Serial port with identity crisis

[Tim Ross]

I have been upgrading a couple 3104 routers (2 serial port, 1 ether, 1 BRI) and got them up and running on 11.1 IOS as DTE devices into an AGS+ operating as a frame-switch. The two 3104's can ping each other, but can't ping its own serial port. This is the first time that I have had this happen. I can ping a remote serial port, but not the local serial port. Can someone explain why this happens? Since this, I have upgraded the (2) 3104's to IOS ver 12.0.9 and am having worse problems, but am still curious about the local router unable to ping its own ser0 port.   Thanks, Tim