My Internet Module Includes following devices: two cisco 3845, three 3750 one ASA 5540
They are connected as shown in figure (attachment).
Both internet routers and switch are meant for redundancy from different ISPs. ASA is having Dmz where mail and web servers has to be placed(i.e. static nat is required).
what will be the best possible way to make the servers (web and mail) available on the internet?
note: both the ISPs use different subnets and the ip of isp A is not routable in isp B.
wher should i NAT the global IPs ? on routers or ASA ?