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Community Member

Varying the ISP dialed-up number dependent on time of day

Hi. Can anyone help me? I can't see how to get my 12.0(5)T 803 to route to the same ISP but using different access numbers for during office hours or out of office hours. (The ISP is charging different tarrifs.) I have defined time-ranges ok and extended access lists ok, but how do I apply these to one dialer interface? Do I need two dialer-strings or how to vary it dependent on the time of day? (Or do I have to have more than one dialer interface?) If so, I only have a static default route and no routing protocol running - what happens to that? Anyone can help I'd be grateful. Owen


Re: Varying the ISP dialed-up number dependent on time of day

I think you might be able to do this using timed access lists--I've never actually tried it, of course, but it seems like a reasonable place to start.



Community Member

Re: Varying the ISP dialed-up number dependent on time of day

Hi Russ. Thanks for the reply. I don't know what timed access-lists are. I saw on CCO: and got the following:


There are many possible benefits of time ranges, such as the following:

When provider access rates vary by time of day, it is possible to automatically reroute traffic cost effectively."

This is exactly what I want. This page also states that:

"It is now possible to implement access lists based on the time of day. To do so, you create a time range that defines specific times of the day and week. The time range is identified by a name and then referenced by a function, so that those time restrictions are imposed on the function itself."

IMPORTANT>>> "Currently, IP and IPX extended access lists are the only functions that can use time ranges. The time range allows the network administrator to define when the permit or deny statements in the access list are in effect. Prior to this feature, access list statements were always in effect once they were applied. Both named or numbered access lists can reference a time range."

So, I've set up two time-ranges:

time-range outhour

periodic weekend 0:00 to 23:59

periodic weekdays 18:00 to 23:59

periodic weekdays 0:00 to 8:00


time-range inhour

periodic weekdays 8:00 to 18:00

and I've applied these to extended access-lists:

access-list 101 permit ip any any time-range inhour

access-list 105 permit ip any any time-range outhour

OK - so good so far, and if I apply each individual access list to the dialer interface, it will permit during the specified time-range and implicit deny at all others - so I've got the time-range defintion working.

But - I need to apply these access-lists to the dialer interface such that, as a function of the different time-ranges, a different dialer string is dialed. I just can't see how to do it although it clearly says it can be done. (If I change the dialer, then I have to change the static route too, so I don't wnat to have to do this I guess.)

If you can help me further, it would prevent any further hair loss of mine! Thanks for listening. Owen

Community Member

Re: Varying the ISP dialed-up number dependent on time of day


Yes you are on the right track.

Create a time based accesslist, create two Dialer Interfaces with the correct access-list triggering the correct Dialer interface. Then create two default routes to each dialer interface with different distance, for example:

ip route dialer1

ip route dialer2 50

I have never done this but I think it's worth trying.

Another thing to look at is to try to find solution using route-map's.

One problem I can see in the solution with the two dialers is that dialer interface is always up, so the solutin with the two default routes may not work as expected. In that case make default route to the physical interface.

Hope this helps

Community Member

Re: Varying the ISP dialed-up number dependent on time of day

Hi there and thank you.

I tried the two dialers with different distance and, like you suggested, because di1 is up, it takes precedence. The access-list then simply denies traffic. If I put the default route onto BRI0, then the encapsulation fails (although set to ppp)

If I try to configure BRI0 like the dialer interface, I then have to remove the other dialers that are in the dialer pool. So, I'm still not there. Any other ideas or what am I doing wrong? Owen

Community Member

Re: Varying the ISP dialed-up number dependent on time of day


Here is what you can do to avoid this situation. Ask the ISP if they can supply you with static IP when you dial into them. That way you can use the conf with the two dialers that are triggered by the time based access lists and have the default route pointing to the the address that will always be supplied to you based on the username with which you are dialing into your ISP. But this will require cooperation with the ISP. It can be done since we do it. So your default route will be something like this

ip route a.b.c.d where a.b.c.d is the address that will be assigned to you by your ISP.

I cant think of anything else at this time. But I'm sure that some more experienced Cisco staff should be able to help you.

Hope this helps


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