draft-ietf-bess-evpn-unequal-lb-04.txt   draft-ietf-bess-evpn-unequal-lb-05.txt 
BESS WorkGroup N. Malhotra, Ed. BESS WorkGroup N. Malhotra, Ed.
Internet-Draft A. Sajassi Internet-Draft A. Sajassi
Intended status: Standards Track Cisco Systems Intended status: Standards Track Cisco Systems
Expires: November 18, 2020 J. Rabadan Expires: January 11, 2021 J. Rabadan
Nokia Nokia
J. Drake J. Drake
Juniper Juniper
A. Lingala A. Lingala
ATT ATT
S. Thoria S. Thoria
Cisco Systems Cisco Systems
May 17, 2020 July 10, 2020
Weighted Multi-Path Procedures for EVPN All-Active Multi-Homing Weighted Multi-Path Procedures for EVPN All-Active Multi-Homing
draft-ietf-bess-evpn-unequal-lb-04 draft-ietf-bess-evpn-unequal-lb-05
Abstract Abstract
In an EVPN-IRB based network overlay, EVPN all-active multi-homing In an EVPN-IRB based network overlay, EVPN all-active multi-homing
enables multi-homing for a CE device connected to two or more PEs via enables multi-homing for a CE device connected to two or more PEs via
a LAG bundle, such that bridged and routed traffic from remote PEs a LAG, such that bridged and routed traffic from remote PEs can be
can be equally load balanced (ECMPed) across the multi-homing PEs. equally load balanced (ECMPed) across the multi-homing PEs. This
This document defines extensions to EVPN procedures to optimally document defines extensions to EVPN procedures to optimally handle
handle unequal access bandwidth distribution across a set of multi- unequal access bandwidth distribution across a set of multi-homing
homing PEs in order to: PEs in order to:
o provide greater flexibility, with respect to adding or removing o provide greater flexibility, with respect to adding or removing
individual PE-CE links within the access LAG. individual PE-CE links within the access LAG.
o handle PE-CE LAG member link failures that can result in unequal o handle PE-CE LAG member link failures that can result in unequal
PE-CE access bandwidth across a set of multi-homing PEs. PE-CE access bandwidth across a set of multi-homing PEs.
Status of This Memo Status of This Memo
This Internet-Draft is submitted in full conformance with the This Internet-Draft is submitted in full conformance with the
skipping to change at page 2, line 4 skipping to change at page 2, line 4
Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet- working documents as Internet-Drafts. The list of current Internet-
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Internet-Drafts are draft documents valid for a maximum of six months Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress." material or to cite them other than as "work in progress."
This Internet-Draft will expire on November 18, 2020. This Internet-Draft will expire on January 11, 2021.
Copyright Notice Copyright Notice
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document authors. All rights reserved. document authors. All rights reserved.
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Table of Contents Table of Contents
1. Requirements Language and Terminology . . . . . . . . . . . . 3 1. Requirements Language and Terminology . . . . . . . . . . . . 3
2. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3 2. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
2.1. PE CE Link Provisioning . . . . . . . . . . . . . . . . . 4 2.1. PE-CE Link Provisioning . . . . . . . . . . . . . . . . . 4
2.2. PE CE Link Failures . . . . . . . . . . . . . . . . . . . 5 2.2. PE-CE Link Failures . . . . . . . . . . . . . . . . . . . 5
2.3. Design Requirement . . . . . . . . . . . . . . . . . . . 6 2.3. Design Requirement . . . . . . . . . . . . . . . . . . . 6
2.4. Terminology . . . . . . . . . . . . . . . . . . . . . . . 6 3. Solution Overview . . . . . . . . . . . . . . . . . . . . . . 6
3. Solution Overview . . . . . . . . . . . . . . . . . . . . . . 7
4. Weighted Unicast Traffic Load-balancing . . . . . . . . . . . 7 4. Weighted Unicast Traffic Load-balancing . . . . . . . . . . . 7
4.1. LOCAL PE Behavior . . . . . . . . . . . . . . . . . . . . 7 4.1. Local PE Behavior . . . . . . . . . . . . . . . . . . . . 7
4.2. Link Bandwidth Extended Community . . . . . . . . . . . . 7 4.2. Link Bandwidth Extended Community . . . . . . . . . . . . 7
4.3. REMOTE PE Behavior . . . . . . . . . . . . . . . . . . . 8 4.3. Remote PE Behavior . . . . . . . . . . . . . . . . . . . 7
5. Weighted BUM Traffic Load-Sharing . . . . . . . . . . . . . . 9 5. Weighted BUM Traffic Load-Sharing . . . . . . . . . . . . . . 9
5.1. The BW Capability in the DF Election Extended Community . 9 5.1. The BW Capability in the DF Election Extended Community . 9
5.2. BW Capability and Default DF Election algorithm . . . . . 10 5.2. BW Capability and Default DF Election algorithm . . . . . 10
5.3. BW Capability and HRW DF Election algorithm (Type 1 and 5.3. BW Capability and HRW DF Election algorithm (Type 1 and
4) . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 4) . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
5.3.1. BW Increment . . . . . . . . . . . . . . . . . . . . 10 5.3.1. BW Increment . . . . . . . . . . . . . . . . . . . . 10
5.3.2. HRW Hash Computations with BW Increment . . . . . . . 11 5.3.2. HRW Hash Computations with BW Increment . . . . . . . 11
5.3.3. Cost-Benefit Tradeoff on Link Failures . . . . . . . 12
5.4. BW Capability and Weighted HRW DF Election algorithm 5.4. BW Capability and Weighted HRW DF Election algorithm
(Type TBD) . . . . . . . . . . . . . . . . . . . . . . . 13 (Type TBD) . . . . . . . . . . . . . . . . . . . . . . . 13
5.5. BW Capability and Preference DF Election algorithm . . . 14 5.5. BW Capability and Preference DF Election algorithm . . . 13
6. Real-time Available Bandwidth . . . . . . . . . . . . . . . . 14 6. Cost-Benefit Tradeoff on Link Failures . . . . . . . . . . . 14
7. Routed EVPN Overlay . . . . . . . . . . . . . . . . . . . . . 14 7. Real-time Available Bandwidth . . . . . . . . . . . . . . . . 14
8. EVPN-IRB Multi-homing with non-EVPN routing . . . . . . . . . 15 8. Routed EVPN Overlay . . . . . . . . . . . . . . . . . . . . . 14
9. Operational Considerations . . . . . . . . . . . . . . . . . 15 9. EVPN-IRB Multi-homing With Non-EVPN routing . . . . . . . . . 15
10. Security Considerations . . . . . . . . . . . . . . . . . . . 16 10. Operational Considerations . . . . . . . . . . . . . . . . . 15
11. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 16 11. Security Considerations . . . . . . . . . . . . . . . . . . . 16
12. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 16 12. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 16
13. Normative References . . . . . . . . . . . . . . . . . . . . 16 13. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 16
14. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 16
15. Normative References . . . . . . . . . . . . . . . . . . . . 16
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 17 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 17
1. Requirements Language and Terminology 1. Requirements Language and Terminology
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in [RFC2119]. document are to be interpreted as described in [RFC2119].
"Local PE" in the context of an ESI refers to a provider edge switch
OR router that physically hosts the ESI.
"Remote PE" in the context of an ESI refers to a provider edge switch
OR router in an EVPN overlay, whose overlay reachability to the ESI
is via the Local PE.
o BW: Band-Width
o LAG: Link Aggregation Group
o ES: Ethernet Segment o ES: Ethernet Segment
o vES: Virtual Ethernet Segment o vES: Virtual Ethernet Segment
o EVI: Ethernet virtual Instance, this is a mac-vrf. o EVI: Ethernet virtual Instance, this is a mac-vrf.
o IMET: Inclusive Multicast Route o IMET: Inclusive Multicast Route
o DF: Designated Forwarder o DF: Designated Forwarder
skipping to change at page 3, line 44 skipping to change at page 4, line 8
o ECMP Load-balancing for bridged unicast traffic is enabled via o ECMP Load-balancing for bridged unicast traffic is enabled via
o aliasing and mass-withdraw procedures detailed in RFC 7432. o aliasing and mass-withdraw procedures detailed in RFC 7432.
o ECMP Load-balancing for routed unicast traffic is enabled via o ECMP Load-balancing for routed unicast traffic is enabled via
existing L3 ECMP mechanisms. existing L3 ECMP mechanisms.
o Load-sharing of bridged BUM traffic on local ports is enabled via o Load-sharing of bridged BUM traffic on local ports is enabled via
EVPN DF election procedure detailed in RFC 7432 EVPN DF election procedure detailed in RFC 7432
All of the above load-balancing and DF election procedures implicitly All of the above load balancing and DF election procedures implicitly
assume equal bandwidth distribution between the CE and the set of assume equal bandwidth distribution between the CE and the set of
multi-homing PEs. Essentially, with this assumption of equal multi-homing PEs. Essentially, with this assumption of equal
"access" bandwidth distribution across all PEs, ALL remote traffic is "access" bandwidth distribution across all PEs, ALL remote traffic is
equally load balanced across the multi-homing PEs. This assumption equally load balanced across the multi-homing PEs. This assumption
of equal access bandwidth distribution can be restrictive with of equal access bandwidth distribution can be restrictive with
respect to adding / removing links in a multi-homed LAG interface and respect to adding / removing links in a multi-homed LAG interface and
may also be easily broken on individual link failures. A solution to may also be easily broken on individual link failures. A solution to
handle unequal access bandwidth distribution across a set of multi- handle unequal access bandwidth distribution across a set of multi-
homing EVPN PEs is proposed in this document. Primary motivation homing EVPN PEs is proposed in this document. Primary motivation
behind this proposal is to enable greater flexibility with respect to behind this proposal is to enable greater flexibility with respect to
adding / removing member PE-CE links, as needed and to optimally adding / removing member PE-CE links, as needed and to optimally
handle PE-CE link failures. handle PE-CE link failures.
2.1. PE CE Link Provisioning 2.1. PE-CE Link Provisioning
+------------------------+ +------------------------+
| Underlay Network Fabric| | Underlay Network Fabric|
+------------------------+ +------------------------+
+-----+ +-----+ +-----+ +-----+
| PE1 | | PE2 | | PE1 | | PE2 |
+-----+ +-----+ +-----+ +-----+
\ / \ /
\ ESI-1 / \ ESI-1 /
\ / \ /
+\---/+ +\---/+
| \ / | | \ / |
+--+--+ +--+--+
| |
CE1 CE1
Figure 1 Figure 1
Consider a CE1 that is dual-homed to PE1 and PE2 via EVPN all-active Consider CE1 that is dual-homed to PE1 and PE2 via EVPN all-active
multi-homing with single member links of equal bandwidth to each PE multi-homing with single member links of equal bandwidth to each PE
(aka, equal access bandwidth distribution across PE1 and PE2). If (aka, equal access bandwidth distribution across PE1 and PE2). If
the provider wants to increase link bandwidth to CE1, it MUST add a the provider wants to increase link bandwidth to CE1, it must add a
link to both PE1 and PE2 in order to maintain equal access bandwidth link to both PE1 and PE2 in order to maintain equal access bandwidth
distribution and inter-work with EVPN ECMP load-balancing. In other distribution and inter-work with EVPN ECMP load balancing. In other
words, for a dual-homed CE, total number of CE links must be words, for a dual-homed CE, total number of CE links must be
provisioned in multiples of 2 (2, 4, 6, and so on). For a triple- provisioned in multiples of 2 (2, 4, 6, and so on). For a triple-
homed CE, number of CE links must be provisioned in multiples of homed CE, number of CE links must be provisioned in multiples of
three (3, 6, 9, and so on). To generalize, for a CE that is multi- three (3, 6, 9, and so on). To generalize, for a CE that is multi-
homed to "n" PEs, number of PE-CE physical links provisioned must be homed to "n" PEs, number of PE-CE physical links provisioned must be
an integral multiple of "n". This is restrictive in case of dual- an integral multiple of "n". This is restrictive in case of dual-
homing and very quickly becomes prohibitive in case of multi-homing. homing and very quickly becomes prohibitive in case of multi-homing.
Instead, a provider may wish to increase PE-CE bandwidth OR number of Instead, a provider may wish to increase PE-CE bandwidth OR number of
links in ANY link increments. As an example, for CE1 dual-homed to links in any link increments. As an example, for CE1 dual-homed to
PE1 and PE2 in all-active mode, provider may wish to add a third link PE1 and PE2 in all-active mode, provider may wish to add a third link
to ONLY PE1 to increase total bandwidth for this CE by 50%, rather to only PE1 to increase total bandwidth for this CE by 50%, rather
than being required to increase access bandwidth by 100% by adding a than being required to increase access bandwidth by 100% by adding a
link to each of the two PEs. While existing EVPN based all-active link to each of the two PEs. While existing EVPN based all-active
load-balancing procedures do not necessarily preclude such asymmetric load balancing procedures do not necessarily preclude such asymmetric
access bandwidth distribution among the PEs providing redundancy, it access bandwidth distribution among the PEs providing redundancy, it
may result in unexpected traffic loss due to congestion in the access may result in unexpected traffic loss due to congestion in the access
interface towards CE. This traffic loss is due to the fact that PE1 interface towards CE. This traffic loss is due to the fact that PE1
and PE2 will continue to attract equal amount of CE1 destined traffic and PE2 will continue to be treated as equal cost paths at remote
from remote PEs, even when PE2 only has half the bandwidth to CE1 as PEs, and as a result may attract approximately equal amount of CE1
destined traffic, even when PE2 only has half the bandwidth to CE1 as
PE1. This may lead to congestion and traffic loss on the PE2-CE1 PE1. This may lead to congestion and traffic loss on the PE2-CE1
link. If bandwidth distribution to CE1 across PE1 and PE2 is 2:1, link. If bandwidth distribution to CE1 across PE1 and PE2 is 2:1,
traffic from remote hosts MUST also be load-balanced across PE1 and traffic from remote hosts must also be load balanced across PE1 and
PE2 in 2:1 manner. PE2 in 2:1 manner.
2.2. PE CE Link Failures 2.2. PE-CE Link Failures
More importantly, unequal PE-CE bandwidth distribution described More importantly, unequal PE-CE bandwidth distribution described
above may occur during regular operation following a link failure, above may occur during regular operation following a link failure,
even when PE-CE links were provisioned to provide equal bandwidth even when PE-CE links were provisioned to provide equal bandwidth
distribution across multi-homing PEs. distribution across multi-homing PEs.
+------------------------+ +------------------------+
| Underlay Network Fabric| | Underlay Network Fabric|
+------------------------+ +------------------------+
skipping to change at page 5, line 38 skipping to change at page 5, line 50
\\ ESI-1 // \\ ESI-1 //
\\ /X \\ /X
+\\---//+ +\\---//+
| \\ // | | \\ // |
+---+---+ +---+---+
| |
CE1 CE1
Figure 2 Figure 2
Consider a CE1 that is multi-homed to PE1 and PE2 via a link bundle Consider a CE1 that is multi-homed to PE1 and PE2 via a LAG with two
with two member links to each PE. On a PE2-CE1 physical link member links to each PE. On a PE2-CE1 physical link failure, LAG
failure, link bundle represented by an Ethernet Segment ESI-1 on PE2 represented by an Ethernet Segment ESI-1 on PE2 stays up, however,
stays up, however, it's bandwidth is cut in half. With existing ECMP its bandwidth is cut in half. With existing ECMP procedures, both
procedures, both PE1 and PE2 will continue to attract equal amount of PE1 and PE2 may continue to attract equal amount of traffic from
traffic from remote PEs, even when PE1 has double the bandwidth to remote PEs, even when PE1 has double the bandwidth to CE1. If
CE1. If bandwidth distribution to CE1 across PE1 and PE2 is 2:1, bandwidth distribution to CE1 across PE1 and PE2 is 2:1, traffic from
traffic from remote hosts MUST also be load-balanced across PE1 and remote hosts must also be load balanced across PE1 and PE2 in 2:1
PE2 in 2:1 manner to avoid unexpected congestion and traffic loss on manner to avoid unexpected congestion and traffic loss on PE2-CE1
PE2-CE1 links within the LAG. links within the LAG. As an alternative, min-link on LAGs is
sometimes used to bring down the LAG interface on member link
failures. This however results in loss of available bandwidth in the
network, and is not ideal.
2.3. Design Requirement 2.3. Design Requirement
+-----------------------+ +-----------------------+
|Underlay Network Fabric| |Underlay Network Fabric|
+-----------------------+ +-----------------------+
+-----+ +-----+ +-----+ +-----+ +-----+ +-----+ +-----+ +-----+
| PE1 | | PE2 | ..... | PEx | | PEn | | PE1 | | PE2 | ..... | PEx | | PEn |
+-----+ +-----+ +-----+ +-----+ +-----+ +-----+ +-----+ +-----+
skipping to change at page 6, line 26 skipping to change at page 6, line 37
\ \ // // \ \ // //
+-\-------\-----------//--------//-+ +-\-------\-----------//--------//-+
| \ \ ESI-1 // // | | \ \ ESI-1 // // |
+----------------------------------+ +----------------------------------+
| |
CE CE
Figure 3 Figure 3
To generalize, if total link bandwidth to a CE is distributed across To generalize, if total link bandwidth to a CE is distributed across
"n" multi-homing PEs, with Lx being the number of links / bandwidth "n" multi-homing PEs, with Lx being the total bandwidth to PEx across
to PEx, traffic from remote PEs to this CE MUST be load-balanced all links, traffic from remote PEs to this CE must be load balanced
unequally across [PE1, PE2, ....., PEn] such that, fraction of total unequally across [PE1, PE2, ....., PEn] such that, fraction of total
unicast and BUM flows destined for CE that are serviced by PEx is: unicast and BUM flows destined for CE that are serviced by PEx is:
Lx / [L1+L2+.....+Ln] Lx / [L1+L2+.....+Ln]
Solution proposed below includes extensions to EVPN procedures to The solution proposed below includes extensions to EVPN procedures to
achieve the above. achieve the above.
2.4. 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
BCP14 [RFC2119] [RFC8174] when, and only when, they appear in all
capitals, as shown here.
"LOCAL PE" in the context of an ESI refers to a provider edge switch
OR router that physically hosts the ESI.
"REMOTE PE" in the context of an ESI refers to a provider edge switch
OR router in an EVPN overlay, who's overlay reachability to the ESI
is via the LOCAL PE.
3. Solution Overview 3. Solution Overview
In order to achieve weighted load balancing for overlay unicast In order to achieve weighted load balancing for overlay unicast
traffic, Ethernet A-D per-ES route (EVPN Route Type 1) is leveraged traffic, Ethernet A-D per-ES route (EVPN Route Type 1) is leveraged
to signal the Ethernet Segment bandwidth to remote PEs. Using to signal the Ethernet Segment bandwidth to remote PEs. Using
Ethernet A-D per-ES route to signal the Ethernet Segment bandwidth Ethernet A-D per-ES route to signal the Ethernet Segment bandwidth
provides a mechanism to be able to react to changes in access provides a mechanism to be able to react to changes in access
bandwidth in a service and host independent manner. Remote PEs bandwidth in a service and host independent manner. Remote PEs
computing the MAC path-lists based on global and aliasing Ethernet computing the MAC path-lists based on global and aliasing Ethernet
A-D routes now have the ability to setup weighted load-balancing A-D routes now have the ability to setup weighted load balancing
path-lists based on the ESI access bandwidth received from each PE path-lists based on the ESI access bandwidth received from each PE
that the ESI is multi-homed to. If Ethernet A-D per-ES route is also that the ESI is multi-homed to. If Ethernet A-D per-ES route is also
leveraged for IP path-list computation, as per [EVPN-IP-ALIASING], it leveraged for IP path-list computation, as per [EVPN-IP-ALIASING], it
also provides a method to do weighted load-balancing for IP routed also provides a method to do weighted load balancing for IP routed
traffic. traffic.
In order to achieve weighted load-balancing of overlay BUM traffic, In order to achieve weighted load balancing of overlay BUM traffic,
EVPN ES route (Route Type 4) is leveraged to signal the ESI bandwidth EVPN ES route (Route Type 4) is leveraged to signal the ESI bandwidth
to PEs within an ESI's redundancy group to influence per-service DF to PEs within an ESI's redundancy group to influence per-service DF
election. PEs in an ESI redundancy group now have the ability to do election. PEs in an ESI redundancy group now have the ability to do
service carving in proportion to each PE's relative ESI bandwidth. service carving in proportion to each PE's relative ESI bandwidth.
Procedures to accomplish this are described in greater detail next. Procedures to accomplish this are described in greater detail next.
4. Weighted Unicast Traffic Load-balancing 4. Weighted Unicast Traffic Load-balancing
4.1. LOCAL PE Behavior 4.1. Local PE Behavior
A PE that is part of an Ethernet Segment's redundancy group would A PE that is part of an Ethernet Segment's redundancy group would
advertise a additional "link bandwidth" EXT-COMM attribute with advertise an additional "link bandwidth" extended community attribute
Ethernet A-D per-ES route (EVPN Route Type 1), that represents total with Ethernet A-D per-ES route (EVPN Route Type 1), that represents
bandwidth of PE's physical links in an Ethernet Segment. BGP link total bandwidth of PE's physical links in an Ethernet Segment. BGP
bandwidth EXT-COMM defined in [BGP-LINK-BW] is re-used for this link bandwidth extended community defined in [BGP-LINK-BW] is re-used
purpose. for this purpose.
4.2. Link Bandwidth Extended Community 4.2. Link Bandwidth Extended Community
Link bandwidth extended community described in [BGP-LINK-BW] for Link bandwidth extended community described in [BGP-LINK-BW] for
layer 3 VPNs is re-used here to signal local ES link bandwidth to layer 3 VPNs is re-used here to signal local ES link bandwidth to
remote PEs. link-bandwidth extended community is however defined in remote PEs. link bandwidth extended community is however defined in
[BGP-LINK-BW] as optional non-transitive. In inter-AS scenarios, [BGP-LINK-BW] as optional non-transitive. In inter-AS scenarios,
link-bandwidth may need to be signaled to an eBGP neighbor along with link-bandwidth may need to be signaled to an eBGP neighbor along with
next-hop unchanged. It is work in progress with authors of [BGP- next-hop unchanged. It is work in progress with authors of [BGP-
LINK-BW] to allow for this attribute to be used as transitive in LINK-BW] to allow for this attribute to be used as transitive in
inter-AS scenarios. inter-AS scenarios.
4.3. REMOTE PE Behavior 4.3. Remote PE Behavior
A receiving PE should use per-ES link bandwidth attribute received A receiving PE SHOULD use per-ES link bandwidth attribute received
from each PE to compute a relative weight for each remote PE, per-ES, from each PE to compute a relative weight for each remote PE, per-ES,
as shown below. and then use this relative weight to compute a weighted path-list to
be used for load balancing, as opposed to using an ECMP path-list for
load balancing across the PE paths. PE Weight and resulting weighted
path-list computation at remote PEs is a local matter. An example
computation algorithm is shown below to illustrate the idea:
if, if,
L(x,y) : link bandwidth advertised by PE-x for ESI-y L(x,y) : link bandwidth advertised by PE-x for ESI-y
W(x,y) : normalized weight assigned to PE-x for ESI-y W(x,y) : normalized weight assigned to PE-x for ESI-y
H(y) : Highest Common Factor (HCF) of [L(1,y), L(2,y), ....., L(n,y)] H(y) : Highest Common Factor (HCF) of [L(1,y), L(2,y), ....., L(n,y)]
then, the normalized weight assigned to PE-x for ESI-y may be then, the normalized weight assigned to PE-x for ESI-y may be
computed as follows: computed as follows:
W(x,y) = L(x,y) / H(y) W(x,y) = L(x,y) / H(y)
For a MAC+IP route (EVPN Route Type 2) received with ESI-y, receiving For a MAC+IP route (EVPN Route Type 2) received with ESI-y, receiving
PE MUST compute MAC and IP forwarding path-list weighted by the above PE may compute MAC and IP forwarding path-list weighted by the above
normalized weights. normalized weights.
As an example, for a CE dual-homed to PE-1, PE-2, PE-3 via 2, 1, and As an example, for a CE dual-homed to PE-1, PE-2, PE-3 via 2, 1, and
1 GE physical links respectively, as part of a link bundle 1 GE physical links respectively, as part of a LAG represented by
represented by ESI-10: ESI-10:
L(1, 10) = 2000 Mbps L(1, 10) = 2000 Mbps
L(2, 10) = 1000 Mbps L(2, 10) = 1000 Mbps
L(3, 10) = 1000 Mbps L(3, 10) = 1000 Mbps
H(10) = 1000 H(10) = 1000
Normalized weights assigned to each PE for ESI-10 are as follows: Normalized weights assigned to each PE for ESI-10 are as follows:
W(1, 10) = 2000 / 1000 = 2. W(1, 10) = 2000 / 1000 = 2.
W(2, 10) = 1000 / 1000 = 1. W(2, 10) = 1000 / 1000 = 1.
W(3, 10) = 1000 / 1000 = 1. W(3, 10) = 1000 / 1000 = 1.
For a remote MAC+IP host route received with ESI-10, forwarding load- For a remote MAC+IP host route received with ESI-10, forwarding load
balancing path-list must now be computed as: [PE-1, PE-1, PE-2, PE-3] balancing path-list may now be computed as: [PE-1, PE-1, PE-2, PE-3]
instead of [PE-1, PE-2, PE-3]. This now results in load-balancing of instead of [PE-1, PE-2, PE-3]. This now results in load balancing of
all traffic destined for ESI-10 across the three multi-homing PEs in all traffic destined for ESI-10 across the three multi-homing PEs in
proportion to ESI-10 bandwidth at each PE. proportion to ESI-10 bandwidth at each PE.
Above weighted path-list computation MUST only be done for an ESI, IF Weighted path-list computation must only be done for an ESI if a link
a link bandwidth attribute is received from ALL of the PE's bandwidth attribute is received from all of the PE's advertising
advertising reachability to that ESI via Ethernet A-D per-ES Route reachability to that ESI via Ethernet A-D per-ES Route Type 1. In an
Type 1. In the event that link bandwidth attribute is not received unlikely event that link bandwidth attribute is not received from one
from one or more PEs, forwarding path-list would be computed using or more subset of PEs, forwarding path-list should be computed using
regular ECMP semantics. regular ECMP semantics. Note that a default weight cannot be assumed
for a PE that does not advertise its link bandwidth as the weight
attribute t be used in path-list computation is relative.
5. Weighted BUM Traffic Load-Sharing 5. Weighted BUM Traffic Load-Sharing
Optionally, load sharing of per-service DF role, weighted by Optionally, load sharing of per-service DF role, weighted by
individual PE's link-bandwidth share within a multi-homed ES may also individual PE's link-bandwidth share within a multi-homed ES may also
be achieved. be achieved.
In order to do that, a new DF Election Capability [RFC8584] called In order to do that, a new DF Election Capability [RFC8584] called
"BW" (Bandwidth Weighted DF Election) is defined. BW may be used "BW" (Bandwidth Weighted DF Election) is defined. BW MAY be used
along with some DF Election Types, as described in the following along with some DF Election Types, as described in the following
sections. sections.
5.1. The BW Capability in the DF Election Extended Community 5.1. The BW Capability in the DF Election Extended Community
[RFC8584] defines a new extended community for PEs within a [RFC8584] defines a new extended community for PEs within a
redundancy group to signal and agree on uniform DF Election Type and redundancy group to signal and agree on uniform DF Election Type and
Capabilities for each ES. This document requests a bit in the DF Capabilities for each ES. This document requests IANA for a bit in
Election extended community Bitmap: the DF Election extended community Bitmap:
Bit 28: BW (Bandwidth Weighted DF Election) Bit 28: BW (Bandwidth Weighted DF Election)
ES routes advertised with the BW bit set will indicate the desire of ES routes advertised with the BW bit set will indicate the desire of
the advertising PE to consider the link-bandwidth in the DF Election the advertising PE to consider the link-bandwidth in the DF Election
algorithm defined by the value in the "DF Type". algorithm defined by the value in the "DF Type".
As per [RFC8584], all the PEs in the ES MUST advertise the same As per [RFC8584], all the PEs in the ES MUST advertise the same
Capabilities and DF Type, otherwise the PEs will fall back to Default Capabilities and DF Type, otherwise the PEs will fall back to Default
[RFC7432] DF Election procedure. [RFC7432] DF Election procedure.
skipping to change at page 10, line 8 skipping to change at page 10, line 8
o Type 4: HRW per-multicast flow DF Election, as in [EVPN-PER-MCAST- o Type 4: HRW per-multicast flow DF Election, as in [EVPN-PER-MCAST-
FLOW-DF] FLOW-DF]
The following sections describe how the DF Election procedures are The following sections describe how the DF Election procedures are
modified for the above DF Types when the BW Capability is used. modified for the above DF Types when the BW Capability is used.
5.2. BW Capability and Default DF Election algorithm 5.2. BW Capability and Default DF Election algorithm
When all the PEs in the Ethernet Segment (ES) agree to use the BW When all the PEs in the Ethernet Segment (ES) agree to use the BW
Capability with DF Type 0, the Default DF Election procedure is Capability with DF Type 0, the Default DF Election procedure as
modified as follows: defined in [RFC7432] is modified as follows:
o Each PE advertises a "Link Bandwidth" EXT-COMM attribute along o Each PE advertises a "Link Bandwidth" extended community attribute
with the ES route to signal the PE-CE link bandwidth (LBW) for the along with the ES route to signal the PE-CE link bandwidth (LBW)
ES. for the ES.
o A receiving PE MUST use the ES link bandwidth attribute received o A receiving PE MUST use the ES link bandwidth attribute received
from each PE to compute a relative weight for each remote PE. from each PE to compute a relative weight for each remote PE.
o The DF Election procedure MUST now use this weighted list of PEs o The DF Election procedure MUST now use this weighted list of PEs
to compute the per-VLAN Designated Forwarder, such that the DF to compute the per-VLAN Designated Forwarder, such that the DF
role is distributed in proportion to this normalized weight. role is distributed in proportion to this normalized weight. As a
result, a single PE may have multiple ordinals in the DF candidate
PE list and 'N' used in (V mode N) operation as defined in
[RFC7432] is modified to be total number of ordinals instead of
being total number of PEs.
Considering the same example as in Section 3, the candidate PE list Considering the same example as in Section 3, the candidate PE list
for DF election is: for DF election is:
[PE-1, PE-1, PE-2, PE-3]. [PE-1, PE-1, PE-2, PE-3].
The DF for a given VLAN-a on ES-10 is now computed as (VLAN-a % 4). The DF for a given VLAN-a on ES-10 is now computed as (VLAN-a % 4).
This would result in the DF role being distributed across PE1, PE2, This would result in the DF role being distributed across PE1, PE2,
and PE3 in portion to each PE's normalized weight for ES-10. and PE3 in portion to each PE's normalized weight for ES-10.
skipping to change at page 11, line 32 skipping to change at page 11, line 36
Note that the bandwidth increment must always be an integer, Note that the bandwidth increment must always be an integer,
including, in an unlikely scenario of a PE's link bandwidth not being including, in an unlikely scenario of a PE's link bandwidth not being
an exact multiple of L(min). If it computes to a non-integer value an exact multiple of L(min). If it computes to a non-integer value
(including as a result of link failure), it MUST be rounded down to (including as a result of link failure), it MUST be rounded down to
an integer. an integer.
5.3.2. HRW Hash Computations with BW Increment 5.3.2. HRW Hash Computations with BW Increment
HRW algorithm as described in [RFC8584] and in [EVPN-PER-MCAST-FLOW- HRW algorithm as described in [RFC8584] and in [EVPN-PER-MCAST-FLOW-
DF] compute a random hash value (referred to as affinity here) for DF] computes a random hash value for each PE(i), where, (0 < i <= N),
each PE(i), where, (0 < i <= N), PE(i) is the PE at ordinal i, and PE(i) is the PE at ordinal i, and Address(i) is the IP address of
Address(i) is the IP address of PE at ordinal i. PE(i).
For 'N' PEs sharing an Ethernet segment, this results in 'N' For 'N' PEs sharing an Ethernet segment, this results in 'N'
candidate hash computations. PE that has the highest hash value is candidate hash computations. The PE that has the highest hash value
selected as the DF. is selected as the DF.
Affinity computation for each PE(i) is extended to be computed one We refer to this hash value as "affinity" in this document. Hash or
per-bandwidth increment associated with PE(i) instead of a single affinity computation for each PE(i) is extended to be computed one
per bandwidth increment associated with PE(i) instead of a single
affinity computation per PE(i). affinity computation per PE(i).
PE(i) with b(i) = j, results in j affinity computations: PE(i) with b(i) = j, results in j affinity computations:
affinity(i, x), where 1 < x <= j affinity(i, x), where 1 < x <= j
This essentially results in number of candidate HRW hash computations This essentially results in number of candidate HRW hash computations
for each PE that is directly proportional to that PE's relative for each PE that is directly proportional to that PE's relative
bandwidth within an ES and hence gives PE(i) a probability of being bandwidth within an ES and hence gives PE(i) a probability of being
DF in proportion to it's relative bandwidth within an ES. DF in proportion to it's relative bandwidth within an ES.
As an example, consider an ES that is multi-homed to two PEs, PE1 and As an example, consider an ES that is multi-homed to two PEs, PE1 and
PE2, with equal bandwidth distribution across PE1 and PE2. This PE2, with equal bandwidth distribution across PE1 and PE2. This
would result in a total of two candidate hash computations: would result in a total of two candidate hash computations:
affinity(PE1, 1) affinity(PE1, 1)
skipping to change at page 12, line 44 skipping to change at page 13, line 5
affinity(S,G,V, ESI, Address(i,j)) = affinity(S,G,V, ESI, Address(i,j)) =
(1103515245.((1103515245.Address(i).j + 12345) XOR (1103515245.((1103515245.Address(i).j + 12345) XOR
D(S,G,V,ESI))+12345) (mod 2^31) D(S,G,V,ESI))+12345) (mod 2^31)
affinity or random function specified in [RFC8584] MAY be extended as affinity or random function specified in [RFC8584] MAY be extended as
follows to incorporate bandwidth increment j: follows to incorporate bandwidth increment j:
affinity(v, Es, Address(i,j)) = (1103515245((1103515245.Address(i).j affinity(v, Es, Address(i,j)) = (1103515245((1103515245.Address(i).j
+ 12345) XOR D(v,Es))+12345)(mod 2^31) + 12345) XOR D(v,Es))+12345)(mod 2^31)
5.3.3. Cost-Benefit Tradeoff on Link Failures
While incorporating link bandwidth into the DF election process
provides optimal BUM traffic distribution across the ES links, it
also implies that affinity values for a given PE are re-computed, and
DF elections are re-adjusted on changes to that PE's bandwidth
increment that might result from link failures or link additions. If
the operator does not wish to have this level of churn in their DF
election, then they should not advertise the BW capability. Not
advertising BW capability may result in less than optimal BUM traffic
distribution while still retaining the ability to allow a remote
ingress PE to do weighted ECMP for its unicast traffic to a set of
multi-homed PEs, as described in section 3.2.
Same also applies to use of BW capability with service carving (DF
Type 0), as specified in section 4.2.
5.4. BW Capability and Weighted HRW DF Election algorithm (Type TBD) 5.4. BW Capability and Weighted HRW DF Election algorithm (Type TBD)
Use of BW capability together with HRW DF election algorithm Use of BW capability together with HRW DF election algorithm
described in the previous section has a few limitations: described in the previous section has a few limitations:
o While in most scenarios a change in BW for a given PE results in o While in most scenarios a change in BW for a given PE results in
re-assigment of DF roles from or to that PE, in certain scenarios, re-assigment of DF roles from or to that PE, in certain scenarios,
a change in PE BW can result in complete re-assignment of DF a change in PE BW can result in complete re-assignment of DF
roles. roles.
o If BW advertised from a set of PEs does not have a good least o If BW advertised from a set of PEs does not have a good least
common multiple, the BW set may result in a high BW increment for common multiple, the BW set may result in a high BW increment for
each PE, and hence, may result in higher order of complexity. each PE, and hence, may result in higher order of complexity.
[WEIGHTED-HRW] document describes an alternate DF election algorithm [RFC8584] describes an alternate DF election algorithm that uses a
that uses a weighted score function that is minimally disruptive such weighted score function that is minimally disruptive such that it
that it minimizes the probability of complete re-assignment of DF minimizes the probability of complete re-assignment of DF roles in a
roles in a BW change scenario. It also does not require multiple BW BW change scenario. It also does not require multiple BW increment
increment based computations. based computations.
Instead of computing BW increment and an HRW hash for each [PE, BW Instead of computing BW increment and an HRW hash for each [PE, BW
increment], a single weighted score is computed for each PE using the increment], a single weighted score is computed for each PE using the
proposed score function with absolute BW advertised by each PE as its proposed score function with absolute BW advertised by each PE as its
weight value. weight value.
As described in section 4 of [WEIGHTED-HRW], a HRW hash computation As described in section 4 of [RFC8584], a HRW hash computation for
for each PE is converted to a weighted score as follows: each PE is converted to a weighted score as follows:
Score(Oi, Sj) = -wi/log(Hash(Oi, Sj)/Hmax); where Hmax is the maximum Score(Oi, Sj) = -wi/log(Hash(Oi, Sj)/Hmax); where Hmax is the maximum
hash value. hash value.
Oi is object being assigned, for e.g., a vlan-id in this case; Oi is object being assigned, for e.g., a vlan-id in this case;
Sj is the server, for e.g., a PE IP address in this case; Sj is the server, for e.g., a PE IP address in this case;
wi is the weight, for e.g., BW capability in this case; wi is the weight, for e.g., BW capability in this case;
skipping to change at page 14, line 30 skipping to change at page 14, line 20
[Pref=500,DP=1, LBW=2000] in PE2, PE2 would be elected due to the [Pref=500,DP=1, LBW=2000] in PE2, PE2 would be elected due to the
DP bit. DP bit.
o If vES1 parameters were [Pref=500,DP=0,LBW=1000] in PE1 and o If vES1 parameters were [Pref=500,DP=0,LBW=1000] in PE1 and
[Pref=500,DP=0, LBW=2000] in PE2, PE2 would be elected due to a [Pref=500,DP=0, LBW=2000] in PE2, PE2 would be elected due to a
higher LBW, even if PE1's IP address is lower. higher LBW, even if PE1's IP address is lower.
o The LBW exchanged value has no impact on the Non-Revertive option o The LBW exchanged value has no impact on the Non-Revertive option
described in [EVPN-DF-PREF]. described in [EVPN-DF-PREF].
6. Real-time Available Bandwidth 6. Cost-Benefit Tradeoff on Link Failures
While incorporating link bandwidth into the DF election process
provides optimal BUM traffic distribution across the ES links, it
also implies that DF elections are re-adjusted on link failures or
bandwidth changes. If the operator does not wish to have this level
of churn in their DF election, then they should not advertise the BW
capability. Not advertising BW capability may result in less than
optimal BUM traffic distribution while still retaining the ability to
allow a remote ingress PE to do weighted ECMP for its unicast traffic
to a set of multi-homed PEs.
7. Real-time Available Bandwidth
PE-CE link bandwidth availability may sometimes vary in real-time PE-CE link bandwidth availability may sometimes vary in real-time
disproportionately across PE_CE links within a multi-homed ESI due to disproportionately across PE-CE links within a multi-homed ESI due to
various factors such as flow based hashing combined with fat flows various factors such as flow based hashing combined with fat flows
and unbalanced hashing. Reacting to real-time available bandwidth is and unbalanced hashing. Reacting to real-time available bandwidth is
at this time outside the scope of this document. Procedures at this time outside the scope of this document. Procedures
described in this document are strictly based on static link described in this document are strictly based on static link
bandwidth parameter. bandwidth parameter.
7. Routed EVPN Overlay 8. Routed EVPN Overlay
An additional use case is possible, such that traffic to an end host An additional use case is possible, such that traffic to an end host
in the overlay is always IP routed. In a purely routed overlay such in the overlay is always IP routed. In a purely routed overlay such
as this: as this:
o A host MAC is never advertised in EVPN overlay control plane o A host MAC is never advertised in EVPN overlay control plane.
o Host /32 or /128 IP reachability is distributed across the overlay o Host /32 or /128 IP reachability is distributed across the overlay
via EVPN route type 5 (RT-5) along with a zero or non-zero ESI via EVPN route type 5 (RT-5) along with a zero or non-zero ESI.
o An overlay IP subnet may still be stretched across the underlay o An overlay IP subnet may still be stretched across the underlay
fabric, however, intra-subnet traffic across the stretched overlay fabric, however, intra-subnet traffic across the stretched overlay
is never bridged is never bridged.
o Both inter-subnet and intra-subnet traffic, in the overlay is IP o Both inter-subnet and intra-subnet traffic, in the overlay is IP
routed at the EVPN GW. routed at the EVPN GW.
Please refer to [RFC 7814] for more details. Please refer to [RFC7814] for more details.
Weighted multi-path procedure described in this document may be used Weighted multi-path procedure described in this document may be used
together with procedures described in [EVPN-IP-ALIASING] for this use together with procedures described in [EVPN-IP-ALIASING] for this use
case. Ethernet A-D per-ES route advertised with Layer 3 VRF RTs case. Ethernet A-D per-ES route advertised with Layer 3 VRF RTs
would be used to signal ES link bandwidth attribute instead of the would be used to signal ES link bandwidth attribute instead of the
Ethernet A-D per-ES route with Layer 2 VRF RTs. All other procedures Ethernet A-D per-ES route with Layer 2 VRF RTs. All other procedures
described earlier in this document would apply as is. described earlier in this document would apply as is.
If [EVPN-IP-ALIASING] is not used for routed fast convergence, link If [EVPN-IP-ALIASING] is not used for routed fast convergence, link
bandwidth attribute may still be advertised with IP routes (RT-5) to bandwidth attribute may still be advertised with IP routes (RT-5) to
achieve PE-CE link bandwidth based load-balancing as described in achieve PE-CE link bandwidth based load balancing as described in
this document. In the absence of [EVPN-IP-ALIASING], re-balancing of this document. In the absence of [EVPN-IP-ALIASING], re-balancing of
traffic following changes in PE-CE link bandwidth will require all IP traffic following changes in PE-CE link bandwidth will require all IP
routes from that CE to be re-advertised in a prefix dependent manner. routes from that CE to be re-advertised in a prefix dependent manner.
8. EVPN-IRB Multi-homing with non-EVPN routing 9. EVPN-IRB Multi-homing With Non-EVPN routing
EVPN-LAG based multi-homing on an IRB gateway may also be deployed EVPN-LAG based multi-homing on an IRB gateway may also be deployed
together with non-EVPN routing, such as global routing or an L3VPN together with non-EVPN routing, such as global routing or an L3VPN
routing control plane. Key property that differentiates this set of routing control plane. Key property that differentiates this set of
use cases from EVPN IRB use cases discussed earlier is that EVPN use cases from EVPN IRB use cases discussed earlier is that EVPN
control plane is used only to enable LAG interface based multi-homing control plane is used only to enable LAG interface based multi-homing
and NOT as an overlay VPN control plane. EVPN control plane in this and NOT as an overlay VPN control plane. EVPN control plane in this
case enables: case enables:
o DF election via EVPN RT-4 based procedures described in [RFC7432] o DF election via EVPN RT-4 based procedures described in [RFC7432]
o LOCAL MAC sync across multi-homing PEs via EVPN RT-2 o Local MAC sync across multi-homing PEs via EVPN RT-2
o LOCAL ARP and ND sync across multi-homing PEs via EVPN RT-2 o Local ARP and ND sync across multi-homing PEs via EVPN RT-2
Applicability of weighted ECMP procedures proposed in this document Applicability of weighted ECMP procedures proposed in this document
to these set of use cases is an area of further consideration. to these set of use cases is an area of further consideration.
9. Operational Considerations 10. Operational Considerations
None None
10. Security Considerations 11. Security Considerations
This document raises no new security issues for EVPN. This document raises no new security issues for EVPN.
11. Acknowledgements 12. IANA Considerations
[RFC8584] defines a new extended community for PEs within a
redundancy group to signal and agree on uniform DF Election Type and
Capabilities for each ES. This document requests IANA for a bit in
the DF Election extended community Bitmap:
Bit 28: BW (Bandwidth Weighted DF Election)
13. Acknowledgements
Authors would like to thank Satya Mohanty for valuable review and Authors would like to thank Satya Mohanty for valuable review and
inputs with respect to HRW and weighted HRW algorithm refinements inputs with respect to HRW and weighted HRW algorithm refinements
proposed in this document. proposed in this document.
12. Contributors 14. Contributors
Satya Ranjan Mohanty Satya Ranjan Mohanty
Cisco Systems Cisco Systems
US US
Email: satyamoh@cisco.com Email: satyamoh@cisco.com
13. Normative References 15. Normative References
[BGP-LINK-BW] [BGP-LINK-BW]
Mohapatra, P. and R. Fernando, "BGP Link Bandwidth Mohapatra, P. and R. Fernando, "BGP Link Bandwidth
Extended Community", draft-ietf-idr-link-bandwidth-07 Extended Community", draft-ietf-idr-link-bandwidth-07
(work in progress), March 2019. (work in progress), March 2019.
[EVPN-DF-PREF] [EVPN-DF-PREF]
Rabadan, J., Sathappan, S., Przygienda, T., Lin, W., Rabadan, J., Sathappan, S., Przygienda, T., Lin, W.,
Drake, J., Sajassi, A., Mohanty, S., and , "Preference- Drake, J., Sajassi, A., Mohanty, S., and , "Preference-
based EVPN DF Election", draft-ietf-bess-evpn-pref-df-05 based EVPN DF Election", draft-ietf-bess-evpn-pref-df-05
skipping to change at page 17, line 10 skipping to change at page 17, line 21
[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>.
[RFC7432] Sajassi, A., Ed., Aggarwal, R., Bitar, N., Isaac, A., [RFC7432] Sajassi, A., Ed., Aggarwal, R., Bitar, N., Isaac, A.,
Uttaro, J., Drake, J., and W. Henderickx, "BGP MPLS-Based Uttaro, J., Drake, J., and W. Henderickx, "BGP MPLS-Based
Ethernet VPN", RFC 7432, DOI 10.17487/RFC7432, February Ethernet VPN", RFC 7432, DOI 10.17487/RFC7432, February
2015, <https://www.rfc-editor.org/info/rfc7432>. 2015, <https://www.rfc-editor.org/info/rfc7432>.
[RFC7814] Xu, X., Jacquenet, C., Raszuk, R., Boyes, T., and B. Fee,
"Virtual Subnet: A BGP/MPLS IP VPN-Based Subnet Extension
Solution", RFC 7814, DOI 10.17487/RFC7814, March 2016,
<https://tools.ietf.org/html/rfc7814>.
[RFC8584] Rabadan, J., Ed., Mohanty, R., Sajassi, N., Drake, A., [RFC8584] Rabadan, J., Ed., Mohanty, R., Sajassi, N., Drake, A.,
Nagaraj, K., and S. Sathappan, "BGP MPLS-Based Ethernet Nagaraj, K., and S. Sathappan, "Framework for Ethernet VPN
VPN", RFC 8584, DOI 10.17487/RFC8584, April 2019, Designated Forwarder Election Extensibility", RFC 8584,
DOI 10.17487/RFC8584, April 2019,
<https://www.rfc-editor.org/info/rfc8584>. <https://www.rfc-editor.org/info/rfc8584>.
Authors' Addresses Authors' Addresses
Neeraj Malhotra (editor) Neeraj Malhotra (editor)
Cisco Systems Cisco Systems
170 W. Tasman Drive 170 W. Tasman Drive
San Jose, CA 95134 San Jose, CA 95134
USA USA
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