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PIX and Load Balancing when using PAT instead of NAT

zillah asked
Last Modified: 2013-11-16
We have two mail firewalls (Border Ware ) in the DMZ area, their ip addresses are and

 To implement load balancing (mails to be delivered to both of them in equal ) on these mail firewalls, I have been advised to use NAT for these two private ip addresses ( and to two different (not one) public ip addresses.

Since we have not got two much public ip addresses, my suggestion was to use PAT (not NAT),,,but when I use PAT can a PIX implement load balancing ?
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You could do it only if you have 2 public ip addresses. Then again, the pix will just make sure that either one of them or both of them send mails outside/inside. The load balancing theory is based off the whole setup.

Top Expert 2006

Assuming you balance mail delivery via equal costs in your MX records to the external public addresses.

There is nothing built into the pix hardware to do actual load balancing as renil said  using ospf or similar would allow for load balancing as would something along the lines of a cisco loaddirector or other load balancing hardware.

Cluster the mail servers together and redirect the inbound to a virtual ip .
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