topic Re: IP load sharing on MLXE in Data Center (MLX & CER/CES)

IP load sharing on MLXE

pbradford — Wed, 03 Jul 2019 19:40:10 GMT

So here's the setup. We have an MLXe with 2 LAGs to a Cisco CMTS (cbr). these two are OSPF neighbors. The CMTS announces it's routes via iBGP to a Route Reflector elsewhere in the network.

what we're seeing is that traffic towards the CMTS is taking 1 LAG. Traffic out from the CMTS is load balanced fine it's just the traffic towards the CMTS that is lopsided. Is there a way on the MLXe to check the load sharing algorithm? Any ideas why it might pick one lag over the other with each being exactly the same OSPF cost?

Thanks

Re: IP load sharing on MLXE

Samantha_R_Newm — Thu, 18 Jul 2019 00:25:04 GMT

I believe this is the same question you asked in the ticket you opened with us that I helped with.

For the community it was due to Multipath not being enabled for BGP. BGP (I or E) will only ever use 1 path by default. By configuring Multipath for BGP this allowed for the load sharing to take place between two equal cost paths.

Re: IP load sharing on MLXE

pbradford — Thu, 18 Jul 2019 00:34:38 GMT

config snippet I was missing:

router bgp
address-family ipv4 unicast
maximum-paths 8

Thanks Samantha!