Zhone 2000 ユーザーガイド

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following) on this IAD as shown in Figure 4.33. Otherwise, the IAD 
displays the WAN port table and prompts you to select a port.
2
Type the port number on which to enable NAT and press Enter. The IAD 
prompts you to enable or disable NAT.
3
Type “E” to enable NAT, or “D” to disable. The IAD saves the setting and 
displays the NAT Configuration menu.
4
Continue with other NAT configuration tasks, or press Escape to return to 
the Main menu.
Configure NAT TCP and UDP Timeouts
Under normal circumstances, the timeout default setting is adequate. 
However, if users interact with products including multiple-player IP games 
or video conferencing, you may need to configure the timeout.
The local server protocol you select determines which timeout to configure. 
TDP and UDP are similar, except that TCP tracks TCP clients on a per-
connection basis and removes them from the table as soon as the connection 
closes.
To configure a NAT timeout, follow the steps below.
1
On the NAT Configuration menu, type “T” to select TCP connections, or 
type “U” to select UDP connections. The IAD displays a TCP or UPD 
prompt.
2
Type the timeout value and press Enter. The IAD displays the NAT 
Configuration menu.
3
Continue with other NAT configuration tasks, or press Escape to return to 
the Main menu.
4
Reset the IAD.
Configure NAT Port Range
The size of the NAT port range defines the number of simultaneous 
connections permitted. A small port range limits the number of connections. 
Since the range that you assign must be outside the range of assigned ports, 
do not set port ranges below 5,000.
Under normal circumstances, the port range default setting is adequate. 
However, if you interact with products including multiple-player IP games or 
video conferencing, you need to configure the port range setting.
To multiplex several connections to a single destination, the IAD assigns all 
packets unique port numbers. Each IP packet starts with a header that contain 
the source and destination addresses, as well as two port numbers. The 
addresses specify the two routers at each end, while the two port numbers 
ensure the unique identification of each router pair.
When the IAD sends TCP or UDP connection from a local port to an Internet 
port, it changes the sent IP address to the address of the Internet port.