Catalyst 2950 Trunk links

well I have access to everything except the router since its managed by our voice/data company. I've spanned the port going from the switch to the firewall to another port and ran ethereal for a day but I didn't find anything.

is there a tool that can show me at the exact point its spiking what the source ip or mac is that is using up the bandwidth?

If you have a managed service you should be able to ask them if the T1 is truely maxing out. If it is then i would suggest getting something like Packeteer's Packet Shaper. You can get this on a week or two trial and install it on your link (it can be installed in-line as a pass-through so no ip's need changing). If this then shows that the traffic is rubbish (like Peer-to-Peer tunnelling through port 80 or spyware or something) then look at purchasing something to manage the bandwidth.

You could also look at what machine is utilising the traffic through the SPAN'd port and then investigate the machines to see what could be going on.

The issues sound like the bottle neck isn't in the LAN so investigate the T1 line.

Funny, I just stumbled on something. I had my firewalls bandwidth graphs opened as I was downloading an updated version of ethereal which is 18 megs. As I was downloading it, everything else started crawling. I looked back at my bandwidth graphs and the T1 was maxed out. I looked at my download window and it is downloading at 149KB/sec. My single download on my one machine was maxing it out.

It appears that any machine in my network can max the bandwidth downloading anything.

I did another test. I had a user in another office download a 100 meg file from microsoft. During the duration of the download every user in my office could barely browse.

Any suggestions?

I would talk to your internet provider about the T1 line. The problem doesn't seem to be in your local LAN.

is it normal though for any machine in the office to be able to max out the bandwidth though? Is that why you think theres something wrong with the T1?

Forgive as I am trying to fully understand so I can present it to them properly.

thanks for your help!