Re: Double router in a network and cached routes

[Tomas Beinaravicius <tobe@nomagic.com>]

On Wed, 29 Aug 2001, Andres Seco Hernandez wrote:

> Hi all
> 
> I have a problem with the cache of routing in a single interface machine
> in a network with tho routers (one is only a router and the other is a
> firewall).
> 
> Routing in all computers is set to the router A, who has manual entries to
> a lot of internal networks. This router A has a default gateway for
> router B (the firewall) to reach the internet.
> 
> All is good except when a machine (client machine) in a network reached
> using router A is down (failed machine). router A then tells "client
> computer" who wants to send packages to the "failed machine" to route
> then using router B (the firewall). So, the "client machine" adds a
> routing entry in its table visible only with "route -C", but i can not
> delete that entry. I use "mon" to check that computer a lot of times, so
> the routing cache about the failed machine is cleaned never. If i stops
> the mon daemon, the routing cache cleans automatically some time after,
> and i can re-start mon again without problems.
> 
> How can i clean the routing cache manually? Or, can i force shortest time
> for the cache to be cleaned?

Andrez,

First of all, you may disable ICMP redirects on A, then route to B will
never appear on client machines.

Second, you may put B on a different subnet than client machines, the
routing entry will not appear either.

--
Tomas Beinaravicius
System Administrator
No Magic
P.O.Box 2166, LT-3000, Kaunas