How can I configure my ASA for 2 ISPs each with different IP address range allocated to us

[Richard Bradfield]

We have had a single ISP for years with a  public address space 203.xx.xx.xx/24, now we have just got another ISP with a 220.xx.xx.xx/28 address space

now when I  do my natting I obviously want the appropriate public address to go thru to the correct ISP. if I could do route maps as per a router there would be no problems, also not allowed to put 2 default routes(0.0.0.0 0.0.0.0) on the ASA . can this be achieved on a single ASA?

[Karsten Iwen]

You have to configure both ISPs in a primary/backup-way for outgoing traffic. For incoming traffic, both ISPs can be used at the same time. You need:

1. A default route to your primary ISP with tracking
2. A default route to your backup ISP with a higher AD
3. complete NAT-configs for both ISPs

A Guide for ASA version 7 is found here:

http://www.cisco.com/c/en/us/support/docs/security/pix-500-series-security-appliances/70559-pix-dual-isp.html

Just change the NAT to the new syntax for ASA version >=8.3.

[Richard Bradfield]

 That's not what I want, as I have two different Public address ranges I need to be able to send thru each ISP concurrently. Servers have specific Public addresses so must go to the correct ISP network, because of routing from the Internet.

[Karsten Iwen]

The ASA doesn't support policy-based routing. You should place a router in front of the ASA to do the prober routing.