Hi, I just want to say thanks to all, especially Wybnormal for helping me resolve the configuration problem. Thank you for your patient. So my router is up and running now. I can ping any address both from my client and router 2514. There is one problem still remail though. I can't ping any address from my router 2501 which connect via serail port to Router 2514. Shall I enable the RIP on My 2514 or other routing protocol?