Planet Technology 802.11g Wireless ADSL 2/2+ Router ADW-4401A/Bv2 - Manual (Page 46)

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Virtual Circuit (VC): The Virtual Circuit (VC) properties of the ATM VC interface
identify a unique path that your ADSL/Ethernet router uses to communicate via the
ATM-based network with the telephone company central office equipment.
NAT Status: This filed shows the current status of the NAT function for the current
VC.
Number of IPs: This field is to specify how many IPs are provided by your ISP for
current VC. It can be single IP or multiple IPs.
Note: For VCs with single IP, they share the same DMZ & Virtual servers; for VCs
with multiple IPs, each VC cab set DMZ and Virtual servers. Furthermore, for VCs
with multiple IPs, they can define the Address Mapping rules; for VCs with single IP,
since they have only one IP, there is no need to individually define the Address
Mapping rule.
What NAT Does
NAT changes the source IP address in a packet received from a subscriber (the inside
local address) to another (the inside global address) before forwarding the packet to the
WAN side. When the response comes back, NAT translates the destination address (the
inside global address) back to the inside local address before forwarding it to the
original inside host. Note that the IP address (either local or global) of an outside host is
never changed.
The global IP addresses for the inside hosts can be either static or dynamically assigned
by the ISP. You may also designate servers, such as a Web server and a telnet server, on
your local network and make them accessible to the outside world. With no servers
defined, your ROUTER filters out all incoming inquiries, thus preventing intruders