what is the difference between nat traversal and nat exemption.

[donnie]

Hi all. In my site to site vpn connection both nat traversal and nat exemption are enabled. What is the difference between the 2 and why do i need both for my ipsec vpn to work. Thks in advance.

[lgijssel]

These are two different things.

isakmp nat traversal allows for VPN client traffic to be transported using the NAT-T feature.

nat exemption is what we use to not-NAT traffic that is sent over a VPN tunnel.

regards,

Leo

[Jon Marshall]

Hi

Just to expand on previous post.

Nat-traversal is needed when there is a device that sits somewhere in the path between your VPN devices that performs NAT on the packets.

Nat exemption is used to make sure that certain IP addresses are not subject to NAT and are left as is.

Jon

[hamedsol]

Then why we need nat between vpn devices at all?

[Richard Burts]

Sometimes the design of the network places a device using ipsec inside of a device that is doing address translation at the outside edge of the network. In this case we need nat traversal.