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  1. Fast Datapath Product
  2. FDP-3067

[EVPN] Support All-Active Layer-2 multihoming ("ECMP").

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    • Icon: Epic Epic
    • Resolution: Unresolved
    • Icon: Major Major
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    • OVN
    • None
    • [EVPN] Support All-Active Layer-2 multihoming ("ECMP").
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      Please mark each item below with ( / ) if completed or ( x ) if incomplete:

      ( ) The acceptance criteria defined below are met.

      Given an OVN EVPN deployment where a remote MAC address is reachable via multiple VTEPs,
      When layer-2 traffic is sent to that MAC address,
      Then OVN distributes the traffic across all available VTEP paths using ECMP, and dynamically updates the forwarding when paths are added or removed.

      ( ) The epics work is available in a downstream build (nightly/async or other)

      ( ) Test coverage is available in downstream CI if applicable

      ( ) All cards under the epic have been moved to Done

      ( ) Failed Test Plans have bugs added as children to the epic/feature.

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      Please mark each item below with ( / ) if completed or ( x ) if incomplete: ( ) The acceptance criteria defined below are met. Given an OVN EVPN deployment where a remote MAC address is reachable via multiple VTEPs, When layer-2 traffic is sent to that MAC address, Then OVN distributes the traffic across all available VTEP paths using ECMP, and dynamically updates the forwarding when paths are added or removed. ( ) The epics work is available in a downstream build (nightly/async or other) ( ) Test coverage is available in downstream CI if applicable ( ) All cards under the epic have been moved to Done ( ) Failed Test Plans have bugs added as children to the epic/feature.
    • FDP-2753 - OVN-Kubernetes native BGP convergence
    • rhel-9
    • None
    • FDP-2753OVN-Kubernetes native BGP convergence
    • rhel-net-ovn
    • 100% To Do, 0% In Progress, 0% Done
    • ssg_networking

      This epic tracks all the effort needed to deliver the solution related to the feature request described below.

      What's the feature?

      Currently OVN's L2 EVPN integration doesn't support externally learned FDB records that
      are reachable through multiple VTEPs (multi-homed / ECMP). ovn-controller monitors the L2 VRF linux bridge FDB table but only installs records that are reachable through a single remote VTEP.

      Why is it needed?

      In multi-homed EVPN deployments (with some of the L2 addresses reachable at the same cost) it's important that other parts of the L2 EVPN domain can reach the multi-homed workloads on all paths, enabling load sharing across paths.
       

      Who will benefit? 

      Users that care about All-Active Layer-2 multihoming (ECMP) for EVPN, i.e., ovn-kubernetes, OpenStack.

      A sample configuration is available through the following script:
      https://github.com/dceara/ovn/blob/5fa75935c60c01d47291253572ab587ae09b1e33/tutorial/bgp/setup-l2-multihoming.sh

      This simulates the following topology:

                     +---- evpn-host2  ---+
               |                    |
evpn-host1 ----+                    +--- simulated-multi-homed-workloads
               |                    |
               +---- evpn-host3  ---+

      With BGP EVPN sessions between host1-host2 and host1-host3. Host1 learns the multi-homed FDBs via both other EVPN speakers and installs FDB entries in the kernel in the following form:

      # Check "ECMP" FDB on host1:
podman exec $h1 bridge fdb show static | grep 00:00:33:22:11:10
00:00:33:22:11:10 dev vxlan-10 vlan 1 extern_learn master br-10 
00:00:33:22:11:10 dev vxlan-10 extern_learn master br-10 
00:00:33:22:11:10 dev vxlan-10 nhid 536870913 self extern_learn

# Check "ECMP" nexthops on host1:
$ podman exec $h1 ip nexthop
id 268435458 via 20.0.0.2 scope link fdb
id 268435460 via 20.0.0.3 scope link fdb
id 536870913 group 268435458/268435460 fdb
id 536870915 group 268435458/268435460 fdb

              ovnteam@redhat.com OVN Team
              dceara@redhat.com Dumitru Ceara
              OVN QE OVN QE
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                Created:
                Updated: