[c-nsp] Dialer Watch limited to time

[Oliver Boehmer (oboehmer)]

Gary Roberton <> wrote on Friday, January 20, 2006 1:08 PM:

> Hello All
> 
> We have end user dsl links connecting to a central router.  The
> central router has paths to multiple customers.
> 
> We need to do ISDN backup.  We cannot use normal dialers backing up
> the interface on the local site as it it possible that the path into
> the central router goes down.  We cannot have the central router with
> a back up dialer as the paths into it would not all go down at the
> same time so the interface would appear as up/up..
> 
> So, we have to use a dialer watch, watching an IP address on a
> loopback interface on the central router.  This all works fine but we
> want to restrict the dialer watch to only be allowed to dial up
> during business hours.  Does anyone know how to achieve this?

Well, since dialer watch does not require interesting traffic to bring
up the link, a time-based access-list commonly used as "dialer-list" in
regular DDR does not work in this case. 

You could, however, use a regular Dialer interface (with DDR) and a
time-based ACL and use the "Reliable Static Routing Backup Using Object
Tracking" feature
(http://www.cisco.com/en/US/products/sw/iosswrel/ps5413/products_feature
_guide09186a00801d862d.html#wp1071380) to activate the static
default-route to the Dialer when the connectivity goes down. So Object
Tracking activates the backup route, but the Dialer only dials during
business hours.

The alternative could be to implement the policy at the central ISDN
backup router, for example by using ISDN pre-authentication and only
accept the calls from the remote sites during business hours. In
off-hours the calls are rejected at ISDN layer so no call charges will
incur.

	oli