ZyXEL Communications P-661H Series User Manual

 Chapter 12 VPN Screens

P-661H/HW Series User’s Guide

There are two phases to every IKE (Internet Key Exchange) negotiation – phase 1 
(Authentication) and phase 2 (Key Exchange). A phase 1 exchange establishes an IKE SA and 
the second one uses that SA to negotiate SAs for IPSec.

Figure 109   Two Phases to Set Up the IPSec SA

In phase 1 you must:

• Choose a negotiation mode.
• Authenticate the connection by entering a pre-shared key.
• Choose an encryption algorithm.
• Choose an authentication algorithm.
• Choose a Diffie-Hellman public-key cryptography key group (DH1 or DH2).
• Set the IKE SA lifetime. This field allows you to determine how long an IKE SA should 

stay up before it times out. An IKE SA times out when the IKE SA lifetime period expires. 
If an IKE SA times out when an IPSec SA is already established, the IPSec SA stays 
connected.

In phase 2 you must:

• Choose which protocol to use (ESP or AH) for the IKE key exchange.
• Choose an encryption algorithm.

Authentication 

Algorithm

Select SHA1 or MD5 from the drop-down list box. MD5 (Message Digest 5) and 

SHA1 (Secure Hash Algorithm) are hash algorithms used to authenticate packet 

data. The SHA1 algorithm is generally considered stronger than MD5, but is 

slower. Select MD5 for minimal security and SHA1 for maximum security. 

Advanced

Click Advanced to configure more detailed settings of your IKE key 

management. 

Apply

Click Apply to save your changes back to the ZyXEL Device.

Cancel

Click Cancel to begin configuring this screen afresh.

Table 78   Edit VPN Policies