Nat Question?

UsualSuspect7

Hey, Everyone!

I have a question pertaining to NAT can someone explain the differences between: Inside Global, Inside Local, Outside Local, and Outside Global.

I understand the Inside part.... well I think:

Inside Local would be the local IP assigned to the host. Then when the packet hit's the Nat router it's translated to the Inside Global to communicate on the internet with a public IP.


My question is what in the world is Outside Global, and Outside Local?

Is this the return traffic from the remote destination? or is it that the inside local get's translated at the incoming port on the router interface then becomes the inside global if it's on the company intranet, but when it leaves it becomes outside global?

networker050184

The example I like to use for these is a load balancer doing SNAT (Source NAT) for a website.

An HTTP request comes in from the internet with source IP 1.1.1.1 (outside global) and hits your LB destined to 2.2.2.2 (inside global) which is the VIP for your site.

LB translates the source to itself 3.3.3.3 (outside local) so that all return traffic goes to the LB and translates the destination to 4.4.4.4 (inside local) to send to one of the real servers.