Full duplex standard Ethernet is capable of transmitting 20 mega bits per second while 100bast-tx full duplex operation allows 200 mega bits per second to be transferred. At the center of each star is a hub or a switch . The differences between hubs and switches are the amount of intelligence in each. Both hubs and switches use a store and forward architecture so collisions are avoided most of the time. The difference between a hub and a switch is that hubs retransmit everything they receive to every node on the network while switches examine each packet and route the packet to the right destination.
Switches are more expensive than hubs but they allow full duplex operation.
We will be using a mixture of both. In estimating the cost of this project I have deliberately used prices from the highest price vendors, those who maintain full stocks, supply unlimited technical support and 24 hour parts replacement. I have mixed products from Cisco, Bay Networks and 3Com as well as some others. Since this project will eventually be placed by open bidding I have not mentioned vendors in the list below. While I could have optimized this parts list for either network efficiency or minimal cost I chose to use a minimum number of discrete parts as my criteria.