Dial backup for FR link

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Jun 7th, 2003
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I have 3662 central router and 150 branched on FR links HUB and spoke config.

branche routers will only have default route to the HO router.


Requirement:

I need PSTN dial ackup for the FR link.

Also, I need the dial backup link to be kept activated irrespective of the interesting traffic. I need the backup linkto stay up untill primary FR link comes back.


I am trying with dialer-watch to watch the default route. I also defined a static default route with higher ad. distance to router traffice in the dial-back scenario.

This method has two problems.

1. Once the primary ois down, backup link is activated, but after short duration, the line is reset and re-dials.


2. If the primary link is down when the router powered- on. Then the routing table has static default route, hence router wil never dials to initiate the connection.


What is the best method to achieve the requirements ?

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tepatel Sat, 06/07/2003 - 17:51
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  • Cisco Employee,

The dialer-watch method should work fine with your requirements. We need to know what the PSTN links (analog or isdn) went down and re-dials. "debug dialer" will show us the reason for that.


Dialer-watch should not keep the pstn link up regardless of inetresting traffic and even if the idle-timeout expires. It will only bring down the backup link is the watched route learned via primary link.

visit following link for more

http://www.cisco.com/warp/public/123/backup-main.html#dwatch

Now, 2nd point, the backup link should be activated regardless of default route as dialer-watch works on watched routes. So we need to debug that issue.

Here is the link which compares all the backup methods

http://www.cisco.com/warp/public/123/backup-main.html

nkariyawasam Sun, 06/08/2003 - 04:10
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For the second point, what I Learned is , when I define the router to be watched is the defalut route ( 0.0.0.0/ 0.0.0.0 ) and do not want to run routing prorocol over the backup link I have the following defalut rotute defind;


ip route 0.0.0.0 0.0.0.0 172.16.50.2 150


When the router powers up, if the promary link is down, when I query teh route table I can see the floating static defalut route has been installed irrespective of the backup link UP/DOWN as follows;


172.16.0.0/16 is variably subnetted, 3 subnets, 2 masks

C 172.16.150.0/24 is directly connected, FastEthernet0

C 172.16.200.0/30 is directly connected, Loopback1

C 172.16.50.0/30 is directly connected, Async5

S* 0.0.0.0/0 [150/0] via 172.16.50.2


Therefore , I bilieve that the router "thinks" that the route to be watched, now via the static route , as the PRIMARY link.


Since dialer watch assumes that the "PRIMARY" link is UP, it is never going to dial.

Any thoughts ?

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