Issues With EVPN and Anycast

Feb 10, 2025
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Setup Overview:
- Two virtual routers that run VyOS setup on Dell servers with an Anycast gateway configured between them that allows all other VMs to use either one as their default gateway.
- The virtual routers run OSPF and share routes with two upstream Mikrotiks, which then share routes with a core that shares routes with the rest of the Internet.
- EVPN SDN configured on both nodes (hosting the virtual routers).

Currently with how this is setup, we can reach the internet from any VM on either node behind either virtual router. We know the anycast gateway is working because disabling one of the virtual routers still allows us to get out from VMs behind the virtual routers.

The main issue we are seeing is that certain actions (e.g. VM file system updates) are almost impossible when using this Anycast setup as the speeds they get out to the Internet are sometimes as low as 20Mb with latency of 300ms+. Disabling one of the virtual routers resolves this immediately.

We don't believe it is anything to do with MTU as we have tested multiple different values with the same issue and as mentioned connectivity to the Internet basically works fine (e.g. we can ping 8.8.8.8).

Please let me know what information is required.