The Candidate Default Route (*) - Resources

Here's some resources on the use of the default candidate route aka ip
default-network.

All additions are welcome as always.

http://www.cisco.com/en/US/tech/tk365/technologies_tech_note09186a0080094374.shtml

It can be used to place a "candidate" default route (not necessarily a
0.0.0.0) route that is reachable in an upstream router to a router that
otherwise would not have reachability to that route.

It's not used as often but is great in a pinch and does not break the
"static default rule" in the lab.

Narbik gave us a lot of skillful uses for it in a variety of scenarios and
even how to filter the "*" itself. Nice.

1. You apply the command once and then go visit all of your routers and see
the magic.

2. The classful route (major network) must already be in the router's
routing table to be propagated.

3. The router that needs the route does not need to have the route in its
table of course.

4. I'd have to work out some scenarios but let me see if I can find one for
you... see attached. It should be there.

Here's a good summary but only for EIGRP:

There are 4 methods of creating a default candidate route in EIGRP:

- 'ip route 0.0.0.0 0.0.0.0' + 'network 0.0.0.0'

- 'ip summary-address eigrp X 0.0.0.0 0.0.0.0' + 'network 0.0.0.0'

- 'ip route 0.0.0.0 0.0.0.0' + 'network x.x.x.x' + 'redistribute static' <-
creates an external route
- 'ip address n.n.n.n' + 'ip default-gateway n.n.n.n' <- additional routes
may needed to indicate further subnets
   Every single method create a default candidate route.

-- 
Darby Weaver
Network Engineer
http://www.darbyslogs.blogspot.com
darbyweaver_at_yahoo.com
Blogs and organic groups at http://www.ccie.net