Each switch unit in a networking system shares its local state information among other switch units in the networking system, collectively referred to as the shared forwarding state. Each switch unit creates a respective set of output queues that correspond to ports on other switch unites based on the shared forwarding state. A received packet on an ingress switch unit operating in accordance with a first routing protocol instance can be enqueued on an output queue in the ingress switch; the packet is subsequently processed by the egress switch unit, operating in accordance with a second routing protocol instance that corresponds to the output queue.