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Redundant Internet Connections on Cisco ASA 5505

I have dual ISP connections to my ASA with the monitor on the "outside" interface so that when it fails, it will switch to the second default route. This is great for outbound traffic.

I have an exchange server behind the ASA with the 192.168.X.X static of the Exchange box NAT'ed to one of the primary ISP's provided statics 51.2XX.XXX.XXX.

In the event of a failure of the primary ISP's WAN link, it would be nice if email would continue to flow to our Exchange server via he failover WAN link with a different group of static IP's. Is it okay to do that?

What I envision is adding an MX record with a higher value to the other routable static IP and then simply putting the NAT rule in for that.

Any suggestions on how best to do this?
1 Solution
Henk van AchterbergSr. Technical ConsultantCommented:
Your question has been asked here before but in a different context:


You can do what you would like to do, please take a look at the example config in the question above:

Pete LongTechnical ConsultantCommented:
Yep this is pretty normal, I've covered it here;
(See Point number 4)
Cisco ASA/PIX 8.x: Redundant or Backup ISP Links with VPNs

garyohAuthor Commented:
Guys, I sure appreciate this. Here's what I find at this point. My regular route is replaced as the default and the new route via the other ISP becomes the default route but no traffic is going out and my internet connection seems not alive. If I ping a known IP, it answers me so I know that part is working from the firewall upstream but from a pc inside the firewall. I don't have anything.

I thought the Access rules would need to be adjusted so I did notice there was no rule allowing data in so I just put an addttional rule in to allow all but it didn't get better.

What am I missing?
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