Subject: Re: kern/3508 bug: cached ip route and interface up/down.
To: Nick Amato <>
From: Tad Hunt <>
List: tech-net
Date: 11/12/2002 16:37:12
In message <>, you said:
;Yes, it is true.  A routing daemon cannot fix the problems in PR 3508.
;However, as long as there is an absence of an alternate route (i.e. default)
;while a destination is unreachable, it still works. 

Right, which is why hardly anybody is going to notice this problem,
unless they're using NetBSD as a router with very little traffic.

;When a route is deleted and added the old route has RTF_UP reset and the
;new route will be rtalloc'd in ip_output().
;Not very useful.  It seems to me that what needs to happen is to clear the
;cache whenever a more specific route than the cached route is added to
;the table.  I don't know how practical this is.

Not quite.  Because when there are alternate routes, and the more
specific route was deleted, it needs to fall back to the less-specific

I agree with Dennis Ferguson's point, that the routing table lookup
should be made cheap enough that caching is not required.