Internet DRAFT - draft-ssm-bess-bgp-ec-evpn-vpws
draft-ssm-bess-bgp-ec-evpn-vpws
BESS R. Srikanth
Internet-Draft R. Satishkumar
Intended status: Standards Track M. Perumal
Expires: September 8, 2019 Ericsson
March 7, 2019
BGP Extended Community for Virtual Private Wire Service Support in
Ethernet VPN
draft-ssm-bess-bgp-ec-evpn-vpws-00
Abstract
This document describes an optional BGP extended community for use in
Ethernet VPN (EVPN) Virtual Private Wire Service (VPWS). It helps in
avoiding the situation where the EVPN VPWS instance is declared 'up'
on one side but remains 'down' on the other side.
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the Trust Legal Provisions and are provided without warranty as
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 2
3. Problem Description . . . . . . . . . . . . . . . . . . . . . 3
4. Remote VPWS Instance Identifier Extended Community . . . . . 3
5. Usage of the Extended Community . . . . . . . . . . . . . . . 4
6. Security Considerations . . . . . . . . . . . . . . . . . . . 4
7. IANA Considerationss . . . . . . . . . . . . . . . . . . . . 5
8. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 5
9. Normative References . . . . . . . . . . . . . . . . . . . . 5
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 5
1. Introduction
In EVPN, a VPWS service instance is identified by a pair of per-EVI
Ethernet A-D routes as described in [RFC8214]. Each Provider Edge
(PE) node that wants to instantiate a VPWS service instance encodes
the VPWS service instance identifier in the 32-bit Ethernet Tag ID
field of the per-EVI Ethernet A-D route.
The pair of PEs instantiating a VPWS service instance will each
advertise a per-EVI Ethernet A-D route with its VPWS service instance
identifier. Each PE is also configured with the other PE's VPWS
service instance identifier. When each PE receives the other PE's
per-EVI Ethernet A-D route with the VPWS service instance identifier
of the other PE configured on each PE, the VPWS service instance is
instantiated.
However, if the VPWS service identifiers are misconfigured on either
of the PEs, it can result in a situation where the EVPN VPWS service
instance is declared 'up' on one PE but remains 'down' on the other
PE.
This document describes an optional BGP extended community for use in
VPWS that can be used to avoid the above situation.
2. Terminology
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.
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o EVPN: Ethernet VPN.
o PE: Provider Edge Node.
o VPWS: Virtual Private Wire Service defined in [RFC8214].
o LSI: Local VPWS service instance identifier.
o RSI: Remote VPWS service instance identifier.
o EC: Extended Community.
3. Problem Description
Consider a case where PE1 and PE2 wants to instantiate a EVPN VPWS
service instance with the following configurations:
o PE1 is configured with Local VPWS service instance identifier
(LSI) as 100 and Remote VPWS service instance identifier (RSI) as
200.
o PE2 is configured with LSI as 300 and RSI as 100.
With this setup:
o PE1 will receive the per-EVI Ethernet A-D route from PE2 with
Ethernet Tag ID as 300.
o PE2 will receive the per-EVI Ethernet A-D route from PE1 with
Ethernet Tag ID as 100.
Though it is a misconfiguration, the EVPN VPWS service instance on
PE2 will come up and PE2 will start forwarding traffic towards PE1.
However, the EVPN VPWS service instance on PE1 will remain down.
This may be undesirable (for example, it can resulting in wastage of
network bandwidth).
4. Remote VPWS Instance Identifier Extended Community
This document defines a new transitive extended community [RFC4360]
to be included with per-EVI Ethernet A-D routes. This attribute is
optional and can be used to avoid the situation described in
Section 3.
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+-------------------------------------------+
| Type (0x06) / Sub-type (TBD) (2 octets) |
+-------------------------------------------+
| Remote Service ID (4 octets) |
| |
+-------------------------------------------+
Figure 1: EVPN VPWS Extended Community for remote service ID.
Remote Service ID: This field MUST be set to the VPWS service
instance identifier value of the remote PE (RSI). The VPWS service
instance identifier value MAY be set to a 24-bit value, and when a
24-bit value is used, it MUST be right-aligned.
5. Usage of the Extended Community
Consider the following setup:
+------------+ +------------+
| PE1 | | PE2 |
| (LSI: 100) |-------| (LSI: 200) |
| (RSI: 200) | | (RSI: 100) |
+------------+ +------------+
Figure 2: Network Topology for EVPN-VPWS
EVPN-VPWS as described in [RFC8214] only exchange LSI value along
with local label. In this case PE1 will send a per-EVI Ethernet A-D
route with LSI 100 and PE2 will send a per-EVI Ethernet A-D route
with LSI 200.
With the extended community described in this document, PE1 sends the
per-EVI Ethernet A-D route with LSI 100 and RSI 200 and PE2 sends the
per-EVI Ethernet A-D route with LSI 200 and RSI 100.
PE1 upon receiving the per-EVI Ethernet A-D route will bring up the
EVPN VPWS service instance only if the LSI and RSI received in the
route matches the LSI and RSI configured on PE1. Otherwise, PE1
keeps the EVPN VPWS service instance as down.
6. Security Considerations
The security considerations described in RFC8214 apply to this
document.
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7. IANA Considerationss
This document requests IANA to assign a new EVPN Extended Community
of Type 0x06 and Sub-Type TBD:
Sub-Type Value Name Reference
---------------------------------------------------------------
TBD Remote VPWS Instance Identifier This document
8. Acknowledgments
Thanks to Chundu Kotesh Babu and Jiang He for comments and
suggestions.
9. 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>.
[RFC4360] Sangli, S., Tappan, D., and Y. Rekhter, "BGP Extended
Communities Attribute", RFC 4360, DOI 10.17487/RFC4360,
February 2006, <https://www.rfc-editor.org/info/rfc4360>.
[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>.
[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>.
[RFC8214] Boutros, S., Sajassi, A., Salam, S., Drake, J., and J.
Rabadan, "Virtual Private Wire Service Support in Ethernet
VPN", RFC 8214, DOI 10.17487/RFC8214, August 2017,
<https://www.rfc-editor.org/info/rfc8214>.
Authors' Addresses
Srikanth Ramaswamy
Ericsson
Bangalore
India
Email: srikanth@ericsson.com
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Satishkumar Rodd
Ericsson
Bangalore
India
Email: satishkumar.n.rodd@ericsson.com
Muthu Arul Mozhi Perumal
Ericsson
Bangalore
India
Email: muthu.arul@gmail.com
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