Change EIGRP default route method - will it break routing?

[jkeeffe]

Right now we configure all our routers with a static default route like:

ip route 0.0.0.0 0.0.0.0 192.168.100.1

192.168.100.1 is the inside interface of the router right before our firewall to the Internet, I'll call it Router-1.

The outside interface of Router-1, that connects to our firewall, is 192.168.10.1 and the firewall is 192.168.10.2

I want to change how our routers know about the default route by adding a static default route and redistributing it into the routing table on Router-1 like:

router eigrp 1

redistribute static

ip route 0.0.0.0 0.0.0.0 192.168.100.1

1. When I enter that into Router-1, and the default route gets propagated throughout the network, how will that affect all the other routers that still have their own static defaul route of 'ip route 0.0.0.0 0.0.0.0 192.168.100.1' in them?

2. To clean things up should I then go to all the other routers and remove their individual defaul route statement, thus relying only on Router-1's redistribution of the static default route?

[mmorris11]

Jim,

Congrats on observing this opportunity. This is somthing that rarely gets cleaned up in a network. ANyway, Redistributing the static default route will propogate to the routers in eigrp 1 via the topology table, but the routers which have static routes configured will prefer those routes. Thus, redistributing this route as you have described is a low risk proposistion. WHat you will want to do next is go to a router in the eigrp 1 as and try removing the default route and see if the routing table then becomes populated with the one in the topology table. What you should see is that the next address corresponding to the default eigrp provided route is the next hop address of the upstream router. There are even fancier things you can do also.

http://www.cisco.com/en/US/customer/tech/tk365/technologies_white_paper09186a0080094cb7.shtml#defaultrouting

HTH pls rate!

[gpulos]

what this will do is keep both default routes.

the one that is static will be considered the best selection, as it is static versus a routing protocol learned route.

it is best to go to every router, after you redistribute the new default route, and delete the static default route.

NOTE: verify each routers routing table contains the new learned route properly before you delete the static default route.