i am using 1 , 16port hub and 11 mini hubs to distribute internet through cat5 cable, a total of 30 PCs are attached to my server through these hubs which is a windows NT 4 server, one main hub 16port is installed at my officeand the rest mini hubs are with the consumers. the problem is on my main hub sometimes the orange light of collision keeps on flashing continuously due to which all the PCs get disconnected with the server and internet stops working on them. by removing a PARTICULAR mini hub wire from the main hub all becomes normal. i have changed that mini hub with other one and the cat5 cable too but the problem with the same line continues. is this due to operating system on the PCs. i have got 1 windows NT4 server, 3 PCs of windows NT workstation , 20 of windows 98, and the rest are windows xp. can anyone help me to solve this problem . pls help its urgent. comebody suggested me for a switch instead of hub but i dont know anything bout a switch wat is it and can replacing the main 16 port hub with a switch can solve the problem? pls help

It sure sounds like you'd be much better served with a switch and only a few hubs rather than a single hub with sub-hubs strung on it. The problem with this lashup is that all the traffic on the entire network goes everywhere. A switch distrubutes the load to various "legs" based on traffic. In fact, I often install multiple NIC's in a server to separate the load even further. Each NIC goes to a switch which goes out from there. Also, remember that if you're mixing 10 and 100 mb cards on a hub, the whole thing will slow down to the speed of the slowest active computer .. so a 100 mb connection will often slow to 10mb .. and you'll see a lot of collisions while people are waiting. This is most common when the server is at 100mb and you have cascaded slow machines off a single "dumb" hub.