Catalyst 2950 Trunk links

Smurf is probably your best bet for an explanation, but I would assume that any one PC could suck up all your bandwidth unless you have a device in place that would throttle it.

if they didn't configure you're network to run with the gigbait ports I wouldn't change them. There maybe be a distinct reason for that.

It really depends on your budget. If you've got some money, look into some packet shaping/optimization appliances, or even ask your ISP about QoS/CoS. You could do some rate limiting at your firewall so that Internet downloads (http/ftp) aren't using up all of your bandwidth. Cacheing proxies are another good way of saving bandwidth, and are virtually free (assuming you have some spare time, knowledge of linux and some spare hardware lying around).

As for the 2950 gig ports, I would reconfigure the trunks to use them if you have no other uses for them.

If your maxing out the T and there is no plan on adding more bandwidth. I would try to use the srr-queue bandwidth limit command on the switchports of the devices that shouldn't need the speed the servers do. Also you said something about voice are you running VOIP on your network?




As I was typing this I just noticed this post was just brought back to life

I've noticed a similar issue at my office. One machine on the network can pretty much drink up all the bandwidth. The rest of the users will be accessing the LAN at crawling speeds. What I find odd about this scenario is that it's sporadic. It seems that some form of throttling must be put into place when implementing a T1 line. But why would this be? Could this be because it is indeed a dedicated line that the ISP feeds you and what is done with that dedicated line inside the LAN, is up to the network engineers.

ZiPPy

Since it's managed I suggest you check that all 24 individual channels are functional.