I’ve just realised I didn’t publish yesterday’s posting. I’m still getting used to this blogging lark, and I must have clicked “Save” instead of “Publish”. Anyways, it’s there now.
I’ve got a 3 a.m. bout of insomnia, so I’ve just done some experiments with the routing protocols and static neighbors. Each protocol behaves differently. I am too tired to write up the experiment fully, but here are the conclusions:
RIP: When you configure a static neighbor, RIP continues to multicast on the network as well as sending unicasts to the neighbor. If you configure passive-interface, the unicasts can penetrate the wall, but the multicasts are blocked.
EIGRP: When you configure a static neighbor, EIGRP stops sending multicasts on the network, replacing them with the unicast. If you configure passive-interface, it blocks the unicast as well. Moreover, you cannot mix static and multicast between two neighbors; that is, you cannot configure a static neighbor on one side and the neighbor still sending multicast. They just don’t form the adjacency.
OSPF does not allow static neighbors except in non-broadcast networks, i.e. NBMA or P2MP-NB. In that case, the multicasts are switched off anyway. passive-interface will block the unicasts as well. If you have a broadcast network, the only thing you can use the neighbor command for is to modify the cost for that neighbor.
Now I’m going back to bed.
