We have two sites, A (central office) and B (remote), connected via a transparent LAN connection with ethernet handoff to our 2800 routers. They are EIGRP neighbors. I upgraded the IOS for site A to a newer T release and reloaded, but an adjacency never formed between the two sites.
Upon further investigation, it appears that the line protocol for site B on that interface actually went down. In the sh log for site B, I see the following at the time I reloaded site A:
Sep 17 07:20:15: %LINEPROTO-5-UPDOWN: Line protocol on Interface GigabitEthernet0/1, changed state to down
Sep 17 07:20:15: %DUAL-5-NBRCHANGE: IP-EIGRP(0) 1: Neighbor 192.168.X.X (GigabitEthernet0/1) is down: interface down
This seems strange to me, as I would only expect the %DUAL-5-NBRCHANGE and not the %LINEPROTO-5-UPDOWN at site B. What could have caused this to happen?
A sh int g0/1 on site B gives "GigabitEthernet0/1 is up, line protocol is down." Site A's int is up/up.