NXOS EVPN iBGP to eBGP not propagated

[Vainius Dangovas]

Hi,

Wanted to share a strange scenario encountered in the wild. Maybe someone will find it useful.
Tested on NX-OS v9.3.9

Topology:
Router <- iBGP -> Nexus1 <- eBGP -> Nexus2

iBGP session on Nexus1 is AF IPv4 in VRF-A.
eBGP session between Nexus1 and Nexus2 is AF EVPN.

Routes, announced by Router to Nexus1 are learnt and in VRF RIB/FIB. Also in VPNv4 table, but not in EVPN table.

This also means that the route is not propagated over EVPN to Nexus 2.

Somehow this brakes iBGP to eBGP automatic announcement rule.

[Vainius Dangovas]

Found a workaround for this situation.

On Nexus1, in the context of BGP VRF setting `local-as` and reconfiguration of BGP peer AS on Router helps. After that Nexus1 thinks that it learnt routes from an eBGP peer and successfully exports it to BGP EVPN L2VPN table. From there on the routes are propagated to other EVPN peers.