On Mon, 2006-01-30 at 08:21 -0600, Les Mikesell wrote: > The distinction is fuzzy because there are some expensive devices > called 'layer 3 switches' that understand IP addresses and can > do some routing and filtering based on them. However what is > normally called a switch works at the network layer 2, using > only ethernet MAC addresses. They learn the hardware addresses > of the connected devices as packets are sent from them and once > a destination is known they will only forward packets to that > destination out the correct port. Wouldn't they also have to be co-relating IPs to MAC addresses? Surely they couldn't just work by the MAC, alone? For instance if my PC at 192.168.1.1 wants to do something with 192.168.1.2, all that goes out on the wire is the IP addresses, hoping that something else figures out how to connect the two together, or hoping that they're already directly connected together. >From the manual (tiny bit of paper) that came with my simple switch, I understood that it listened in on the traffic, worked out what IPs belong to what MACs, and switched accordingly after a few initial moments of discovering how the network was set up. If an IP or a MAC changed for a device (just one, and not necessarily both), it'd need to rethink things before it worked again. I can't say what switch I have, it's a black box, in a dark spot in the shelf. I can't see anything to identify it, just the blinking LEDs on the front. -- Don't send private replies to my address, the mailbox is ignored. I read messages from the public lists.
