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Community Member

How do i Configure ISDN backup for EtherNet0/0 on 3725 Route.

Hi Guys !

I have a Cisco 3725 Router with 2 ethernet interfaces and 4 BRI S/T interfaces. Ethernet0/0 is connected to Internet and Ethernet0/1 is connected to my LAN. I want to configure DDR so that whenever internet link via Ethernet0/0 is down router may automatically establish Backup link via ISDN dialup interface.

Solution, that so far, I have found is " Reliable Static Routing Backup Using Object Tracking " ......but I think this future is not available in 3725 router. Because when I try to configure this future as per directed in the manual, key commands are not availabe in my Router's IOS. My router is using " IOS (tm) 3700 Software (C3725 ADVIPSERVICESK9-M), Version 12.3(5a), RELEASE SOFTWARE (fc1) "

Please suggess me how do I configure DDR in my network scnario.

Waiting for your Warm & Quick response.

Thanx

6 REPLIES
Bronze

Re: How do i Configure ISDN backup for EtherNet0/0 on 3725 Route

Indeed, the feature you mention is only available in specific code releases for the 1700 series. Apparently it'll make it's way into the next 12.3T release, but I don't know how long from now that's going to be.

Though it's not an optimal way of doing things, you could use this feature: http://www.cisco.com/en/US/products/sw/iosswrel/ps5207/products_feature_guide09186a00801d1e95.html

You can configure the router to policy route everything out e0/0 unless e0/0's next-hop can't be pinged, at which point it sends traffic out the ISDN interface.

Silver

Re: How do i Configure ISDN backup for EtherNet0/0 on 3725 Route

While your problem statement lacks details, if your Ethernet link is to a "real" ISP, you should be able to get reliable backup the old fashioned way... running BGP with your ISP to detect loss of Internet connectivity and using Dial On Demand Routing and floating static routes to bring up the ISDN backup. You don't need much memory or CPU horsepower to accept just a default route.

On the other hand, if your Ethernet link is to a cable or DSL modem, you're probably out of luck with current Cisco kit. What you could do is run a script on a Unix/Linux/Windows box (or two, just in case) which pings or otherwise tests for upness, and pings an address which brings up the backup link if the test pings start failing.

Good luck and have fun!

Vincent C Jones

www.networkingunlimited.com

Community Member

Re: How do i Configure ISDN backup for EtherNet0/0 on 3725 Route

hi Tbaranski

Hope you are fine & doing well. Yes you are right, this feature can also work for me. But bad luck is that, this feature is also not available in my router's IOS.

I can create Tracking Object but cannot integrate that tracked object with Policy based routing. Following command is not available in my Router's IOS.

set ip next-hop verify-availability 10.1.1.1 10 track 123

in the above command " track 123 " object being tracked by PBR. This I cannot configure in my Router because in my router command ends up at

set ip next-hop verify-availability 10.1.1.1

Secondly for this feature to work properly the object being tracked should be running CDP ( Cisco Discovery Protocol). My ISP is not even providing Dynamic Routing protocol for Stub Networks, as mine, and CDP is far away.

If my ISP provides me Dynamic Routing Protocol then I can solve this issue with Dialer watch.

Bronze

Re: How do i Configure ISDN backup for EtherNet0/0 on 3725 Route

The PBR tracking feature was introduced in 12.3(4)T, so you'll need either that release or one of the newer 12.3(T) releases. I should have mentioned this originally.

Note also that PBR tracking via SAA doesn't require CDP. CDP can be used for tracking if desired, but SAA is a newer (and better) option.

Community Member

Re: How do i Configure ISDN backup for EtherNet0/0 on 3725 Route

hi Tbaranski...

Thank you for your urgent response. You have driven me towards a good point, as you said in your response " so you'll need either that release or one of the newer 12.3(T) releases. "

hmmmm....this might be point of failur in configuring PBR because current IOS that my router is running is " (C3725-ADVIPSERVICESK9-M), Version 12.3(5a) ". So let me get 12.3(T) and will let u know....

Am I right Tbaranski?

Bronze

Re: How do i Configure ISDN backup for EtherNet0/0 on 3725 Route

Right -- you'll need a 12.3T release, either 12.3(4)T or newer.

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