When troubleshooting IPSec VPNs, it is important to adopt a step-by-step approach.
The first step in troubleshooting IPSec VPNs is to verify IKE phase 1 negotiation between the peer routers. Once this has been verified, the next step is to verify IKE phase 2. In the final step, you should verify that user traffic is being transported successfully over the IPSec tunnel.
The flowchart in Figure 8-13 describes the troubleshooting process used with IPSec VPNs. You can use this flowchart to quickly access the section of the chapter relevant to problems you are experiencing on your network.
Refer to the sample topology in Figure 8-14 for the various concepts discussed in the ...