Does anyone know why spanning-tree would place the Fa0 interface on a c871 in to a self-looped state?
When we connect a PC to the interface everything works fine and the PC can ping the vlan1 interface on the router. As soon as we place a switch on the same port 'sh spanning-tree' shows:
Port 1 (FastEthernet0) of VLAN1 is self-looped
The router is on a customers site and they are connecting a Linksys SRW248G4, it is only connecting to the one port on the 871 router and the switch connects to nothing else.
Spanning-tree indicates that the router is root for vlan1.
Any ideas? The router is running c870-advipservicesk9-mz.124-4.T1