IKE_SA_INIT:
This is the first exchange in IKEv2. It establishes a secure, authenticated channel between peers and
negotiates cryptographic algorithms and keys.
IKE_Auth:
The second exchange authenticates the IKE SA (Security Association) using the previously negotiated
keys and algorithms. This exchange also establishes the first IPsec SA.
Create_CHILD_SA:
This exchange creates additional IPsec SAs after the initial authentication. It can also be used to rekey
existing IPsec SAs to maintain security.
Informational:
This is a generic exchange used for various purposes such as error notification, deletion of SAs, and
other control messages.
Reference:
Fortinet Community: IKEv2 packet exchanges and troubleshooting
Fortinet Documentation: IPsec VPN Concepts
