RIP Metric export to kernel table ?

[Mario Lorenz]

Am 20. Jun 2000, um 01:32:02 schrieb Martin Mares:
> Hello!


> 	protocol static {
> 		preference 201;
> 		route 10.0.0.0/8 via 192.168.0.1;
> 	}
> 
> 	# I definitely should teach BIRD to recognize preferences in static
> 	# route definitions to avoid needing to configure two static protocols
> 	# or a filter in order to have static routes with different preferences. --mj
> 	protocol static {
> 		preference 200;
> 		route 10.0.0.0/8 via 192.168.0.2;
> 	}


For two static routes, I wouldnt need bird at all :)
The problem I have is that the VPN, since it runs over ethernet and then
some, the link state gets not changed.

Even on the ppp interface, as I see it, the interface is always UP, regardless
on wheter the line is or not.

The Idea I had was to set up a route with metric 8 to the PPP link, and have
RIP run via the VPN with a metric of 4. If the rip times out, ie the route
vanishes at one end, the metric 8 route kicks in  autodials the modem.

Then on the other end, the modem would by ip-up-script set a route metric 0
back so that the ppp link is used immediately. Thats why I needed bird to give
the higher metric to the kernel table.

After I hacked bird to put the metric into kernel space I got it working
that way.

However I found out that this was not so good an idea after all, because
now, if
the VPN becomes available again, only the first end switches back to the vpn
while the second end (due to the metric 0 route) still uses the PPP link.
And that means the ppp link doesnt idle out. 

So I scratched that higher priority stuff. I have now in general a metric of
8 via the ppp link, and a metric of 0 via the VPN. I now have to wait a
little longer until both ends time out on the rip, but well..

Now whats the "proper" way to do this ? Besides adding a cisco where one has
reliable link state indication (as ANK wrote somewhere in his docs, Linux is
not a real router ...)


Mario

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Mario Lorenz                            Internet:    <ml at vdazone.org>
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