12.2. VPN Operation

Now you know about the components of IPsec and types of VPNs, so let's jump into how it all works. First, I discuss generic operation and then get more specifically into how it works in the Cisco environment.

Obviously, you've read about a lot of different technology, but in order to make this a little more palatable, I can generically describe IPsec in just a few tasks. So let's summarize what those tasks involve. Assuming you have an existing configuration:

  1. An IPsec process is started when traffic that is defined as interesting matches an existing policy.

    The interesting traffic is usually defined in terms of a source IP host or network and a destination IP host or network. This begins the IKE process.

  2. IKE Phase 1 is initiated. ...

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