Cisco 3750 what does it mean to have ip route 10.0.0.0 255.255.255.0 0.0.0.0

[Fraydoon Razazi]

Could some one explain what the command

ip route 10.0.0.0 255.255.255.0 0.0.0.0

will result in?

Thanks,

[cadet alain]

Hi,

it's not a valid command  so it will be rejected because the only  value after the mask is the administrative distance which is an integer between 1 and 255.

Regards

Alain

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[Fraydoon Razazi]

Alain,

This is from a running configuration and I believe it is refrencing the null0 interface but haven't found any documentation to verify that.

So the command is a valid command but does it equal to:

ip route 10.0.0.0 255.255.255.0 null 0

Thanks,

Fraydoon

[johnnylingo]

It routes 10.0.0.0/24 via the default route. 

If there is no default route, then the route is ignored. 

[aLeffingwell]

Is it safe to assume in this situation that if the route to 10.0.0.0 is to go to the default gateway, that you could just simply remove this route and have the same net effect? (assuming a default route exists).

[johnnylingo]

If there's a shorter prefix (say 10.0.0.0/8) with a different next hop, the 10.0.0.0/24 may be an attempt to create an exception.  So removing it could actually have an ill effect.

[pille1234]

Assuming there is a valid default route set, would 10.0.0.0/24 be visible in the routing table?

[johnnylingo]

Yes, if there is a valid default route, 10.0.0.0/24 should show up in the routing table.  Assuming you have "ip classless" configured.

[pille1234]

Interesting. I get the message "%Invalid next hop, looping back to the network", but the route is still inserted into the routing table and obviously the recursive lookup works anyway.