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Figure 78 firewall: threshold, Table 54 firewall: threshold – ZyXEL Communications ADSL VoIP IAD with 802.11g Wireless 2602HW Series User Manual

Page 189

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Prestige 2602HW Series User’s Guide

Chapter 14 Firewall Configuration

189

Whenever the number of half-open sessions with the same destination host address rises above
a threshold (TCP Maximum Incomplete), the Prestige starts deleting half-open sessions
according to one of the following methods:

• If the Blocking Time timeout is 0 (the default), then the Prestige deletes the oldest

existing half-open session for the host for every new connection request to the host. This
ensures that the number of half-open sessions to a given host will never exceed the
threshold.

• If the Blocking Time timeout is greater than 0, then the Prestige blocks all new

connection requests to the host giving the server time to handle the present connections.
The Prestige continues to block all new connection requests until the Blocking Time
expires.

The Prestige also sends alerts whenever TCP Maximum Incomplete is exceeded. The global
values specified for the threshold and timeout apply to all TCP connections.

Click Firewall, and Threshold to bring up the next screen.

Figure 78 Firewall: Threshold

The following table describes the labels in this screen.

Table 54 Firewall: Threshold

LABEL

DESCRIPTION

DEFAULT VALUES

Denial of Service

Thresholds

One Minute Low

This is the rate of new half-open sessions that

causes the firewall to stop deleting half-open

sessions. The Prestige continues to delete

half-open sessions as necessary, until the

rate of new connection attempts drops below

this number.

80 existing half-open sessions.