Directional route-maps

[lostnetworker]

Hi,

Is it possible to configure route-maps on an interface and route only specific incoming traffic (e.g smtp packets)to a specific destination and leave all else as default?

If I create an access-list that defines smtp traffic and apply it to a route-map and then onto an interface, I believe it would route all smtp traffic to that IP no matter which direction it is coming from.

Any ideas?

Thanks in advance

[thisisshanky]

Yes what u trying to do can be achieved by policy routing.

http://www.cisco.com/en/US/products/sw/iosswrel/ps1828/products_configuration_guide_chapter09186a00800ca590.html

[lostnetworker]

Hi shanky,

Thanks. Will try it out. By the way, is it possible to let the route-map activate based on state? like on failover ?

[tbaranski]

It's possible, and there are a few different ways to do it depending on how your network is set up. If you're policy routing out an interface that will change state to 'down' upon a failure (e.g., a point-to-point circuit such as a T1), policy routing can detect the interface going down and either a) switch to a backup next-hop if you've configured more than one (e.g., set ip next-hop 1.1.1.1 2.2.2.2), or b) revert to standard destination-based routing if only a single next-hop is configured.

Things get a bit more complicated if the interface remains 'up' during a failure, as is usually the case with Ethernet. Here, you need to use an active method of failover such as CDP (via the 'verify-availability' keyword in the policy routing configuration), or better yet, ping-based policy routing via the following new feature as of 12.3(T): http://www.cisco.com/en/US/products/sw/iosswrel/ps5207/products_feature_guide09186a00801d1e95.html

[lostnetworker]

Hi tbaranski,

Currently I have a route-map with the first statement as deny and the second as permit.

The deny statement denies ip addresses available on normal state. Therefore policy routing should only take place when the 'main' ip addresses are no longer available

This should work?

[tbaranski]

I don't think this will accomplish what you want, but I may not be understanding you completely. If you can post the relevant config portions along with what you're trying to do, it may clear things up.

[lostnetworker]

Hi

Unfortunately I am unable to get a copy of the configurations at the moment. I will post it up when I do.

I actually need an email server to be active at all times. I have 1 main WAN link and 1 ISDN DDR link. Therefore my email server's internal IP needs to be NAT'd through both IP addresses depending on which link is up

Anyway to go through this using NAT? I can't seem to find it which is why i am looking at route maps