On Thu, 20 Mar 2003, Gareth Williams wrote: > On Thursday 20 March 2003 21:57, Mike Beattie wrote: > > What do you class as a router? A router is in charge of routing packets > > from one network onto another, and vice versa. Therefore, having only 2 > > sockets is quite acceptable. > > I thought the idea of a router was that it had to chose one particular route > (ie. interface?) from a selection, based on rules (routing tables etc)... If
Yes. > there is only one in, and out, then... where does a routing decision need to > be made? You're just linking 2 networks together.. if a packet hits one > interface that's destined for the other network, you retransmit it on the > other interface, otherwise you don't... Exactly, and this is a routing decision. Let's extend this a bit and attach a hub (a multi-port repeater) to the "home" side of the DSL router. Then the hub will just copy all of its input traffic to all of its output ports. So you could have a really cheap LAN. If you were connecting one port of the hub to the Internet via a DSL router, the router would take care of keeping the local traffic off the phone line, and only routing real outgoing traffic onto the Internet. Furthermore, an optional feature of routers can be IP masquerading, which basically consists of faking IP headers, but in this case allows you to connect multiple local clients to an Internet account with only one temporary IP address (as seen from the provider's side). If your router does not have this feature, and you can only get one IP address at a time from your ISP (as is usually the case on dial-up modem or ISDN connections) you could connect only one client at a time. I do not know how many simultaneous IP addresses you can get with DSL currently. Enough lecturing... > it shouldn't even need to 'speak' IP (unlike a router?) .... sounds > like an ethernet bridge to me, no? Yes, it does have to speak IP, because the routing decisions are made on the network layer, which is IP. Hopefully this will not start another debate about layer 2, 3, 4 whatever switching... Cheers, Helmut. +----------------+ | Helmut Walle | | [EMAIL PROTECTED] | | 03 - 388 39 54 | +----------------+
