Linux-Hams archive - May 1997: Re: rspfd again

Re: rspfd again


Thu, 1 May 1997 20:35:38 +1000 (EST)

Mike Bilow typed:
>
>
> Simon J Mudd wrote in a message to Mike Bilow:
>
> SJM> understood. However it would be nice if (under an option)
> SJM> the rspfd could enable proxy arping on an interface it
> SJM> controls, IFF it knows it is the "right" gateway for the
> SJM> station doing an arp request. I guess the problem here is
> SJM> there is a potential conflict where more than one routing
> SJM> station thinks it has a route: ideally the one with the
> SJM> shortest path should answer, but I imagine the solution to
> SJM> this is not trivial.
>
> I cannot emphasize strongly enough that combining proxy ARP with RSPF is a
> really bad idea. I don't mean a slightly bad idea, but an extremely bad idea.
I would agree here with Mike and go on to say that static proxy ARPs are a
bad idea, but having RSPFd dynamically proxy ARP for links it can get to is
asking for trouble.

> RSPF is supposed to monitor the ARP table for prospective adjacencies. In
> theory, any change in the ARP table does represent at least a one-way
> adjacency, but proxy ARP messes this up completely. All of the RSPF routers
Which it does, RSPF needs proxies to be who they say they are to build a
better map of its surroundings.

> SJM> Otherwise "stale" dynamic routes won't be very dynamic :-)
> SJM> Dynamic routes don't have a TTL field in the kernel routing
> SJM> table do they? How do other routers solve this problem?
>
> RSPF defines the process by which routes should become suspect and, if tested
> and found bad, removed.
He's referring to routes that are added by RSPFd, then RSPFd crashes or is
restarted. The new process will ignore these routes placed into the routing
table.

- Craig

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