BESS Working Group K. Ananthamurthy
Internet-Draft A. Sajassi
Intended status: Standards Track L. Krattiger
Expires: 4 September 2025 Cisco
3 March 2025
Per-flow based EVPN DF Election
draft-kriswamy-bess-evpn-perflow-df-00
Abstract
The Ethernet Virtual Private Network (EVPN) solution offers
procedures for electing a Designated Forwarder (DF) for multihomed
Ethernet Segments. In this context, the Provider Edge (PE) router is
responsible for sending Broadcast, Unknown Unicast, and Multicast
(BUM) traffic to a multihomed device or network. This applies in
cases of an all-active multihomed Ethernet Segment (ES) as well as
for BUM and unicast traffic in the case of single-active multi-
homing. While the Default Algorithm provides an efficient and
automated way of selecting the DF across different Ethernet Tags in
the Ethernet Segment, but lacks in providing per flow based DF within
the given EVPN Instances (EVIs).
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.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet-
Drafts is at https://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress."
This Internet-Draft will expire on 4 September 2025.
Ananthamurthy, et al. Expires 4 September 2025 [Page 1]
Internet-Draft Per-flow based EVPN DF Election March 2025
Copyright Notice
Copyright (c) 2025 IETF Trust and the persons identified as the
document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents (https://trustee.ietf.org/
license-info) in effect on the date of publication of this document.
Please review these documents carefully, as they describe your rights
and restrictions with respect to this document. Code Components
extracted from this document must include Revised BSD License text as
described in Section 4.e of the Trust Legal Provisions and are
provided without warranty as described in the Revised BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Requirements Language . . . . . . . . . . . . . . . . . . . . 3
3. Designated Forwarder Election Extended Community
Extensions . . . . . . . . . . . . . . . . . . . . . . . 3
4. Operation . . . . . . . . . . . . . . . . . . . . . . . . . . 3
5. Security Considerations . . . . . . . . . . . . . . . . . . . 4
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 4
7. Normative References . . . . . . . . . . . . . . . . . . . . 4
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 5
1. Introduction
The Ethernet Virtual Private Network (EVPN) solution offers
procedures for electing a Designated Forwarder (DF) for multihomed
Ethernet Segments. In this context, the Provider Edge (PE) router is
responsible for sending Broadcast, Unknown Unicast, and Multicast
(BUM) traffic to a multihomed device or network. This applies in
cases of an all-active multihomed Ethernet Segment (ES) as well as
for BUM and unicast traffic in the case of single-active multi-
homing. While the Default Algorithm provides an efficient and
automated way of selecting the DF across different Ethernet Tags in
the Ethernet Segment, but lacks in providing per flow based DF within
the given EVPN Instances (EVIs).
This document proposes a Per-flow DF Election algorithm to provide
optimal load sharing. This document updates RFC8584 by modifying the
definition of the DF Election Extended Community with new DF
Algorithm type.
Ananthamurthy, et al. Expires 4 September 2025 [Page 2]
Internet-Draft Per-flow based EVPN DF Election March 2025
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. Designated Forwarder Election Extended Community Extensions
This solution reuses and extends the Designated Forwarder Election
Extended Community defined in [RFC8584] that is advertised along with
the Ethernet Segment route. This document defines a new DF Algorithm
type Per-flow. The format of the DF Election Extended Community that
is used in this document follows:
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=0x06 | Sub-Type(0x06)| RSV | DF Alg | Bitmap ~
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
~ Bitmap | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 1: DF Election Extended Community
DF Alg will carry the DF alg type.
New DF Alg type called per-flow df with value 6 (to be allocated by
IANA) will be defined in the draft and same will be encoded in DF
algorithm EC.
The procedures defined in [RFC8584] to handle Designated Forwarder
Election Extended Community are applicable.
When a PE receives the ES routes from all the other PEs for the ES in
question, it checks to see if all the advertisements have the
Extended Community with the same DF Alg, then it will operate in per-
flow DF algorithm.
4. Operation
When PE supports the Per-flow DF algorithm, the ES route is sent with
the DF Election Extended Community, with DF-Alg set to Per-flow.
When PE supports the Per-flow DF algorithm, it should use the DF
election as per the flow when it receives the ES route with the DF
Election Extended Community and the DF-Alg set to Per-flow.
Ananthamurthy, et al. Expires 4 September 2025 [Page 3]
Internet-Draft Per-flow based EVPN DF Election March 2025
PE, which does not support Per-flow DF, will revert to the default
modulo-based DF.
When a Provider Edge (PE) router operates in Per-Flow Designated
Forwarder (DF) mode, it computes a hash based on the five-tuple of
the packet header. The hashing algorithm can use a Cyclic Redundancy
Check (CRC). The number of PEs involved in redundancy multihoming
will be used in the calculation as follows: I, which is HASH mod N.
This approach allows multiple flows within a given VLAN to be
forwarded by different PEs acting as DF for a specific Ethernet
Segment (ES).
5. Security Considerations
TBD
6. IANA Considerations
This document solicits:
* The allocation of two new values in the "DF Alg" registry created
by [RFC8584] as follows:
Alg Name Reference
---- ----------------------------- -------------
6 Per-flow Algorithm This document
7. Normative References
[I-D.ietf-bess-evpn-virtual-eth-segment]
Sajassi, A., Brissette, P., Schell, R., Drake, J., and J.
Rabadan, "EVPN Virtual Ethernet Segment", Work in
Progress, Internet-Draft, draft-ietf-bess-evpn-virtual-
eth-segment-19, 9 December 2024,
<https://datatracker.ietf.org/doc/html/draft-ietf-bess-
evpn-virtual-eth-segment-19>.
[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>.
Ananthamurthy, et al. Expires 4 September 2025 [Page 4]
Internet-Draft Per-flow based EVPN DF Election March 2025
[RFC7606] Chen, E., Ed., Scudder, J., Ed., Mohapatra, P., and K.
Patel, "Revised Error Handling for BGP UPDATE Messages",
RFC 7606, DOI 10.17487/RFC7606, August 2015,
<https://www.rfc-editor.org/info/rfc7606>.
[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>.
[RFC8584] Rabadan, J., Ed., Mohanty, S., Ed., Sajassi, A., Drake,
J., Nagaraj, K., and S. Sathappan, "Framework for Ethernet
VPN Designated Forwarder Election Extensibility",
RFC 8584, DOI 10.17487/RFC8584, April 2019,
<https://www.rfc-editor.org/info/rfc8584>.
Authors' Addresses
Krishnaswamy Ananthamurthy
Cisco
170 W. Tasman Drive
San Jose, CA 95134
United States of America
Email: kriswamy@cisco.com
Ali Sajassi
Cisco
170 W. Tasman Drive
San Jose, CA 95134
United States of America
Email: sajassi@cisco.com
Lukas Krattiger
Cisco
170 W. Tasman Drive
San Jose, CA 95134
United States of America
Email: lkrattig@cisco.com
Ananthamurthy, et al. Expires 4 September 2025 [Page 5]