of the with its head being the root and other routers being tails of the
p2mp BFD session. Figure 1 displays the new optional BFD p2mp BFD session. Figure 1 displays the new optional BFD
Discriminator TLV to bootstrap tail of the p2mp BFD session. Discriminator PIM Hello Option to bootstrap tail of the p2mp BFD
session.
0 1 2 3 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 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 | | OptionType | OptionLength |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| My Discriminator | | My Discriminator |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 1: BFD Discriminator TLV to Bootstrap P2MP BFD session Figure 1: BFD Discriminator PIM Hello Option
where new fields are interpreted as: where new fields are interpreted as:
OptionType is a value (TBA1) assigned by IANA Section 4 that OptionType is a value (TBA1) assigned by IANA Section 4 that
identifies the TLV as BFD Discriminator TLV; identifies the TLV as BFD Discriminator TLV;
OptionLength value is always 4 OptionLength value is always 4
My Discriminator - My Discriminator value allocated by the root of My Discriminator - My Discriminator value allocated by the root of
the p2mp BFD session. the p2mp BFD session.
3.1. Using P2MP BFD in PIM DR/BDR Monitoring
If PIM-SM routers that support this specification are configured to If PIM-SM routers that support this specification are configured to
use p2mp BFD for faster convergence, then the router to be monitored, use p2mp BFD for faster convergence, then the router to be monitored,
referred to as 'head', MUST create BFD session of type referred to as 'head', MUST create BFD session of type
MultipointHead, as defined in [RFC8562]. If the head doesn't support MultipointHead, as defined in [RFC8562]. If the head doesn't support
[I-D.ietf-pim-dr-improvement], but, for example, uses procedures [I-D.ietf-pim-dr-improvement], but, for example, uses procedures
defined in [I-D.mankamana-pim-bdr], then it MUST include BFD TLV in defined in [I-D.mankamana-pim-bdr], then it MUST include BFD TLV in
its PIM-Hello message. If the head uses extensions defined in its PIM-Hello message. If the head uses extensions defined in
[I-D.ietf-pim-dr-improvement], then DR MUST include BFD TLV in its [I-D.ietf-pim-dr-improvement], then DR MUST include BFD TLV in its
Hello message. The DR Address TLV also MUST be included in the Hello Hello message. The DR Address TLV also MUST be included in the Hello
message. For a BDR it is RECOMMENDED to include BFD TLV in its Hello message. For a BDR it is RECOMMENDED to include BFD TLV in its Hello
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the tail has detected MultipointHead failure, it MUST remove the the tail has detected MultipointHead failure, it MUST remove the
neighbor. If the failed head node was PIM-SM DR or BDR, the tail MAY neighbor. If the failed head node was PIM-SM DR or BDR, the tail MAY
start DR Election process as specified in Section 4.3.2 [RFC7761] or start DR Election process as specified in Section 4.3.2 [RFC7761] or
Section 4.1 [I-D.ietf-pim-dr-improvement] respectively. Section 4.1 [I-D.ietf-pim-dr-improvement] respectively.
If the head ceased to include BFD TLV in its PIM-Hello message, tails If the head ceased to include BFD TLV in its PIM-Hello message, tails
MUST close the corresponding MultipointTail BFD session. Thus the MUST close the corresponding MultipointTail BFD session. Thus the
tail stops using BFD to monitor the head and reverts to the tail stops using BFD to monitor the head and reverts to the
procedures defined in [RFC7761] and [I-D.ietf-pim-dr-improvement]. procedures defined in [RFC7761] and [I-D.ietf-pim-dr-improvement].
3.1. Multipoint BFD Encapsulation 3.2. P2MP BFD in PIM DR Load Balancing
[I-D.ietf-pim-drlb] defined the modification, Designated Router Load
Balancing (DRLB), to the PIM-SM protocol that allows for distribution
of PIM-SM DR responsibilities on a multi-access network segment.
[I-D.ietf-pim-drlb] introduced the new PIM Hello options - Load
Balancing Capability (DRLB-Cap) and DR Load Balancing List (DRLB-
List). PIM router that includes DRLB-Cap Hello Option MAY include
BFD Discriminator PIM Hello Option (Figure 1). That router MUST
create a BFD session and set itself as MultipointHead [RFC8562]. The
router MUST set bfd.SessionState in the MultipointHead session to
Down. If a PIM router that includes BFD Discriminator Option in its
Hello finds its address in DRLB-List PIM Hello Option as Group
Designated Router (GDR) Candidate for the first time, the router MUST
set bfd.SessionState to Up and start periodically transmit BFD
control messages. If the PIM router that was GDR Candidate doesn't
find its address in the most recent DRLB-List Option, the router MUST
set bfd.SessionState to Down and cease transmitting BFD control
messages. For each GDR Candidate that includes BFD Discriminator
Option in its PIM Hello, PIM DR creates a MultipointTail session
[RFC8562]. PIM DR demultiplexes BFD sessions based on the value in
My Discriminator field and the source IP address. If PIM DR detects
a failure of one of the sessions, it MUST remove that router from the
GDR Candidate list and immediately transmit a new DRLB-List Option.
3.3. Multipoint BFD Encapsulation
The MultipointHead of p2mp BFD session when transmitting BFD control The MultipointHead of p2mp BFD session when transmitting BFD control
packet: packet:
MUST set TTL value to 1; MUST set TTL value to 1;
SHOULD use group address ALL-PIM-ROUTERS ('224.0.0.13' for IPv4 SHOULD use group address ALL-PIM-ROUTERS ('224.0.0.13' for IPv4
and 'ff02::d' for IPv6) as destination IP address and 'ff02::d' for IPv6) as destination IP address
MAY use network broadcast address for IPv4 or link-local all nodes MAY use network broadcast address for IPv4 or link-local all nodes
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An implementation that supports this specification SHOULD use a An implementation that supports this specification SHOULD use a
mechanism to control the maximum number of BFD sessions that can be mechanism to control the maximum number of BFD sessions that can be
active at the same time. active at the same time.
6. Acknowledgments 6. Acknowledgments
Authors cannot say enough to express their appreciation of comments Authors cannot say enough to express their appreciation of comments
and suggestions we received from Stig Venaas. and suggestions we received from Stig Venaas.
7. Normative References 7. References
7.1. Normative References
[I-D.ietf-pim-dr-improvement] [I-D.ietf-pim-dr-improvement]
Zhang, Z., hu, f., Xu, B., and m. mishra, "PIM DR Zhang, Z., hu, f., Xu, B., and m. mishra, "PIM DR
Improvement", draft-ietf-pim-dr-improvement-07 (work in Improvement", draft-ietf-pim-dr-improvement-09 (work in
progress), January 2019. progress), October 2019.
[I-D.mankamana-pim-bdr] [I-D.ietf-pim-drlb]
mishra, m., "PIM Backup Designated Router Procedure", Cai, Y., Ou, H., Vallepalli, S., mishra, m., Venaas, S.,
draft-mankamana-pim-bdr-02 (work in progress), April 2019. and A. Green, "PIM Designated Router Load Balancing",
draft-ietf-pim-drlb-15 (work in progress), January 2020.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997, DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/info/rfc2119>. <https://www.rfc-editor.org/info/rfc2119>.
[RFC5880] Katz, D. and D. Ward, "Bidirectional Forwarding Detection [RFC5880] Katz, D. and D. Ward, "Bidirectional Forwarding Detection
(BFD)", RFC 5880, DOI 10.17487/RFC5880, June 2010, (BFD)", RFC 5880, DOI 10.17487/RFC5880, June 2010,
<https://www.rfc-editor.org/info/rfc5880>. <https://www.rfc-editor.org/info/rfc5880>.
skipping to change at page 7, line 14 skipping to change at page 8, line 5
[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
May 2017, <https://www.rfc-editor.org/info/rfc8174>. May 2017, <https://www.rfc-editor.org/info/rfc8174>.
[RFC8562] Katz, D., Ward, D., Pallagatti, S., Ed., and G. Mirsky, [RFC8562] Katz, D., Ward, D., Pallagatti, S., Ed., and G. Mirsky,
Ed., "Bidirectional Forwarding Detection (BFD) for Ed., "Bidirectional Forwarding Detection (BFD) for
Multipoint Networks", RFC 8562, DOI 10.17487/RFC8562, Multipoint Networks", RFC 8562, DOI 10.17487/RFC8562,
April 2019, <https://www.rfc-editor.org/info/rfc8562>. April 2019, <https://www.rfc-editor.org/info/rfc8562>.
7.2. Informative References
[I-D.mankamana-pim-bdr]
mishra, m., Goh, J., and G. Mishra, "PIM Backup Designated
Router Procedure", draft-mankamana-pim-bdr-03 (work in
progress), October 2019.
Authors' Addresses Authors' Addresses
Greg Mirsky Greg Mirsky
ZTE Corp. ZTE Corp.
Email: gregimirsky@gmail.com Email: gregimirsky@gmail.com
Ji Xiaoli Ji Xiaoli
ZTE Corporation ZTE Corporation
No.50 Software Avenue, Yuhuatai District No.50 Software Avenue, Yuhuatai District
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