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Virtual Server
The DFL-80 VPN Firewall separates an enterprise's Intranet and Internet into
internal networks and external networks respectively. 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
using the Firewall's NAT (Network Address Translation) function. If a server
which provides service to the external networks, is located in the internal
networks, outside users can't directly connect to the server by using the server's
private IP address.
The DFL-80 Firewall's Virtual Server can solve this problem. A virtual server
has set the real IP address of the Firewall's external network interface to be
the Virtual Server IP. using the virtual server feature, the Firewall translates the
virtual server's IP address into a private IP address of the physical server in
the Internal (LAN) network. When outside users on the Internet request
connections to the virtual server, the request will be forwarded to the private
internal server.
Virtual Server includes another feature know as one-to-many mapping. This is
when one virtual server IP address on the external interface can be mapped
into 4 internal 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 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 is
opposite to NAT), but there still exists some differences:
!
Virtual Server can map one real IP to several internal physical servers
while Mapped IP can only map one real IP to one internal 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
internal 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 external
virtual server to the private internal IP address of the physical server that
supports the services. Therefore users from the external network can access
servers of the internal network by requesting the service from the IP address
provided by Virtual Server.
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