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Community Member

isdn backup with black out period

I have an ISDN line configured as a backup interface for a frame circuit. I need to stop the interface from dialing during non-business hours. I have configured time-range and see that become active and block the requested traffic. But this doesnt stop the line from dialing.

5 REPLIES
Community Member

Re: isdn backup with black out period

Greetings:

Are you running a routing protocol over the ISDN line such as OSPF? If you are able to be in enabe mode when the line comes up, do a sh dialer to see what is causing the isdn line to become active. The line dials based on what interesting traffic traverses the isdn link, and also how your backup interface is configured.

Community Member

Re: isdn backup with black out period

Yes, both Decnet and ISIS are running and specified as interesting traffic. Due to high avalibility requirements. The backup int is configured under the Sub with minimal delay. We use EEK on the frame. Basically the backup is working as required, except I'd like to specify a black out period over the weekend.

Silver

Re: isdn backup with black out period

The only way I have seen this work is to use dial-on-demand routing to drive the backup and time-based access lists to define interesting traffic. Neither backup interface nor dialer watch use access-lists to define the need to dial, so there is no way to control their actualization based on time of day.

Since you need the link to come up regardless of whether or not there is traffic, you will need to use BGP to generate the interesting traffic used to force the dialing. Your IS-IS and DECnet routing traffic must be declared not-interesting or the link will never drop. The technique of using BGP to create interesting traffic on demand is described in a white paper on my web site and in Chapter 5 of my book High Availability Networking with Cisco.

Disclaimer: Response to link outages which do not force the interface down, as may occur on frame relay links unless end-to-end keepalives are used (which I assume you are doing, since you use backup interface), can be delayed by up to one minute because static routes are only updated during per minute processing on Cisco routers unless an interface changes state.

Good luck and have fun!

Vincent C Jones

www.networkingunlimited.com

Community Member

Re: isdn backup with black out period

Using the time-range statement and specifying the periodic for a given day, I can see the access list in the active state and blocking specified traffic during the schedule black out. Except it doesnt stop the backup from dialing. Here is an example. Maybe there is more?

access-list 111 permit ip any any log time-range DIALBK

!

dialer-list 1 protocol ip list 111

!

time-range DIALBK

periodic Monday 7:00 to 19:00

periodic Tuesday 7:00 to 19:00

Silver

Re: isdn backup with black out period

You don't want to BLOCK the traffic, if properly configured backup interface will bring up the ISDN line regardless of the traffic level.

You want to make the dial link demand driven so you can define all traffic as uninteresting during the blackout period. That way, the link will not come up during the blackout period and if up at the start, will drop after the idle timeout. Go back and reread my previous message keeping in mind how dial on demand works compared to backup interface compared to dialer watch.

Vincent C Jones

www.networkingunlimited.com

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