ECMP in overlay supported?

  • 25 April 2018
  • 3 replies

I am building an environment with symmetric vxlan routing. it consists of two spine devices and 10 14 MLAG TOR pairs. There are also two border devices connected to the spine switces. These border switches are not in an MLAG pair at this moment. Each border router has a bgp peering within a vrf towards a Cisco distribution router. These Cisco routers inject a default route into vrf. Border routers inject them in the BGP EVPN address familly. The routes are imported into the correct routing table at the tors. I noticed that when both routes are considered equal by the tor traffic is not forwarded out of the fabric. When I shut on of the BGP neighbours on the border router I am able to connect to the outside world of the fabric. When I use as path prepending on the border traffic is also able to reach the outside world.

Is ECMP supported in the overlay or should I configure my border devices as an mlag pair and route the traffic to the clag anycast ip in stead.


3 replies

Userlevel 1
ECMP across the EVPN overlay is not available in the 3.5.3 release, but it is planned for a future release.

For a release timeline, please contact your Cumulus Networks account team.
hi Mark,

could be you please clarify what is "ECMP across the EVPN overlay", bgp add-path?

@Eelco Nieuwstad1, do you mind dump the route on both source tor and border ( for given vrf ), I am interested in this traffic lost issue,
Userlevel 1
@Eric Dong
sorry for the delayed response, this feature is tracked internally by FR-765.