Ip-address ISDN/Router to Router (next-hop-address'')

[gjrono]

Hello!

Anyone who know if "next-hop-address" in dialer string on a cisco router has to bee the same as the ip-address on the dialer interface on the opposite router.

Example:
Router 1
Dialer map ip 10.1.1.1 name Router2 66554433

Does the Router2 ned ip-address 10.1.1.1 on the dialer interface.

I have tried with different addresses, event different subnets and it looks like working fine. Would this cause any problem?

Regards
Gjermund

 

[ccie9545]

yes, it could potentially cause some problems....there are problems with routing that may pop up...espcially if you are running a routing protocol over the link and the two ends are on different subnets.

if you have routes that point to the incorrect IP address the routing will fail.

The dialer map is a method of mapping the layer 2 ISND number to the layer 3 IP address. If you have a route that points to something other than the IP address in the dialer map, the call may not be made. Further, if you are sending packets to an IP address that does not exist you experience some problems as well.

Was there a reason that you wanted to use a different IP address on the remote router than you have confiugred in the dialer map? Erik Rudnick, CCIE No. 9545
mailto:erik@kuriosity.com

 

[gjrono]

Hello!

Thanks for the answer. Sorry i am late to give you an answer.

My reason for wanting to have different ip-addresses is that internaly we use ips in rang 10.12.0.0 and to save official addresse on the dialer interface i wanted to reserve a number of internal ip-addressen in the 10.12 network, to use as next-hoop address. We have about 50 customers on the customers router, and sometimes it is hard to get official ip-adsresses for the "dialer communication" from the customers.

What do you mean "espcially if you are running a routing protocol over the link and the two ends are on different subnets"

In my cases where i have used different ip-adresses it has seemed to work fine. I route an official ip to a next hoop address in 10.12 network. route then the 10.12 to the dialer interface where i have the dialer string with that 10.12 address. The custommer has to route the trafic back to the same dialer interface on his side?

I dont know if this lousy explained?

Regards
Gjermund