IP default-network command help

MrXpert

Can anyone tell me what the point is of this "ip default network" command?
I issued it in global config mode, typed "ip default-network 200.0.0.0" and realised that I also had to run the "network 200.0.0.0" cmd on the same router.

I did a "show ip route" on the remote router and it gave me this

Gateway of last resort is 172.16.2.1 to network 200.0.0.0

200.0.0.0/30 is subnetted, 1 subnets
D* 200.0.0.0 [90/2681856] via 172.16.2.1, 00:00:10, Serial0/0
20.0.0.0/16 is subnetted, 4 subnets
C 20.4.0.0 is directly connected, Loopback2
D 20.1.0.0 [90/2809856] via 172.16.2.1, 00:01:26, Serial0/0
D 20.2.0.0 [90/2809856] via 172.16.2.1, 00:01:26, Serial0/0
C 20.3.0.0 is directly connected, Loopback1
172.16.0.0/24 is subnetted, 2 subnets
D 172.16.1.0 [90/2681856] via 172.16.2.1, 00:01:26, Serial0/0
C 172.16.2.0 is directly connected, Serial0/0

But whats the point of this command? i mean could i not achieve the same thing with a static route which is redistributed using "redistribute eigrp connected"? or even create a static route and then use "redistribute eigrp static"? this would make it a default candidate D EX route when you look at it at the remote end ? but AD would be 170? isn't this really the same thing as the ip default-network command?

NetworkVeteran

MrXpert wrote: »

Can anyone tell me what the point is of this "ip default network" command?

Gateway of last resort is 172.16.2.1 to network 200.0.0.0

200.0.0.0/30 is subnetted, 1 subnets
D* 200.0.0.0 [90/2681856] via 172.16.2.1, 00:00:10, Serial0/0

i mean could i not achieve the same thing with a static route which is redistributed using "redistribute eigrp connected"?

Nope. If you created a static 0.0.0.0/0.0.0.0 route and then redistributed static.. the routing table would contain less information (despite having to send more updates!). Specifically, it would need to send an extra external route in its updates, and the routing table would not reveal which network(s) were the exit point(s) of your autonomous system. Of course, this only applies to routing protocols that can take advantage of this extra information, but the EIGRP which you are running happens to be one of them.

NetworkVeteran

PS - You've left out a couple more options for specifying the default route in EIGRP--
1. You can use, "network 0.0.0.0".
2. You can use, "ip summary-address eigrp".