> Russ> You need a unique identifier at the equipment level for > Russ> anything you intend to auto-configure --autoconfiguring > Russ> uniqueness is a very hard, probably impossible, problem on a > Russ> global scale. So we need to count on this one thing, no matter > Russ> what else we might need to back in to. > > Russ> Now, it might be possible to some hash over a GPS location for > Russ> a "base," and then add on MAC addresses, or some such, but > > We've assumed a unique MAC, which is 48 bits long. > But OSPF router-id is 32 bits. What is the likelyhood of a collision > in the bottom 32-bits of the MAC?
Ah, I see the problem... There is a pretty high likelihood of a collision, actually, at least as long as you use multiple vendors in your home network. It's bound to happen to someone, someplace. So, a suggestion to resolve this: 1. Use the lower 32 bits of one of the mac addresses on the box as the initial id. 2. Add a new field to the router capabilities that carries the full 48 bit mac address, or even some munged together "longer id," based on multiple mac addresses on the device, or some such. 3. During initial setup, if you receive a capability that appears to be from yourself, you open this secondary id section to find out if it's really you, or someone else who happens to have the same 32 bit id. 4. If it's really you, discard the packet. 5. If it's not really you, and if the other router's "large id" is lower than yours, choose another mac address from which to take your local id, and restart your ospf process. 6. If it's not really you, and the other router's "large id" is higher than yours, then send a router capabilities LSA unicast to this "other router," so the "other router" knows to change its id. I don't think IS-IS would have this problem. :-) Russ _______________________________________________ homenet mailing list [email protected] https://www.ietf.org/mailman/listinfo/homenet
