2 Internet Connections 1 Router

[bfrawley]

I have a Cisco Router that i am going to be using to load balancing/failover between 2 ISP's. Where I am hitting a problem is with outbound NAT rules/IP Pools.

For example: From one of our ISP's our IP block is from 1.2.3.1 - 1.2.3.10 and the other is 2.3.4.1 - 2.3.4.10. When our email server communicates with the internet we want it to use 1.2.3.4 if it goes out ISP1 and 2.3.4.4 if it goes out ISP2.

I am currently using IP Pools and access lists to force traffic from our mail server to specifically use one or the other.

ip nat pool EmailServerPool 1.2.3.4 1.2.3.4 netmask 255.255.255.0
ip nat inside source list 101 pool EmailServerPool
access-list 101 permit ip host 192.168.1.4 any

The problem is if it were to failover to my other connection it would still be trying to use the IP address of the failed connection.

I think i need to use a route map somehow but i can't figure out how to get it to work. I am basically trying to say if the packet is coming from the IP address of our mail server and it is going out a specific interface NAT using this IP. If it is going out the other interface NAT using this IP.

Does this make sense?

 

[unclerico]

Are you making use of BGP between your providers??

I hate all Uppercase... I don't want my groups to seem angry at me all the time! =)
- ColdFlame (vbscript forum)

 

[bfrawley]

No. I am using CEF which from what I have found does basically round robin per connection.