ZyXEL Vantage CNM User Guide - Page 481

Chapter 20 VPN Community Table 211 VPN Management > VPN Community > Add/Edit (continued) FIELD DESCRIPTION SA Life Time (Seconds) Define the length of time before an IKE SA automatically renegotiates in this field. It may range from 180 to 3,000,000 seconds (almost 35 days). Key Group Select which Diffie-Hellman key group (DHx) you want to use for encryption keys. Choices are: DH1 - use a 768-bit random number Enable Multiple Proposals DH2 - use a 1024-bit random number Select this to allow the Vantage CNM to use any of its phase 1 key groups and encryption and authentication algorithms when negotiating an IKE SA. When you enable multiple proposals, the Vantage CNM allows the remote IPSec router to select which phase 1 key groups and encryption and authentication algorithms to use for the IKE SA, even if they are less secure than the ones you configure for the VPN rule. Phase 2 Active Protocol Clear this to have the Vantage CNM use only the configured phase 1 key groups and encryption and authentication algorithms when negotiating an IKE SA. Select the security protocols used for an SA. Encryption Algorithm Both AH and ESP increase processing requirements and communications latency (delay). Select which key size and encryption algorithm to use in the IKE SA. Choices are: DES - a 56-bit key with the DES encryption algorithm 3DES - a 168-bit key with the DES encryption algorithm NULL - no encryption key or algorithm AES - a 128-bit key with the AES encryption algorithm Authentication Algorithm SA Life Time (Seconds) The Vantage CNM and the remote IPSec router must use the same algorithms and keys. Longer keys require more processing power, resulting in increased latency and decreased throughput. Select which hash algorithm to use to authenticate packet data in the IPSec SA. Choices are SHA1 and MD5. SHA1 is generally considered stronger than MD5, but it is also slower. Define the length of time before an IPSec SA automatically renegotiates in this field. The minimum value is 180 seconds. A short SA Life Time increases security by forcing the two VPN gateways to update the encryption and authentication keys. However, every time the VPN tunnel renegotiates, all users accessing remote resources are temporarily disconnected. Vantage CNM User's Guide 481