i have follow ing situation,
1.I have two different ISP and Two different public ip.
2.I have One cisco 1841 router and the router connected to ASA.
3.Nat is happening in ASA.
4.SMTP,WEB servers are nated in primary ISP IP.
Now i want to make high availablity network, if one ISP link is down second ISP will up and my servers accessible from outside. i need some sugestion
please find below diagram for reference.