ZyXEL Communications 2602HW Series User Manual

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Prestige 2602HW Series User’s Guide
Chapter 16 Introduction to IPSec
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16.2  IPSec Architecture
The overall IPSec architecture is shown as follows.
Figure 83   IPSec Architecture
16.2.1  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 
16.2.2  Key Management
Key management allows you to determine whether to use IKE (ISAKMP) or manual key 
configuration in order to set up a VPN.
16.3  Encapsulation
The two modes of operation for IPSec VPNs are Transport mode and Tunnel mode.