ZyXEL Communications P-661H Series - Manual (Page 199)

P-661H/HW Series User’s Guide
Chapter 12 Introduction to IPSec 199
12.2 IPSec Architecture
The overall IPSec architecture is shown as follows.
Figure 118 IPSec Architecture
12.2.1 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) 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. Please see
Section 13.2
on page 203 for more information.
12.2.2 Key Management
Key management allows you to determine whether to use IKE (ISAKMP) or manual key
configuration in order to set up a VPN.
12.3 Encapsulation
The two modes of operation for IPSec VPNs are Transport mode and Tunnel mode.