Packet Tracer – Verifying and Troubleshooting NAT Configurations (Instructor Version)
Instructor Note: Red font color or Gray highlights indicate text that appears in the Answer copy only.
Topology
Addressing Table
Objectives
- Part 1: Isolate Problems
- Part 2: Troubleshoot NAT Configuration
- Part 3: Verify Connectivity
Scenario
A contractor restored an old configuration to a new router running NAT. But, the network has changed and a new subnet was added after the old configuration was backed up. It is your job to get the network working again.
Part 1: Isolate Problems
Ping Server1 from PC1, PC2, L1, L2, and R2. Record the success of each ping. Ping any other machines as needed.
Part 2: Troubleshoot NAT Configuration
Step 1: View the NAT translations on R2.
If NAT is working, there should be table entries.
Step 2: Show the running configuration of R2.
The NAT inside port should align with the private address, while the NAT outside port should align with the public address.
Step 3: Correct the Interfaces.
Assign the ip nat inside and ip nat outside commands to the correct ports.
R2(config)# interface Serial0/0/0
R2(config-if)# ip nat outside
R2(config-if)# interface Serial0/0/1
R2(config-if)# ip nat inside
Step 4: Ping Server1 from PC1, PC2, L1, L2, and R2.
Record the success of each ping. Ping any other machines as needed.
Step 5: View the NAT translations on R2.
If NAT is working, there should be table entries.
Step 6: Show Access-list 101 on R2.
The wildcard mask should encompass both the 10.4.10.0 network and the 10.4.11.0 network.
Step 7: Correct the Access-list.
Delete access-list 101 and replace it with a similar list that is also one statement in length. The only difference should be the wildcard.
R2(config)# no access-list 101
R2(config)# access-list 101 permit ip 10.4.10.0 0.0.1.255 any
Part 3: Verify Connectivity
Step 1: Verify connectivity to Server1.
Record the success of each ping. All hosts should be able to ping Server1, R1, and R2. Troubleshoot if the pings are not successful.
Step 2: View the NAT translations on R2.
NAT should display many table entries.
