Policy based routing??

[habbas.ali]

Hello

We have a Cisco 2600 router with a serial interface (64kb) and a adsl interface (512kb) for the connection to internet.

Is there any solution to send outgoing smtp traffic to the serial interface and the http traffic to adsl interface?

Can you please help me?

Thanks

[Richard Burts]

You have described a fairly simple requirement. And there is a fairly simple solution which should work. I would suggest that you configure the router with a default route pointing through the adsl interface. This will direct your http traffic (and other traffic as well) to the desired interface. Then I suggest that you configure Policy Based Routing to direct smtp to the serial interface. First configure an access list which will permit your smtp traffic. Then configure a route map such as

route map route_smtp permit 10

match ip address

set ip next-hop

Then configure the interface where the smtp traffic arrives with ip policy route_smtp

This should send http traffic through the adsl and send http traffic through the serial interface and satisfy your requirements.

If your requirements are really more complex, such as you want the serial interface to back up the adsl interface and all traffic should be sent through the serial interface if there is a failure of the adsl connection, then this is a more complex requirement and would require a more complex solution.

HTH

Rick

[habbas.ali]

Thanks a lot for your response Rick,

All work fine with your solution.

And now as you described, my client want the traffic send through serial when Adsl line fail.

Is is realy complex?

Can you help please

Thank you

[Richard Burts]

I am glad that my solution works fine for the original set of requirements. When you add the additional requirement that the serial interface must provide a backup for the Adsl line it does get somewhat more complex.

My original suggestion included configuring a default route pointing to the Adsl as the route to outside. Now we need to configure a floating static default route to supplement the original default route. The configuration might look something like this:

ip route 0.0.0.0 0.0.0.0 (this is the original default route)

ip route 0.0.0.0 0.0.0.0 serial0/0 50 (this is the floating static default route).

Under normal conditions the static default will be used and non-http traffic will be sent to Adsl. If the Adsl route fails then the floating static route will be put into the routing table and all traffic will be sent to the serial.

The reason that I say this will be more complex is in the question of what will cause the original default route to be withdrawn from the routing table. With the interface to Adsl it pretty much needs the interface protocol to go down before the route will fail. So there could be a problem in the Adsl device which causes traffic to fail but the interface on the router still thinks it is working. The solution for this is a new feature in IOS called Static Routes with Object Tracking. This will track availability of some remote IP address (perhaps some address in the provider network on or beyond the Adsl device) and if the remote address becomes not available then the static default route will be withdrawn. Look at this URL for an example

http://www.cisco.com/en/US/about/ac123/ac114/ac173/Q2-04/department_techtips.html

look particularly at Sample Config #2.

HTH

Rick