Wireshark · Ethereal-users: [Ethereal-users] looking to make passive tap

["Robert P. Britton" <rbritton@xxxxxxx>]

I was using ethereal to sniff a switch bank (cisco 2950/3548 switches…about 8 of them).

 

I was using port mirroring on one of the switches to try and sniff down some errors that were occurring on our LAN.

 

The results for runts, jabber, etc, were all coming up showing none.

 

I put an email into cisco, and they basically said that one of the jobs of a switch is to eliminate physical layer problems like that and that I needed to buy a tap.

 

I found a tap (it’s like $1000), but found a link where they were talking about how to make a full duplex 100mb passive tap using a patch cable. Unfortunately, they did not really explain HOW to make it…only that it was possible.

 

My boss wants me to make one because we don’t have the money to buy the $1000 passive tap.

 

Does anyone have any links or documents describing how to make one of these so that we can pick up on physical link errors?