North American Network Operators Group Date Prev | Date Next | Date Index | Thread Index | Author Index | Historical Re: Domain names for ISP infrastructure links
> > > I'm puzzled. Connections go from router to router. How does it help to say > > > routerb-x-y-z-routerc.blah.net when routerc will show up as the next hop in > > > the traceroute? > > > > I think it will help when routerc fails to show up as the next hop :) > > No. Actually yes. At first I had the same thought that you did, but knowing which router the packet was supposed to have come from makes it easy to tell from the output of a traceroute weather the routing changed in the middle. Having to use IP addresses to figure this out is much more work. On the other hand, I do question the idea of trying to cram all this info into the the interface names in the DNS. > > Traceroute gives you the incoming interface on a router. For a given > incoming interface on a router there are multiple next hop routers > (and multiple outgoing interfaces). > > Knowing that the outgoing interface that a packet came from on the > previous hop router is not worth adding to the DNS. > > If this is a point-to-point link, as you seem to be assuming, then it > should be subnetted as a /30 and you can thus subtract or add 1 to the > IP address as appropriate to find the previous hop's outgoing > interface, if that information is important to you. > > If it is a multiple-access link, then there is no chance of the > incoming interface being specific to a particular previous hop anyway, > so this scheme falls apart. > > --jhawk > - - - - - - - - - - - - - - - - - |