Q I'm thinking about upgrading my home network to Gigabit Ethernet. All my computers have gigabit network cards, but my router has a four-port 10/100 Ethernet switch built in. If I connect my router to a Gigabit switch, and connect all my computers to the Gigabit switch will I achieve Gigabit speeds, or do I need a Gigabit router?
A The only traffic that would need to go through your router if you did this would be the traffic that goes to or from the internet. The only reason all traffic goes though your router device now is that it also contains the network switch, but the data doesn't actually go through the router part of the device unless it needs to reach the Big Bad Web. Any traffic between two computers directly connected to the switch would communicate at the maximum possible speed, which would be Gigabit if both had Gigabit network cards. Your router is a 100Mbit device and would be connected to the Gigabit switch, but this would not affect the speeds between other devices.
Unlike a hub, which operates at the speed of the slowest device connected to it, data flowing through a switch only goes between the two devices involved in the transfer and is unaffected by anything else on the switch. The same goes if you had a computer with a 10/100 network card connected to the switch, only transfers involving this device would drop to 100Mbit speeds. You can find Gigabit broadband routers, but they're more expensive and the only difference is that the built-in switch is Gigabit. If your router needs to be replaced, one of these might be worthwhile, but otherwise add a Gigabit switch and you'll get the same performance and more network ports.