ZyXEL Communications ZyXEL ZyWALL P1 - Manual (Page 126)

ZyWALL P1 User’s Guide
Chapter 8 Introduction to IPSec 125
8.2 IPSec Architecture
The overall IPSec architecture is shown as follows.
Figure 49 IPSec Architecture
8.2.1 IPSec Algorithms
The ESP (Encapsulating Security Payload) Protocol (RFC 2406) and AH (Authentication
Header) protocol (RFC 2402) describe the packet formats and the default standards for packet
structure (including implementation algorithms).
The Encryption Algorithm describes the use of encryption techniques such as DES (Data
Encryption Standard), AES (Advanced Encryption Standard) and Triple DES algorithms.
The Authentication Algorithms, HMAC-MD5 (RFC 2403) and HMAC-SHA-1 (RFC 2404,
provide an authentication mechanism for the AH and ESP protocols. Refer to
Section 9.2 on
page 129 for more information.
8.2.2 Key Management
Key management allows you to determine whether to use IKE (ISAKMP) or manual key
configuration in order to set up a VPN.
8.3 Encapsulation
The two modes of operation for IPSec VPNs are Transport mode and Tunnel mode.