NAT will use a 1 to 1 translation. ie:
10.1.1.1 to 125.25.1.10
10.1.1.2 to 125.25.1.11
PAT will use source port substitution to keep track of inside address conversations. ie:
10.1.1.1 sp=1024 dp=80 to 125.25.1.10 sp=4092 dp=80
10.1.1.2 sp=1024 dp=80 to 125.25.1.10 sp=4093 dp=80
When packets come back from the destination to 125.25.1.10, PAT will look at the (sp and dp flip on the return trip) dp to translate back to the proper inside address. ie: packet comes back to 125.25.1.10 dp=4092, PAT translates to 10.1.1.1 and sends it to the inside.
Mick.
