[6828] in North American Network Operators' Group
Re: Domain names for ISP infrastructure links
daemon@ATHENA.MIT.EDU (Rob Liebschutz)
Tue Jan 7 19:13:11 1997
Date: Tue, 7 Jan 97 16:10:32 PST
From: Rob Liebschutz <rob@rjl.com>
To: John Hawkinson <jhawk@bbnplanet.com>
Cc: perry@piermont.com, nanog@merit.edu
In-Reply-To: Your message of Tue, 7 Jan 1997 17:26:27 -0500 (EST)
> > > 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
>
