I would like to know if the following scenario is possible and what do you think I have to attend.
We have an email server inside our LAN that uses the biggest part of our incoming bandwidth of an ADSL connection (many incoming requests). We would like to distribute the incoming requests and create a fault tollerant (ISP independent) system. So we are thinking to buy another ADSL connection from different ISP, an additional pool of public IP addresses and a HWIC ADSL card for our 2811 Cisco Router. Between Cisco Router and LAN we have a Cisco ASA 5510 firewall that does NAT for our network. The router's interfaces will be configured with public IP addresses. The first ADSL interface will have public IP address from first ISP. The second ADSL interface will have public IP address from second ISP. The internal interface will be configured with two public IP addresses one from each ISP. ASA's external interface will be configured with two Public IP addresses (one from each ISP) and the inside interface will have private IP. The mail server will have a private IP address in our LAN. We will configure two A and PTR records in an external DNS pointing in the two Public IPs (one from each ISP) that we will dedicate for mail server.
Is this configuration possible through ASA firewall and Cisco 2811 router?
How I must configure ASA and Router?
Thanks in advanced.