How to trigger ISDN even with no traffic

[bapatsubodh]

Hi,

We have configured ISDN as a back up to serial link from one location to other location. So whenever there is no traffic ISDN do not trigger ( as due to applied access-list and no interesting traffic ). we have permitted all traffic in access-list. But how can we configure ISDN/ Dialer to trigger as a backup to serial line even if there is no traffic interested traffic to other location. ( Other locations can not call to this location due to some admin problem ). So call must initiaye from this location only.

Thanks in advnace

Subodh

[sundar.palaniappan]

Hi,

I assume you are using the 'backup int' option. If you are permitting all IP traffic as interesting traffic, then when the serial int goes down the BRI should come up immediately if you have dynamic routing protocol running across the BRI int.

If you have no dynamic routing protocol running then you could configure the rtr (SAA) scheduler to ping the far end BRI IP address (dialer-map IP). It's easy to set it up. See the link below for configuration guidance.

http://www.cisco.com/en/US/products/sw/iosswrel/ps1831/products_configuration_guide_chapter09186a00800ca63e.html#1001466

Configuring SAA wouldn't initiate the ISDN connection under normal circumstances as the BRI will be in admin down status when the serial interface is up.

Regards,

Sundar

[bapatsubodh]

Hi,

sundar.palaniappan

I am using backup interface command in serial interface configuration. But i am using a dialer as a backup interface and not BRI interface.

Like this

backup delay 10 10 ( in serial int conf )

backup int dialer 0 ( in serial int conf )

...

int dia 0

dialer string ( called number )

dialer-pool 1 ( member of Bri port interface )

access-group 1

dialer-list 1 prorotcol ip permit.

In this case can i make my dialer trigger even if there is no interesting traffic.

[sundar.palaniappan]

Hi,

Configure something like this. The router would attempt send ICMP packets to the remote ISDN interface address every 30 seconds. When the serial int goes down the dialer interface would come out of the standby state and the 'rtr' scheduler will trigger the ISDN to call out.

rtr 3

type pathEcho protocol ipIcmpEcho (remote_end_dialer_ip_address)

frequency 30

rtr schedule 3 start-time now life forever

Hope that helps!

Regards,

Sundar