[TriLUG] Slightly OT: Connecting a Cisco router to a Linux box via serial connection?

[Chris Bullock]

Phillip Rhodes wrote:

> Hi guys, have a question for you router experts! I'm thinking about 
> going for my CCNA certification, and found today that we have a spare 
> (old) Cisco 1601-R laying around the office not being used.  I thought 
> I'd set it up in a spare cube and use it to play around with as I 
> learn Cisco router stuff.

When I took the CCNA, there wasn't any need to set up "external" 
interfaces, only know the protocols associated with it.

>
> The issue I have though, is that this Cisco box was designed strictly 
> for connecting WAN -> LAN. That is, it has one Ethernet interface, and 
> one serial interface only (plus a slot for an optional WAN interface 
> card).
>
> So, given that,  Could I possibly do a straight serial -> serial 
> connection to a Linux box setup to simulate the upstream router at an 
> ISP? If so, I'd appreciate any pointers on how to proceed...

I believe the term serial for the Cisco is a little different than a 
standard pc serial port but I am not sure.  Plus you would have to have 
a CSU/DSU card for 1 or both machines, which depending on you router it 
may be build in to the WAN card

>
> Oh, I should probably add that I'm willing to purchase either another 
> WAN interface for the Cisco, and/or additional interface boards for my 
> PC, if needed, assuming the price isn't outrageous.

Depends on what you consider outrageous, last time I checked the card 
was >$500 for the Cisco and ~$900 for the Linux card

>
> Some Google searching indicates that it's not easy (if possible) to 
> connect the Cisco serial port to a PC serial port, due to the Cisco 
> being synchronous only, and the PC asynchronous only. However, I 
> understand that you can buy a synchronous serial interface board for a 
> PC... so if something like this would be an option, I'd go that route 
> (no pun intended), as long as it's not too expensive.
>
> More info is still appreciated though.. for example, if what I'm 
> describing is even possible, I'd need to know what kind of board to 
> buy for the PC and maybe some pointers on how to configure this setup...
>
> Or if it's just plain not possible, somebody please tell me so I won't 
> waste time on this.

I would investigate to see if there is a product called freesco still 
floating around, which used to be a linux distro dedicated to Cisco 
routing, or try VMware.  Or go to your local bookstore and buy the 
ExamCram CCNA study guide.

>
>
> Thanks,
>
> Phillip R.
>