31 Days Before Your CCNA Exam

Day 5 305Use the debug ip nat command to verify the operation of the NAT feature by displaying informationabout every packet that the router translates, as shown in Example 5-6.Example 5-6Troubleshooting NAT with debug ip natR2#debug ip natIP NAT debugging is onR2#NAT: s=192.168.10.10->209.165.200.226, d=209.165.201.30[8]NAT*: s=209.165.201.30, d=209.165.200.226->192.168.10.10[8]NAT: s=192.168.10.10->209.165.200.226, d=209.165.201.30[8]NAT: s=192.168.10.10->209.165.200.226, d=209.165.201.30[8]NAT*: s=209.165.201.30, d=209.165.200.226->192.168.10.10[8]NAT*: s=209.165.201.30, d=209.165.200.226->192.168.10.10[8]NAT: s=192.168.10.10->209.165.200.226, d=209.165.201.30[8]NAT: s=192.168.10.10->209.165.200.226, d=209.165.201.30[8]NAT*: s=209.165.201.30, d=209.165.200.226->192.168.10.10[8]NAT*: s=209.165.201.30, d=209.165.200.226->192.168.10.10[8]NAT: s=192.168.10.10->209.165.200.226, d=209.165.201.30[8]R2#You can see that inside host 192.168.10.10 initiated traffic to outside host 209.165.201.30 and hasbeen translated into address 209.165.200.226.When decoding the debug output, note what the following symbols and values indicate:■■■■■*: The asterisk next to NAT indicates that the translation is occurring in the fast-switchedpath. The first packet in a conversation is always process-switched, which is slower. Theremaining packets go through the fast-switched path if a cache entry exists.s=: Refers to the source IP address.a.b.c.d->w.x.y.z: Indicates that source address a.b.c.d is translated into w.x.y.z.d=: Refers to the destination IP address.[xxxx]: The value in brackets is the IP identification number. This information may be usefulfor debugging because it enables correlation with other packet traces from protocol analyzers.