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Order of NAT

sushil
Level 1
Level 1

Hi,

Wanted to know order of NAT from version 8.3 onwards.

Deocumentation says Section 1 Twice Nat

                                 Section 2 Network Object Nat

                                 Section 3 Twice Nat

By default twice nat falls in Section1 (Correct me if I am wrong). How come it also falls in Sections3 as well.Is it something like bypassing nat (more like Nat 0 of older versions) while configuring VPN?

Reg,

Sushil

1 Accepted Solution

Accepted Solutions

Shrikant Sundaresh
Cisco Employee
Cisco Employee

Hi Sushil,

The order of NAT in 8.3 and above is:

1. Manual Nat

2. Auto NAT

3. After-Auto

After auto, are Manual Nat's with the "after-auto" keyword in them. These are processed after Manual nat rules without that keyword, and auto nat.

syntax: nat (intf1,intf2) after-auto ....

An ideal scenario, where you would use this would be:

All statics configured using Auto NAT.

For some reason, interface pat for internet is to be done using manual nat.

If you use the class 1 manual nat, then it will break all the auto nat static forwards. Hence, you add after-auto, so that it is processed only after the statics are checked.

Hope this helps.

-Shrikant

P.S.: Please mark the question as answered if it has been resolved. Do rate helpful posts. Thanks.

View solution in original post

2 Replies 2

Shrikant Sundaresh
Cisco Employee
Cisco Employee

Hi Sushil,

The order of NAT in 8.3 and above is:

1. Manual Nat

2. Auto NAT

3. After-Auto

After auto, are Manual Nat's with the "after-auto" keyword in them. These are processed after Manual nat rules without that keyword, and auto nat.

syntax: nat (intf1,intf2) after-auto ....

An ideal scenario, where you would use this would be:

All statics configured using Auto NAT.

For some reason, interface pat for internet is to be done using manual nat.

If you use the class 1 manual nat, then it will break all the auto nat static forwards. Hence, you add after-auto, so that it is processed only after the statics are checked.

Hope this helps.

-Shrikant

P.S.: Please mark the question as answered if it has been resolved. Do rate helpful posts. Thanks.

Ultimate discription Shrikant.Thanks a ton.

Reg,

Sushil

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