hi frens, i got a 2500 and i wanted to upgrade my IOS throught TFTP or FTP , but i don have the AUI tranceiver. Can i back2back connect my router with my 2621 and upgrade via TFTP throught back2back 2 router. ?
I think you can do so if after connecting back to back and assigning ip on serial interface if you are able to ping your tftp server.
I think you will be connecting your tftp server on 2621 router ethernet interface? If yes just assign a static route on your 2500 to point to the ethernet of the 2621 router exiting via serial interface of 2500.
Try that and update if it works.