PLANET CS-1000 - Manual (Page 87)

Multi-Homing Security Gateway User’s Manual
Step 4: Configure Outgoing Policy rule to enable Content Blocking Function.
3.3.7 Virtual Server
The Multi-Homing Security Gateway separates an enterprise’s Intranet and Internet into LAN networks and
WAN networks respectively. Generally, 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
Multi-Homing Security Gateway’s NAT (Network Address Translation) function. If a server providing service to
the WAN networks is located in the LAN networks, outside users can’t directly connect to the server by using
the server’s private IP address.
The Multi-Homing Security Gateway’s Virtual Server can solve this problem. A virtual server has set the real
IP address of the Multi-Homing Security Gateway’s WAN network interface to be the Virtual Server IP.
Through the virtual server feature, the Multi-Homing Security Gateway translates the virtual server’s IP
address into the private IP address of physical server in the LAN network. When outside users on the Internet
request connections to the virtual server, the request will be forwarded to the private LAN server.
Virtual Server owns another feature known as one-to-many mapping. This is when one virtual server IP
address on the WAN interface can be mapped into 4 LAN network server 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 sending all data packets to all similar servers, this increases the
server’s efficiency, reduces risks of server crashes, and enhances servers’ stability.
How to use Virtual Server and mapped IP
Virtual Server and Mapped IP are part of the IP mapping (also called DMZ, De-Militarization Zone) scheme.
By applying the incoming policies, Virtual Server and IP mapping work similarly. They map real IP addresses
to the physical servers’ private IP addresses (which are opposite to NAT), but there are still some differences:
„ Virtual Server can map one real IP to several LAN physical servers while Mapped IP can
only map one real IP to one LAN physical server (1-to-1 Mapping). The Virtual Servers’ load
balance feature can map a specific service request to different physical servers running the
same services.
„ Virtual Server can only map one real IP to one service/port of the LAN physical servers
while Mapped IP maps one real IP to all the services offered by the physical server.
„ IP mapping and Virtual Server work by binding the IP address of the WAN virtual server to
the private LAN IP address of the physical server that supports the services. Therefore
users from the WAN network can access servers of the LAN network by requesting the
service from the IP address provided by Virtual Server.
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