02-28-2025 04:13 AM - edited 02-28-2025 06:41 AM
Troubleshooting a routing issue I've just discovered that the local preference isn't used for forwarding decisions when ECMP is enabled. Has anyone seen this before? I'm about to log a support case, but I thought I'd ask here in tandem.
What I see is that the inbound route map sets the local-preference, and ECMP then ignores this and uses all received prefixes as if they're equal. The peers are internal ebgp peers. I would have expected ECMP to consider the local preference set by the route map.
`show advanced-routing bgp filters route-map logical-router default ipv4 name <ROUTE-MAP>` shows the set local preference for each processed prefix.
`show advanced-routing bgp loc-rib-detail prefix <CIDR>` shows the received community, but the local preference is 0.
`show advanced-routing bgp route logical-router default afi ipv4` shows the BGP table, also with a local preference of 0.
03-07-2025 11:22 AM
If anyone else comes across the same behaviour, make sure to turn off graceful shutdown under logical router >> BGP >> General >> Options
02-28-2025 05:45 AM
I've verified that as-path prepending on the (remote) bgp peer works as expected for what I'm trying to do. I'll update here if support comes back with something useful.
Platform is a PA-3410 running 11.1.4(h9)
03-07-2025 11:22 AM
If anyone else comes across the same behaviour, make sure to turn off graceful shutdown under logical router >> BGP >> General >> Options
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