Now I want to talk about the two different phases that IKEv1 has.
They're named IKE phase 1 and IKE phase 2.
These two phases are the main pieces of the IPsec puzzle.
Once the interesting traffic is identified,
which is the traffic that we tell the device is
interesting based on our configurations,
the IPsec process starts and moves into phase 1.
It then goes into the second phase, and then the data is sent out.
Let's detail these a bit more so we can learn what each phase does.
So IKE phase 1; it's essentially the method that allows us to
negotiate the actual IPsec SAs securely.
During the phase 1 process, sometimes referred to as ISAKMP,
the IKE SAs are being established, and a secure tunnel is formed.
Remember when we were in the lab earlier in the course and we
used the command show crypto isakmp sa?
Yep, that was showing us the IKE phase 1 information.
It authenticates the identities of the IPsec devices,
negotiates the SA policies, and using the Diffie-Hellman algorithm,
the keys are exchanged securely to ensure that the devices have matching ones.
During phase 1, the tunnel is established,
which allows us to securely negotiate the IPsec parameters.
This phase has two modes, which we'll detail here in a little bit.
Speaking of IPsec parameters, this is where phase 2 comes into play.
Phase 1 builds the initial IPsec tunnels that are used to
establish the IPsec SAs within them.
Phase 2 is the negotiation and establishment of the
IPsec SAs that are being used.
This is where our actual IPsec tunnels are established based on the
security policies that we defined in the configuration.
Once the phase is over,
the packets that are identified as interesting will be
encrypted and decrypted as detailed in that policy. This phase only has one mode available, which we'll detail in a minute.