PAT vs NAT

NightShade03NightShade03 Member Posts: 1,383 ■■■■■■■□□□
So I seem to be having some confusion here...

I get the difference between PAT and NAT, but Juniper seems to over complicate where/when you would use each. Obviously NAT is for one to one, one to many, etc.....but in what instance would you use PAT?

Comments

  • networker050184networker050184 Mod Posts: 11,962 Mod
    NAT is one to one. PAT is many to one.
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  • NightShade03NightShade03 Member Posts: 1,383 ■■■■■■■□□□
    NAT is one to one. PAT is many to one.

    Hmmm maybe my Nat/pat understanding is off...thanks for the reply though
  • ZartanasaurusZartanasaurus Member Posts: 2,008 ■■■■■■■■□□
    Hmmm maybe my Nat/pat understanding is off...thanks for the reply though
    It's confusing b/c everyone calls it NAT when they usually mean PAT.

    There's Static NAT, Dynamic NAT and PAT (or NAT Overloading).

    Static NAT is a one to one mapping. Each private host consumes one external IP.

    Dynamic NAT is kind of like DHCP. You configure a pool of public addresses. Private hosts make a connection and the router hands out the first available public IP. Once the pool is filled, no more private hosts can be translated. When a connection goes stale, an IP is returned to the pool.

    PAT is what most people mean when they say NAT. Each private connection to the outside is mapped to a public IP + port combination. So even with one public IP, you could have several private hosts using the same public IP.

    Static = one to one
    Dynamic = many to many on a one to one basis
    PAT = one to many

    Most likely, you'd end up doing static (an internet facing server) or PAT (a group of client machines on a subnet).
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  • NightShade03NightShade03 Member Posts: 1,383 ■■■■■■■□□□
    Excellent clarification!! I noticed that Cisco refers to PAT as "overloading" which is probably why Juniper calling it PAT is confusing me. Makes a lot more sense now, just have figure out the Juniper specifics for configuration. Thanks.
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