Since the administrator wants to upgrade his company’s network from a ring topology to a star topology he is wise in using a fiber optic cable. Since the network will be using Ethernet architecture with the CMSA/CD access method, I recommend he go with the 1000Base-SX standard for this. The 1000Base- SX will allow for a faster rate of travel for his data. Since this is a mid-size company, I am thinking the building size is probably no more than 5 stories high.
Depending on the number of microns his cabling will have he can get anywhere between 275-550 meters from this method. The 1000Base-SX gives him the range span of running the new wiring through the ceilings which may be obstructed by a few obstacles. He has probably already figured having multiple routers on each floor, which will cut his distance down between runs, as well increasing his networking speed through-out the building.
Without seeing the structure of the building in which he plans to upgrade it is hard to tell whether he will need to leave any part of the network completely a token ring. Considering a few factors though as far as security or vaults then I would consider using Message switching to connect to another device. Based solely on security once the message has been delivered the two devices will break connection therefore leaving no chance for data corruptions or hackers to get in your network.
Another good point to make will be that this since this works under the network layer of…