quick network engineering review question

[Jonathan Hutchins]

On Wednesday 01 June 2005 03:51 pm, David Nicol wrote:

> I want to sniff all traffic on the upstream link at my installation.  I
> have a wire that comes into my cisco router from the CSU/DSU.  The question
> is, is this wire a normal ethernet wire, so that I could plug it into a hub
> and plug the hub into the Cisco, that is, put a hub in line with it, or is
> it something else?

Not a guaranteed answer, but I would say "no".  The wire from the telecom does 
not carry straight ethernet traffic, it's frame relay or dsl or something.  
you need some sort of modem device to translate to ethernet.

Depending on the Cisco unit you have, either the unit itself can output raw 
packet info for logging/analysis, or you can connect a computer to it to do 
the sniffing.

I recently ran "iptraf" on my firewall and determined that all that flickering 
on the RoadRunner modem was ARP packets.