From: Joe (joe.clyde@utah.edu)
Date: Fri Nov 14 2008 - 15:46:38 ARST
I have a question on recursive lookups, hopefully I can phrase it in a way
that makes sense. Thanks
If I have a static route like:
Ip route 11.11.11.0 255.255.255.0 10.10.10.1
And I have a route table that looks something like this:
C 10.10.10.0/24 via int X
O 10.10.0.0/16 via x.x.x.x
E 10.0.0.0/8 via x.x.x.x
B 0.0.0.0
Hopefully you get the idea of the route table...doesn't matter how the
routes are learned... just the idea of multiple routes (each less specific).
What happens when I lose my directly connected interface? How "un-specific"
of a route will the router use for a recursive lookup? *I know in this
example if I lost the /24 then the next most specific /16 in this case is
next in line but at what point will the router say it won't use a valid
route (as far as the route table) for a recursive lookup?
I don't believe it will ever use a default route but it seems like I've seen
it try to recurse off a /14 route. In my opinion that is an undesirable
behavior (let's say you have a summary address to null 0, you wouldn't want
you statics still showing up as accessible because the next hop is reachable
via a /16 net lets say). I know, I can avoid that issue by adding a specific
interface to the static route, but would still like to know at what point do
I not do a recursive lookup. Thanks for the help
Blogs and organic groups at http://www.ccie.net
This archive was generated by hypermail 2.1.4 : Mon Dec 01 2008 - 08:18:30 ARST