Internet DRAFT - draft-mankamana-pim-pfm-sd-extension-evpn-mh
draft-mankamana-pim-pfm-sd-extension-evpn-mh
PIM Working Group M. Mishra
Internet-Draft Cisco
Intended status: Standards Track I. Wijnands
Expires: 20 April 2024 Individual
R. Tucker
Charter
H. Bidgoli
Nokia
Z. Zhang
Juniper Networks
18 October 2023
PFM-SD extension for EVPN multi-homing
draft-mankamana-pim-pfm-sd-extension-evpn-mh-00
Abstract
Ethernet Virtual Private Network (EVPN) solution is becoming
pervasive in data center (DC) applications for Network Virtualization
Overlay (NVO) and DC interconnect (DCI) services and in service
provider (SP) applications for next-generation virtual private LAN
services.
EVPN defines sets of procedures to achieve multihoming between peers.
When the multicast source is protected by EVPN multihoming for
redundancy and multicast receivers are present behind PIM network,
there are cases where traffic blackholes.
PIM Flooding Mechanism (PFM) and Source Discovery (SD) define new
flood mechanisms in PIM domain to carry information about source and
group. This draft defines the necessary extension to PFM-SD
procedures to have seamless integration with EVPN supported
multihoming.
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.
Status of This Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Requirements Language . . . . . . . . . . . . . . . . . . . . 4
3. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 4
4. Problem Statement . . . . . . . . . . . . . . . . . . . . . . 4
5. Solution Requirement . . . . . . . . . . . . . . . . . . . . 6
6. Solution overview . . . . . . . . . . . . . . . . . . . . . . 7
6.1. Flooding multihome source . . . . . . . . . . . . . . . . 7
6.2. Optimization multihome source flooding . . . . . . . . . 7
7. Security Considerations . . . . . . . . . . . . . . . . . . . 7
8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 7
9. References . . . . . . . . . . . . . . . . . . . . . . . . . 7
9.1. Normative References . . . . . . . . . . . . . . . . . . 7
9.2. Informative References . . . . . . . . . . . . . . . . . 8
Appendix A. Acknowledgments . . . . . . . . . . . . . . . . . . 8
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 8
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1. Introduction
[RFC7432] describes procedures for BGP MPLS-based Ethernet VPNs
(EVPN). It defines the function, procedure, and associated BGP
routes used to support multihoming in EVPN. It defines the concept
of Ethernet Segment (ES) which is a virtual construct to drive BGP
procedures to be able to determine if two provider edge are
multihomed.
+--------------+ +-------------+
| | | |
| PE1 | | PE2 |
| | | |
+---------+----+ +-----+-------+
\ /
\ /
\ /
\ /
\ /
+-\----------------/-+
| \ / |
+---\------------/---+
\ /
\ /
+-------------+
| |
| CE |
+-------------+
The above figure shows a sample multihoming case. where two
independent PE (Provider Edge) are connected to CE (customer edge)
devices via MC-LAG. Any packets that are originating from CE or host
attached to CE can be hashed to either of the PE. and PE would have
no knowledge about who can get any packets.
[RFC8364] defines a generic flooding mechanism for distributing
information throughout a PIM domain.
Many deployments do use EVPN multihoming to achieve redundancy of
reachability in the network. When EVPN multihoming is deployed with
PIM [RFC7761] network, there is challenge with respect to RPF
selection by PIM domain. This draft defines a necessary extension to
[RFC8364] to achieve optimal multicast forwarding in PIM domain.
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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. Terminology
BD: test
4. Problem Statement
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Multicast Receiver
|
|
| PIM (1 .1.1.1, 232.1.1.1)
|
|
+---------------+
| P2 |
| |
+---------------+
|
PIM join (10.1.1.1, 232.1.1.1) |
| Unicast Rechability
+--------------+ Prefix 10.1.1.0/24
| P1 | NH : PE1, PE2 (ECMP)
| |
+--------------+
/\
/ \
/ \
/ \ PIM (10.1.1.1, 232.1.1.1)
/ \
/ \
/ \
- -
+-------------+ +-------------+
| PE1 | | PE2 |
| | | |
IRB 10.1.1.0/24 +-------------+ +-------------+IRB 10.1.1.0/24
\ /
\ /
\ /
\ /
\ /
\ /
- -
+--------------------+
| CE |
| |
+--------------------+
|
|
|
Source 10.1.1.1
Above figure shows sample topology where
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* CE is multihomed to PE1 and PE2
* EVPN gets terminated over IRB in both of the PE
* North of the PE is PIM domain
* Multicast receiver originates PIM join towards source
In the above topology, the source prefix is announced in IGP from
both of the PE. When P1 does process PIM joins towards source
10.1.1.1, it needs to do a source prefix lookup to pick RPF towards
the source. Since there is ECMP path, it gets two next hop as PE1
and PE2. Based on local decision P1 can send PIM join to either of
the next hop. Consider in this case it picks PE2 as RPF to send PIM
join. At this point of time end to end PIM tree has been created
where the tree is built rooted at PE2. At present there is no data
traffic being sourced.
As the next step Source starts sending multicast traffic. Once
traffic reaches CE, it is going to hash the flow to either of the
ports. and consider it picks PE1 as the next hop to send traffic to.
Previous two steps (PIM join and multicast data flow) can happen in
any order
At the end we are in a situation where multicast traffic is being
received by PE1 and PIM join landed on PE2 causing traffic
blackholing.
At present deployment uses EVPN BUM tunnel to bridge multicast
traffic between peers. Which results in traffic from PE1 being
bridged to PE2 via P1. and it leads same traffic going over the link
twice (once as bridge copy and once as routed copy).
5. Solution Requirement
* It MUST avoid traffic duplication between peers unless there are
local receivers
* It MUST be applicable for PIM-SM and PIM-SSM
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6. Solution overview
[[RFC8364] defines a generic flooding mechanism for distributing
information throughout the PIM domain. Multicast source discovery
was one of the types of information being flooded in the PIM domain.
[RFC8364] was mainly designed to flood source information for PIM-SM
sources. However, this draft provides an extension to flood PIM-SM
and PIM-SSM source information if the source is being hosted in a
multihomed port.
6.1. Flooding multihome source
Multihome source flood will use a generic flood mechanism defined by
[RFC8364]. Forwarding rules are identical to [RFC8364]
Details of TLV extension and packet format are to be added in the
next revision.
6.2. Optimization multihome source flooding
TBD
7. Security Considerations
8. IANA Considerations
9. References
9.1. Normative References
[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>.
[RFC7432] Sajassi, A., Ed., Aggarwal, R., Bitar, N., Isaac, A.,
Uttaro, J., Drake, J., and W. Henderickx, "BGP MPLS-Based
Ethernet VPN", RFC 7432, DOI 10.17487/RFC7432, February
2015, <https://www.rfc-editor.org/info/rfc7432>.
[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>.
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[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>.
[RFC8364] Wijnands, IJ., Venaas, S., Brig, M., and A. Jonasson, "PIM
Flooding Mechanism (PFM) and Source Discovery (SD)",
RFC 8364, DOI 10.17487/RFC8364, March 2018,
<https://www.rfc-editor.org/info/rfc8364>.
9.2. Informative References
Appendix A. Acknowledgments
Authors' Addresses
Mankamana Mishra
Cisco
Email: mankamis@cisco.com
IJsbrand Wijnands
Individual
Email: ice@braindump.be
Ryan R Tucker
Charter
Email: Ryan.Tucker@charter.com
Hooman Bidgoli
Nokia
Email: hooman.bidgoli@nokia.com
Zhaohui Zhang
Juniper Networks
Email: zzhang@juniper.net
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