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ISDN backup for IPSec using Static Routes


Can anyone help with this please?

We have a VPN with a hub router and 30+ remote sites. These are partner sites so standard IPSec (not GRE) with no routing protocol. Routing is done by static routes.

Recently one partner wants ISDN backup. We decided to use Object Tracking and we configured this on the remote partner router to ?track? the public IP address of our Hub VPN router. This works fine and fails over to ISDN when the DSL circuit fails or the route is lost to the tracked address. The ISDN comes up ok but the Hub router cannot route back to the remote subnet ( /24) as it uses a Default route ( which points via it?s ISP router ? so all traffic still routes this way.

We?ve tried adding various static?s by specifying the interface etc. and changing distance but with no success.

Can anyone offer any advice as to how we configure a route to (remote LAN subnet)on our Hub router so that it routes over the Dialer99 interface ONLY when the ISDN is active. When the ISDN is down all traffic should just go via the default route via the ISP.?

Relevant config bits as follows:

HUB ROUTER ISDN config for Partner site


interface Dialer99

description PARTNER-1 ISDN Backup

ip address (example)

ip route (default route on Hub via ISP router)



interface Dialer2

description ISDN Backup Link to HUB

ip address (example)

ip local policy route-map ROUTING-POLICY

ip route Dialer0 track 123 (DSL interface)

ip route Dialer2 254 (ISDN interface)

As can be seen above, the Hub router has only a Default route so sends traffic this way all the time. We need to know how we can specify a route to to be used ONLY when the ISDN is active on the Hub router.?




Re: ISDN backup for IPSec using Static Routes

On the hub router;

1. Configure a static route to to point to and track the DSL IP address of the remote site in the same statement. If the DSL IP becomes unreachable the router should remove the route to via

2. Configure a floating static route (with a admin distance of 200) for network to point to the next hop via ISDN or Dialer2 interface.



New Member

Re: ISDN backup for IPSec using Static Routes

Hey Sundar,

Many thanks for the fast reply.

Could you please clarify somehting - do I configure the track statement to the remote DSL interface in the same command or is there other commands required to do this..?

e.g. would this command work

ip route track (remote DSL address)

many thanks


Re: ISDN backup for IPSec using Static Routes

You would only specify the tracking object # in the static route. The tracked object configuration is done separately in the global configuration mode and that's where you would specify the remote DSL IP address to be polled.

Check the following link that lists the configuration procedure and contains a good number of examples.



New Member

Re: ISDN backup for IPSec using Static Routes


put this simple route

ip route Dialer99 200

New Member

Re: ISDN backup for IPSec using Static Routes

Hi Sundar,

Your suggestion worked and now we have a working solution using the tracking both ways.

Many thanks for your help.


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