To access to your switch or router through a serial cable you can use tools like kermit or minicom.
To access with kermit in a debian machine you can simple install it with:
# apt-get install ckermit
To run kermit I use this config file in my home directory
$ cat .kermrc set carrier-watch off set handshake none set flow-control none set line /dev/ttyS0
Once you have connected the serial cable on ttyS0 you can run kermit command:
$ kermit C-Kermit 8.0.211, 10 Apr 2004, for Linux Copyright (C) 1985, 2004, Trustees of Columbia University in the City of New York. Type ? or HELP for help. (/user/) C-Kermit>
Now, simple type connect kermit command to access to your router:
(/user/) C-Kermit>connect Connecting to /dev/ttyS0, speed 9600 Escape character: Ctrl-\ (ASCII 28, FS): enabled Type the escape character followed by C to get back, or followed by ? to see other options. ---------------------------------------------------- Router>
This is simple way to access to your router or switch and configure it.