/ networking

Redundant GRE on linux with keepalived and multicast routing

Generic Routing Encapsulation is nice and old tunneling protocol that is very helpful with use cases where you have to encapsulate some network layer protocol over IP network.

Following diagram presents the architecture solving one of the problem I've struggled recently. It's showing how to implement HA on top of two GRE endpoints so in case of a failure packets are send to the backup gateway.
One of the requirements is to have multicast routing enabled and for that reason smcrouted has been used