ISDN with multiple connection to HSRP routers

fvalpondi · ‎10-21-2009

Hi,

I got a question related to ISDN connecting three routers.

My topology is the following:

Net1----|

Net2---R1-|

.................|--------------------R3---Net3

Net2---R2-|

Net1----|

R1 and R2 are on HSRP (R1 is master) so that the Ethernet work as only one. Since ISDN interface cannot be used for HSRP I will have the ISDN interfaces as "independent" interfaces where the information will be routed according to the routing table.

When there is traffic from R1 or R2 to R3 should not be a problem to bring up the line. The problem is that in most of the cases it will be R3 who is dialling.

So, my question is, how can I configure R3 to decide where to dial depending on the HSRP active router? Is it possible?

If not, my idea was to call (via dialer map) R1, and if it does not answer, call R2. How can I do that? I've looked in the documentation available but I have not been able to find any helpful informationâ€¦

Thank you!

Regards,

Fabio

paolo bevilacqua · ‎10-21-2009

You cannot decide where to dial based on HSRP.

Seems to me you should use a different design based on routing, not HSRP.

fvalpondi · ‎10-21-2009

Thanks for your answer.

You have confirmed what I had thought. Now my other question.

Just discard now HSRP and suppose only R1,R2 and R3.

If R3 tries to dial to R1, and R1 does not answer because it's down, how can I make R3 to dial to R2?

If had thought two different dialer maps with two different numbers (one for each router). But it does not work for different IP addresses....or that is what I understood...

thanks again!

paolo bevilacqua · ‎10-21-2009

Just use multiple dialer strings in dialer interface.

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fvalpondi · ‎10-21-2009

Hi,

thanks for the info.

I've looked for information, but I did not find how I have to configure a dialer interface to dial to a second number if the first number does not answer.... :-(

Is there any special command?

regards,

Fabio

paolo bevilacqua · ‎10-22-2009

It's called dialer profile with dialer pool, it's the standard configuration.

slmansfield · ‎10-22-2009

Here is a URL that describes how to get a dialer interface to call alternate numbers using legacy or dialer profiles. HTH

http://www.cisco.com/en/US/docs/ios/dial/configuration/guide/dia_rotate_dial_strgs.pdf

fvalpondi · ‎10-22-2009

Thank you all! I will try it today and I'll inform you about the results :-)