PLANET SG-500 - Manual (Page 109)

SG-500 VPN Security Gateway User’s Manual
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4.17 Virtual Server
The real IP address provided from ISP is always not enough for all the users when the system
manager applies the network connection from ISP. Generally speaking, in order to allocate enough
IP addresses for all computers, an enterprise assigns each computer a private IP address, and
converts it into a real IP address through SG-500’s NAT (Network Address Translation) function.
If a server that provides service to WAN network is located in LAN networks, external users cannot
directly connect to the server by using the server’s private IP address.
The SG-500’s Virtual Server function can solve this problem. A Virtual Server has set the real IP
address of the SG-500’s WAN network interface to be the Virtual Server IP. Through the Virtual
Server function, the SG-500 translates the Virtual Server’s IP address into the private IP address in
the LAN network.
Virtual Server owns another feature know as one-to-many mapping. This is when one real server IP
address on the WAN interface can be mapped into four LAN network servers provide the same
service private IP addresses. This option is useful for Load Balancing, which causes the Virtual
Server to distribute data packets to each private IP addresses (which are the real servers) by session.
Therefore, it can reduce the loading of a single server and lower the crash risk. And can improve the
work efficiency.