Linux-Hams archive - July 1997: confusion over routing with rspf

confusion over routing with rspf

Mike Bilow ()
Fri, 04 Jul 97 08:49:00 -0000


Terry Dawson wrote in a message to Mike Bilow:

TD> I use a manually defined default route as the catch all and
TD> let rspf handle the exception. This seems to work fairly
TD> well, though I can fairly easily imagine scenarios where
TD> this might not work. You always have the option of starting
TD> with no routes and just waiting for rspf to build them for
TD> you. Isn't it true that when I am first detected as a new
TD> adjacency my neighbours should perform a full routing
TD> broadcast for me ? If not, I wonder if it shouldn't be, or
TD> if some functional equivalent to an 'rspf query' could not
TD> be implemented so that when I start, and find an adjacency I
TD> can ask them to tell me what they know?

This was discussed at one point early in the development of RSPF, and it is a
tempting thing to try. However, a little thinking about it leads to the
realization that it would provide an opportunity for catastrophic failure where
routers forcibly update each other and prevent useful traffic from passing over
the channel hogged by routing updates. These sorts of things have actually
happened in real networks, and they have been studied extensively. There are
also security concerns, since a spoof could start a thrashing condition that
would quickly bring down the whole network.

-- Mike