On Fri, Mar 21, 2003 at 04:33:51PM +1200, Gareth Williams wrote: > One more question, if I may - I thought bridges were switched (at the ethernet > layer). You imply that a bridge is simply a 2 port hub (and can be switched > or unswitched/broadcast, depending on complexity). I got the idea somewhere > that a bridge's intended function was different from a hub... > ie. hub -> join end terminals together > bridge -> join networks together > Now I think about it for a couple of seconds, the actual functionality is > pretty much identical, no? So... is then "hub" just another word for "bridge" > (ie. they are essentially the same device) ?
Yes, they are the same ... a bridge was originally conceived as a two-port device, but when manufacturers figured out to put multiple ports on the devide, they started to look for new names. And as they had effectively created a star-topology network from Ethernet, the name 'hub' worked for them :-) > ps. still not sure I "get" NAT (isn't it supposed to save address space? how's > that, if it's 1-to-1 direct mapped..?) ... but I'll google for that one :-) Network Address Translation does just what it says on the box - translates network addresses :-) That's defined as a 1-to-1 exchange. Useful in places like firewalled environemnts, where you need to ensure that hosts can only talk to each other via the mediation of the firewall. It's also useful whjere you are joining two previously unrelated networks, that have both been configured to use the same ranges (i.e. all my private networks are 10.n.n.n) - you can put one NAT box between them, instead of renumbering the whole of one of your networks. IP Masquerade (source address NAT) is the space-saving mechanism you're thinking of ... -jim
