PAT w/ a Pool 1

By certskills July 11, 2016 09:05

Configuring #PAT with a pool of inside global addresses combines most everything you can possibly configure with NAT in a Cisco router. Take a look at the requirements in this latest lab and put together your own configuration, with a pool and with PAT multiplexing connections using port numbers.


Configure PAT to support hosts in the subnet off R1’s G0/1 interface, for instance, for inside hosts like S1, S2, and S3. Use the following specific rules:

  • Match all inside addresses using a numbered ACL (ACL 1)
  • Configure a NAT pool called nat_pool, have the pool use the IP address using the associated interface subnet mask
  • Configure a PAT statement to use ACL 1 and the configured nat_pool for outside communications to R2
  • Configure static routes as needed on R2 so that R2 can forward packets back to these inside global addresses
  • Assume all router interfaces shown in the lab are up, working, and configured with IP addresses


Figure 1: PAT Topology (CL129.jpg)

Initial Configuration

Example 1 and 2 show the beginning configuration state of R1 and R2.

Example 1: R1 Config

Example 2: R2 Config


Answer on Paper, or Maybe Test in Lab

Next, write your answer on paper. Or if you have some real gear or other tools, configure the lab using them.

To test your solution if you happen to try it with VIRL or real gear, you can verify the PAT configuration by checking the reachability of R2 from PC1, PC2, or PC3 using the ping command. After these pings have been issued, you can check which addresses where assigned by using the show ip nat translations command on R1 or verify the PAT configuration and status by using the show ip nat statistics command. Or telnet from a PC to router R2. To do that, you might need to add the commands line vty 0 15, transport input all, login, and password cisco to set up simply password security and enable Telnet on router R2.

Do this Lab with Cisco’s VIRL

You can do these labs on paper and still get a lot out of the lab. As an extra help, we have added files for the Virtual Internet Routing Lab (VIRL) software as well. The .VIRL file found here is a file that when used with VIRL will load a lab topology similar to this lab’s topology, with the initial configuration shown in the lab as well. This section lists any differences between the lab exercise and the .VIRL file’s topology and configuration.

Download this lab’s VIRL file!

All interfaces in topology match the lab figure.

Network Device Info:

The switch used in the lab is an unmanaged switch.

Host device info:

This table lists host information pre-configured in VIRL, information that might not be required by the lab but may be useful to you.


IP Address








Handy Host Commands:

To see PC IP address: ifconfig eth1

Ping example: ping -c 4

Trace example: tracepath10.1.1.1

To connect to another node within the topology: telnet


Answers: L2 EtherChannel 2
Answers: PAT w/ a Pool 1
By certskills July 11, 2016 09:05
Write a comment

No Comments

No Comments Yet!

Let me tell You a sad story ! There are no comments yet, but You can be first one to comment this article.

Write a comment
View comments

Write a comment

Comment; Identify w/ Social Media or Email


Subscribe to our mailing list and get interesting stuff and updates to your email inbox.

Thank you for subscribing.

Something went wrong.