Default Rout using: ip default-network

Unanswered Question
Jun 22nd, 2009


I am a little confused with how to use the ip default-network command to configure a default route. Can someone explain the difference using "ip default-network" and "ip route"?


I have this problem too.
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Jerry Ye Mon, 06/22/2009 - 19:21

Hi Francisco,

You would use ip default-network when your device is configured with no ip routing. It really means device doesn't need to perform any kind of routing (like a PC) and use the IP address as its default router/gateway.

When you are using ip route, ip routing must be configured. ip route means you want to set up a static route for certain destination.



Jerry Ye Tue, 06/23/2009 - 06:27

More correction,

ip default-network is used to select a network as a candidate route for

ip route is static route entry that will go into the routing table.

To explain this in an example:

ip route

ip default-network

when a packet destinated to network, router will route it to, at the same time, when a packet destinated to network has no specific match in the routing table (, router will use the and send it to network.



Giuseppe Larosa Tue, 06/23/2009 - 06:18

Hello Francisco,

some protocols support the ip default-network concept:

instead of simply specifying a default gateway or advertising a default route, the protocol can send out an advertisement for the IP subnet of the default network with a special flag that says that it can be used as exit point to outside world.

The protocols that support ip default-network are RIP, IGRP and EIGRP.

To be noted that the ip default-network have to reference a different major network (class A,B, C) then the one used internally.

Also EIGRP and IGRP require a network command for the ip subnet for being able to send the IP route with the external flag.

Hope to help



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