Using "overload" command with PAT

Codeman6669Codeman6669 Posts: 227Member
Hey guys

So i noticed in one of my books, they were setting up dynamic NAT. But then they used the command "overload" when they have pool of 3+ public IP's

Is this correct? Can you use a pool of multiple public IP's and still use the overload command? Or is that only done when you only have one public IP?


  • streetkingstreetking Posts: 12Member ■□□□□□□□□□
    You can totally use a pool of public ip to do dynamic nat. Heck you will have to if you have thousands of hosts that have Internet access because you will eventually run out of ports for natting. Imagine you have one host that opens a website and the browser issued double digits amount of http get requests because the site links its content here and there. How many hosts will it take to saturate 65535 minus1024 natted ports and everyone starts dropping sessions prematurely?
  • Codeman6669Codeman6669 Posts: 227Member
    Totally make since, thanks for responding.
    For some reason my **** teacher told us you only use PAT with a single public IP. I sometimes wish i had just bought the book and studied rather than taking his class.

    Thanks again!!
  • RouteMyPacketRouteMyPacket Posts: 1,104Member
    And your teacher is right, go back and read the definitions of NAT and PAT.


    ip nat pool NAT prefix 24
    ip nat inside source list 1 pool NAT



    ip nat pool NAT prefix 24
    ip nat inside source list 1 pool NAT overload

    Of course there is more configs involved but these two show the difference
    Modularity and Design Simplicity:

    Think of the 2:00 a.m. test—if you were awakened in the
    middle of the night because of a network problem and had to figure out the
    traffic flows in your network while you were half asleep, could you do it?
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