ISDN Multiple Dialer sequential dialing

Unanswered Question
Mar 3rd, 2007


I need to implement ISDN redundancy in the following scenario.

I have a Edge Router which has a BRI interface. The router gets Routes from the Core Router where the Servers are kept which would be accessed from the people located behind the Edge Router. The Edge Router connects to the Distribution Router which inturn connects to the Core Router. The network is running OSPF. The Distribution Router has a PRI interface. Similarly, I have more Distribution Routers located at other locations and Edge Routers connected to the Local Distribution Routers.

The Edge Router connects to the Distribution Router using a Leased Line. I require the Edge Router to watch a route from its routing table and when this route disappears, ISDN should first dial to the Local Distribution Router. If it doesn't receive the expected route after ISDN connection to Local Distribution Router, it should either disconnect/time-out and should dial an ISDN connection to the Nearest located Distribution Router. Incase, it doesn't receive the expected route from here too, then it should disconnect/time-out and then dial to the Core Router itself.

Presently, I have configured 3 dialer interfaces and 3 dialer watch-list. Please see the attached configuration template.

Whether the configuration in the template work? Also I do not want the ISDN to dial during non-business hours even if it doesn't receive the expected route. But since dialer watch-list is a way of triggering an ISDN connection, is it possible for dialer to realize the avaliability of interesting traffic first and then check for the expected route before dialing an ISDN connection?

Thanks in advance.



I have this problem too.
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hadbou Thu, 03/08/2007 - 11:53

The Rotating Through Dial Strings feature allows you to specify the dialing order when multiple dial strings are configured. Options for dialing order are as follows:

Sequential?Dial using the first dial string configured in a list of multiple strings.

Round-robin?Dial using the dial string following the most recently successful dial string.

Last successful call?Dial using the most recently successful dial string.

Try this link:

sridharvaidyanathan Thu, 03/08/2007 - 23:15


But incase of multiple dialer string, the Edge Router would dial to the Nearby Distribution Router only incase the PRI interface in the Local Distribution Router is down. What if, the PRI interface is UP and its able to connect to the Local Distribution Router but its not getting the Server Subnet routes from it since the Link between the Distribution Router and Core Router is down.




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