ZyXEL 202H 91-003-194001B User Manual

P-202H Plus v2 User’s Guide

Chapter 11 VPN Screens

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When you initiate an IPSec tunnel with keep alive enabled, the ZyXEL Device automatically 
renegotiates the tunnel when the IPSec SA lifetime period expires (

 

for more on the IPSec SA lifetime). In effect, the IPSec tunnel becomes an “always on” 
connection after you initiate it. Both IPSec routers must have a ZyXEL Device-compatible 
keep alive feature enabled in order for this feature to work.

If the ZyXEL Device has its maximum number of simultaneous IPSec tunnels connected to it 
and they all have keep alive enabled, then no other tunnels can take a turn connecting to the 
ZyXEL Device because the ZyXEL Device never drops the tunnels that are already connected. 

Note: When there is outbound traffic with no inbound traffic, the ZyXEL Device 

automatically drops the tunnel after two minutes.

With aggressive negotiation mode (see 

), the ZyXEL Device 

identifies incoming SAs by ID type and content since this identifying information is not 
encrypted. This enables the ZyXEL Device to distinguish between multiple rules for SAs that 
connect from remote IPSec routers that have dynamic WAN IP addresses. Telecommuters can 
use separate passwords to simultaneously connect to the ZyXEL Device from IPSec routers 
with dynamic IP addresses (see 

 for a telecommuter configuration 

example).

Note: Regardless of the ID type and content configuration, the ZyXEL Device does 

not allow you to save multiple active rules with overlapping local and remote IP 
addresses.

With main mode (see

), the ID type and content are encrypted to 

provide identity protection. In this case the ZyXEL Device can only distinguish between up to 
eight different incoming SAs that connect from remote IPSec routers that have dynamic WAN 
IP addresses. The ZyXEL Device can distinguish up to eight incoming SAs because you can 
select between three encryption algorithms (DES and 3DES), two authentication algorithms 
(MD5 and SHA1) and two key groups (DH1 and DH2) when you configure a VPN rule (see 

). The ID type and content act as an extra level of identification for 

incoming SAs.

The type of ID can be a domain name, an IP address or an e-mail address. The content is the IP 
address, domain name, or e-mail address. 

Table 34   Local ID Type and Content Fields

IP

Type the IP address of your computer or leave the field blank to have the ZyXEL 

Device automatically use its own IP address.

DNS

Type a domain name (up to 31 characters) by which to identify this ZyXEL Device.