< draft-ietf-pim-bfd-p2mp-use-case-00.txt   draft-ietf-pim-bfd-p2mp-use-case-01.txt >
PIM Working Group G. Mirsky PIM Working Group G. Mirsky
Internet-Draft ZTE Corp. Internet-Draft ZTE Corp.
Updates: 7761 (if approved) J. Xiaoli Updates: 7761 (if approved) J. Xiaoli
Intended status: Standards Track ZTE Corporation Intended status: Standards Track ZTE Corporation
Expires: April 25, 2019 October 22, 2018 Expires: December 19, 2019 June 17, 2019
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-00 draft-ietf-pim-bfd-p2mp-use-case-01
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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Copyright Notice Copyright Notice
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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 . . . . . . . . . . . . . . . . . . 3
3.1. Multipoint BFD Encapsulation . . . . . . . . . . . . . . 4 3.1. Multipoint BFD Encapsulation . . . . . . . . . . . . . . 5
4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 5 4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 5
5. Security Considerations . . . . . . . . . . . . . . . . . . . 5 5. Security Considerations . . . . . . . . . . . . . . . . . . . 5
6. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 5 6. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 6
7. Normative References . . . . . . . . . . . . . . . . . . . . 5 7. Normative References . . . . . . . . . . . . . . . . . . . . 6
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 6 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 7
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
Multicast - Sparse Mode (PIM-SM) for IPv4 and IPv6 networks. Multicast - Sparse Mode (PIM-SM) for IPv4 and IPv6 networks.
Confirming implementation of PIM-SM elects a Designated Router (DR) Confirming implementation of PIM-SM elects a Designated Router (DR)
on each PIM-SM interface. When a group of PIM-SM nodes is connected 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 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 act on behalf of directly connected hosts in the context of the PIM-
protocol. Failure of the DR impacts the quality of the multicast SM protocol. Failure of the DR impacts the quality of the multicast
services it provides to directly connected hosts because the default services it provides to directly connected hosts because the default
failure detection interval for PIM-SM routers is 105 seconds. failure detection interval for PIM-SM routers is 105 seconds.
Introduction of Backup DR (BDR), proposed in Introduction of Backup DR (BDR), proposed in
[I-D.ietf-pim-dr-improvement] improves convergence time in the PIM-SM [I-D.ietf-pim-dr-improvement], improves convergence time in the PIM-
over shared-media segment but still depends on long failure detection SM over shared-media segment but still depends on long failure
interval. detection interval.
Bidirectional Forwarding Detection (BFD) [RFC5880] had been Bidirectional Forwarding Detection (BFD) [RFC5880] had been
originally defined to detect failure of point-to-point (p2p) paths - originally defined to detect failure of point-to-point (p2p) paths -
single-hop [RFC5881], multihop [RFC5883]. [I-D.ietf-bfd-multipoint] single-hop [RFC5881], multihop [RFC5883]. [RFC8562] extends the BFD
extends the BFD base specification [RFC5880] for multipoint and base specification [RFC5880] for multipoint and multicast networks,
multicast networks, which precisely characterizes deployment which precisely characterizes deployment scenarios for PIM-SM over
scenarios for PIM-SM over LAN segment. This document demonstrates LAN segment. This document demonstrates how point-to-multipoint
how point-to-multipoint (p2mp) BFD can enable faster detection of (p2mp) BFD can enable faster detection of PIM-SM router failure and
PIM-SM router ailure and thus minimize multicast service disruption. thus minimize multicast service disruption. The document also
The document also defines the extension to PIM-SM [RFC7761] to defines the extension to PIM-SM [RFC7761] and
bootstrap a PIM-SM router to join in p2mp BFD session over shared- [I-D.ietf-pim-dr-improvement] to bootstrap a PIM-SM router to join in
media link. p2mp BFD session over shared-media link.
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
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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
capitals, as shown here. capitals, as shown here.
2. Problem Statement 2. Problem Statement
[RFC7761] does not provide a method for fast, e.g. sub-second, [RFC7761] does not provide a method for fast, e.g., sub-second,
failure detection of a neighbor PIM-SM router. BFD already has many failure detection of a neighbor PIM-SM router. BFD already has many
implementations based on HW that are capable to support multiple sub- implementations based on HW that are capable of supporting multiple
second session concurrently. sub-second sessions concurrently.
3. Applicability of p2mp BFD 3. Applicability of p2mp BFD
[I-D.ietf-bfd-multipoint] may provide the efficient and scalable [RFC8562] may provide an efficient and scalable solution for the
solution for the fast-converging environment that has head-tails fast-converging environment that demonstrates the head-tails
relationships. 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 BFD Discriminator TLV p2mp BFD session. Figure 1 displays the new optional BFD
[RFC7761] to bootstrap tail of the p2mp BFD session. Discriminator TLV 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 TLV to Bootstrap P2MP BFD session
skipping to change at page 4, line 25 skipping to change at page 4, line 25
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.
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 MultipointHead, as referred to as 'head', MUST create BFD session of type
defined in [I-D.ietf-bfd-multipoint]. The head MUST include BFD TLV MultipointHead, as defined in [RFC8562]. If the head doesn't support
in its PIM-Hello message and periodically transmit BFD control [I-D.ietf-pim-dr-improvement], then it MUST include BFD TLV in its
packets. Source IP address of the BFD control packet MUST be the PIM-Hello message. If the head uses extensions defined in
same as the source IP address of the PIM-Hello with BFD TLV messages [I-D.ietf-pim-dr-improvement], then DR MUST include BFD TLV in its
being transmitted by the head. The values of My Discriminator in the Hello message after the DR Address TLV. For a BDR it is RECOMMENDED
BFD control packet and My Discriminator field of the BFD TLV in PIM- to include BFD TLV in its Hello message. If BDR includes BFD TLV,
Hello, transmitted by the head MUST be the same. When a PIM-SM then it MUST be after the BDR Address TLV. Then the head MUST begin
router configured to monitor the head, referred to as 'tail', via periodic transmission of BFD control packets. Source IP address of
p2mp BFD receives PIM-Hello packet with BFD TLV it MAY create p2mp the BFD control packet MUST be the same as the source IP address of
BFD session as MultipointTail, as defined in the PIM-Hello with BFD TLV messages being transmitted by the head.
[I-D.ietf-bfd-multipoint], and demultiplex p2mp BFD test session The values of My Discriminator in the BFD control packet and My
based on head's source IP address the My Discriminator value it Discriminator field of the BFD TLV in PIM-Hello, transmitted by the
learned from BFD Discriminator TLV. If the head ceased to include head MUST be the same. When a PIM-SM router is configured to monitor
BFD TLV in its PIM-Hello message, tails MUST close the corresponding the head by using p2p BFD, referred to through this document as
MultipointTail BFD session. If the tail detects MultipointHead 'tail', receives PIM-Hello packet with BFD TLV it MAY create p2mp BFD
failure it MUST remove the neighbor. If the failed head node was session of type MultipointTail, as defined in [RFC8562].
PIM-SM DR or BDR the tail MAY start DR Election process as specified
in Section 4.3.2 [RFC7761] or in Section 4.1 Because p2mp BFD doesn't use the three-way handshake and the head
[I-D.ietf-pim-dr-improvement] respectively. transmits BFD control packets with the value of Your Discriminator
field set to zero, [RFC8562] modified how a BFD system demultiplexes
received BFD control packet. The tail demultiplexes p2mp BFD test
session based on head's source IP address, the My Discriminator value
it learned from BFD Discriminator TLV and the identity of the
multipoint path that the BFD control packet was received from. The
Detection Time for p2mp BFD sessions is defined differently from the
definition provided in [RFC5880]. The Detection Time for each
MultipointTail session is calculated as the product of the last
received values of Desired Min TX Interval and Detect Mult. A tail
declares the BFD session down after the Detection Timer expires. If
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
start DR Election process as specified in Section 4.3.2 [RFC7761] or
Section 4.1 [I-D.ietf-pim-dr-improvement] respectively.
If the head ceased to include BFD TLV in its PIM-Hello message, tails
MUST close the corresponding MultipointTail BFD session. Thus the
tail stops using BFD to monitor the head and reverts to the
procedures defined in [RFC7761] and [I-D.ietf-pim-dr-improvement].
3.1. Multipoint BFD Encapsulation 3.1. 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
multicast group for IPv6 as the destination IP address; multicast group for IPv6 as the destination IP address;
MUST set destination UDP port value to 3784 when transmitting BFD MUST set destination UDP port value to 3784 when transmitting BFD
control packets, as defined in [I-D.ietf-bfd-multipoint]. control packets, as defined in [RFC8562].
4. IANA Considerations 4. IANA Considerations
IANA is requested to allocate a new OptionType value from PIM Hello IANA is requested to allocate a new OptionType value from PIM Hello
Options registry according to: Options registry according to:
+-------------+----------------+-------------------+---------------+ +-------------+----------------+-------------------+---------------+
| Value Name | Length Number | Name Protocol | Reference | | Value Name | Length Number | Name Protocol | Reference |
+-------------+----------------+-------------------+---------------+ +-------------+----------------+-------------------+---------------+
| TBA | 4 | BFD Discriminator | This document | | TBA | 4 | BFD Discriminator | This document |
+-------------+----------------+-------------------+---------------+ +-------------+----------------+-------------------+---------------+
Table 1: BFD Discriminator option type Table 1: BFD Discriminator option type
5. Security Considerations 5. Security Considerations
Security considerations discussed in [RFC7761], [RFC5880], and Security considerations discussed in [RFC7761], [RFC5880], and
[I-D.ietf-bfd-multipoint], apply to this document. [RFC8562], and [I-D.ietf-pim-dr-improvement] apply to this document.
An implementation that supports this specification SHOULD use a
mechanism to control the maximum number of BFD sessions that can be
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. Normative References
[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.
[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-05 (work in Improvement", draft-ietf-pim-dr-improvement-07 (work in
progress), June 2018. progress), January 2019.
[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 6, line 33 skipping to change at page 6, line 49
[RFC7761] Fenner, B., Handley, M., Holbrook, H., Kouvelas, I., [RFC7761] Fenner, B., Handley, M., Holbrook, H., Kouvelas, I.,
Parekh, R., Zhang, Z., and L. Zheng, "Protocol Independent Parekh, R., Zhang, Z., and L. Zheng, "Protocol Independent
Multicast - Sparse Mode (PIM-SM): Protocol Specification Multicast - Sparse Mode (PIM-SM): Protocol Specification
(Revised)", STD 83, RFC 7761, DOI 10.17487/RFC7761, March (Revised)", STD 83, RFC 7761, DOI 10.17487/RFC7761, March
2016, <https://www.rfc-editor.org/info/rfc7761>. 2016, <https://www.rfc-editor.org/info/rfc7761>.
[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,
Ed., "Bidirectional Forwarding Detection (BFD) for
Multipoint Networks", RFC 8562, DOI 10.17487/RFC8562,
April 2019, <https://www.rfc-editor.org/info/rfc8562>.
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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