Five Steps of IPSec Revisited

Step 1

Interesting traffic initiates an IPSec session—Access lists interpret IPSec security policy to determine which traffic will be protected by IPSec.

Step 2

IKE Phase One—IKE authenticates peers and negotiates IKE SAs to determine if a secure channel can be established between the peers.

Step 3

IKE Phase Two—IKE negotiates the stricter IPSec SA parameters between the peers.

Step 4

IPSec data transfer—Qualifying data is transferred between IPSec peers.

Step 5

IPSec tunnel termination—IPSec session terminates through deletion or by timing out.