3Com OfficeConnect Remote 812 manual continues to run until a NAT port frees up, used

6-20CHAPTER 6: MANUAL SETUP

PAT allows multiple private IP addresses to use one public IP address by dynamically and statically mapping each private IP source address and private IP source port to one public IP source address and one public IP source port.

Super NAT should be used to optimize address translation when the ISP assigns multiple public addresses to the site.

When Super NAT is enabled, the system automatically switches between PAT and NAT as follows:

￿	The OCR 812 utilizes NAT until all available public IP addresses have been
	￿used.
	When all public IP addresses have been used under NAT, the system
	switches to PAT in order to allow additional stations to access the Internet
	(“additional” meaning “beyond those allowed by the public ports”). PAT
	continues to run until a NAT port frees up.
	For more information, see Super Network Address Translation (Super NAT).
set vc <vc name> Use the set vc <vc name> nat_option command to set the NAT operating mode
nat_option for a vc profile.
Options available for the set vc <vc name> nat_option command are
as follows:
	NAT
	PAT
	Super_NAT
	Enable
￿	Disable
For a vc added using QuickVC, NAT is enabled by default.
Port Address Translation PAT uses the TCP and UDP port numbers to map multiple private port addressed
(PAT) LAN workstations (i.e. multiple users) to one public WAN port address.

Please note the following:

￿

￿

For normal applications such as Web browsing and FTP transfers, PAT can be configured by just enabling the feature. When accesses are originated from the LAN (which uses private addresses), a mapping is established between the (LAN) source port number and the (LAN) source private address. When the response is received on the public addressed WAN destination port, the destination port is mapped back to the (LAN) private address.

Static PAT port mappings (or the PAT default address) must be configured when an application will initiate a TCP or UDP connection from the public network. If a public accessible server resides on a privately addressed LAN, static ports can be defined for the applications they are running. For example, TCP port 80 (for a Web server) and TCP port 21 (for an FTP server) can be statically assigned. The PAT default address can be used with or instead of static port assignments, and is set to the private address of a workstation on the local LAN. If an incoming IP data packet is received on a WAN port and