[6825] in North American Network Operators' Group
Re: Domain names for ISP infrastructure links
daemon@ATHENA.MIT.EDU (John Hawkinson)
Tue Jan 7 17:30:59 1997
From: John Hawkinson <jhawk@bbnplanet.com>
To: perry@piermont.com
Date: Tue, 7 Jan 1997 17:26:27 -0500 (EST)
Cc: nanog@merit.edu
In-Reply-To: <199701072212.RAA23400@jekyll.piermont.com> from "Perry E. Metzger" at Jan 7, 97 05:12:47 pm
> > 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.
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
