ZyXEL p-662h-61 Guia Do Utilizador

Prestige 662HW Series User’s Guide

Chapter 19 VPN Screens

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Figure 98   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.

• Choose an authentication algorithm

• Choose whether to enable Perfect Forward Secrecy (PFS) using Diffie-Hellman public-

key cryptography – see

. Select None (the 

default) to disable PFS.

• Choose Tunnel mode or Transport mode.

• Set the IPSec SA lifetime. This field allows you to determine how long the IPSec SA 

should stay up before it times out. The Prestige automatically renegotiates the IPSec SA 
if there is traffic when the IPSec SA lifetime period expires. The Prestige also 
automatically renegotiates the IPSec SA if both IPSec routers have keep alive enabled, 
even if there is no traffic. If an IPSec SA times out, then the IPSec router must renegotiate 
the SA the next time someone attempts to send traffic.

The phase 1 Negotiation Mode you select determines how the Security Association (SA) will 
be established for each connection through IKE negotiations.