Static Route Question

[krausjw]

What's going on?

I have a question for the group on IP static routes.

I'm studying a book that lists, in several

different places, the static route statement:

ip route 172.16.2.1 255.255.255.255 Dialer2

Is the subnet mask of 255.255.255.255 a typo, or is it the proper syntax for a point-to-point route

out of the Dialer2 interface? I haven't found

any similar examples in the Cisco documentation.

Thx, JWK

[micah]

The subnet mask of 255.255.255.255 indicates a single ip address. This will route only 172.16.2.1 to the dialer2 interface.

[eapenten]

I think the routing statement is there to allow broadcast traffic and this is rightly so with dial-on-demand routing (DDR) for ISDN networks.

Ex.

ip route 0.0.0.0 0.0.0.0 10.1.1.1 ip route 10.1.1.1 255.255.255.255 BRI0

would inform the router that in order to reach any ip network not defined in its routing table (all zeros network), it will go to the ip address 10.1.1.1, and in order to get to the host ip number 10.1.1.1, it will go through interface BRI0.

It is not good to use 255.255.255.255 for an interface connected to the network because this will stop traffic on that interface.

I am aware that 255.255.255.255 may be used to configure GRE over IPSec where the GRE/IPSec tunnel is going through a firewall doing Network Address Translation (NAT).

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255.0.0.0 for a Class A address (those that begin with 1 to 127),

255.255.0.0 for Class B addresses (those that begin with 128 to 191),

255.255.255.0 for Class C addresses (those that begin with 192

and higher).

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I hope this helps in a way.

Emil............