Cilium BGP and using FRR for node connectivity

Dual-homed servers use IP-unnumbered physical interfaces. A dedicated dummy interface (not lo) is assigned to each server as its IPv4 node address. FRR runs between the servers and the ToR switches to provide node-level connectivity, advertising the server’s node IP (dummy interface address) and receiving the default route from the ToRs.
Using a bond interface between ToRs can also be used for redundancy and failover for server connectivity. You may also configure Layer 3 interfaces. The main issue is about node identity and service continuity during the failure of a single link. Using a bond interface or a dummy interface seems like a more usable approach.
Cilium BGP is used to advertise PodCIDRs and Service CIDRs, enabling dynamic routing of pod and service networks across the data-center fabric.

You can find the implementation details and lab setup here: GitHub: cilium-containerlab-bgp-multihoming

The content of this post was created by the author; AI was used for editing and restructuring.