ISDN backup for IPSec using Static Routes

Unanswered Question
Aug 24th, 2007

Hi,

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 (192.168.42.0 /24) as it uses a Default route (0.0.0.0) 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 192.168.42.0 (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 10.10.10.1 255.255.255.252 (example)

ip route 0.0.0.0 0.0.0.0 124.124.124.1 (default route on Hub via ISP router)

PARTNER-1 REMOTE ROUTER

===================

interface Dialer2

description ISDN Backup Link to HUB

ip address 10.10.10.2 255.255.255.252 (example)

ip local policy route-map ROUTING-POLICY

ip route 0.0.0.0 0.0.0.0 Dialer0 track 123 (DSL interface)

ip route 0.0.0.0 0.0.0.0 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 192.168.42.0 to be used ONLY when the ISDN is active on the Hub router.?

Thanks

John

I have this problem too.
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sundar.palaniappan Fri, 08/24/2007 - 16:02

On the hub router;

1. Configure a static route to 192.168.42.0 to point to 124.124.124.1 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 192.168.42.0 via 124.124.124.1.

2. Configure a floating static route (with a admin distance of 200) for network 192.168.42.0 to point to the next hop via ISDN or Dialer2 interface.

HTH

Sundar

john.pepper Fri, 08/24/2007 - 16:11

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 192.168.42.0 255.255.255.0 124.124.124.1 track xxx.xxx.xxx.xxx (remote DSL address)

many thanks

John

sundar.palaniappan Fri, 08/24/2007 - 16:35

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.

http://cisco.com/en/US/products/sw/iosswrel/ps5413/products_feature_guide09186a00801d862d.html

HTH

Sundar

maanav007 Sat, 09/08/2007 - 01:30

hi,

put this simple route

ip route 192.168.42.0 255.255.255.0 Dialer99 200

john.pepper Sun, 09/16/2007 - 12:01

Hi Sundar,

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

Many thanks for your help.

John

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