ZyXEL Communications Prestige 2000W - Manual (Page 83)

Prestige 2000W_V2 User’s Guide
Chapter 12 User Web Configurator Screens 83
The following table summarizes how these NAT types handle outgoing and incoming packets.
Read the following sections for more details and examples.
The examples in these NAT type sections describe NAT translation between internal (private)
and external (public) IP addresses.
12.11.2.1 Full Cone NAT
In full cone NAT, the NAT router maps all outgoing packets from an internal IP address and
port to a single IP address and port on the external network. The NAT router also maps
packets coming to that external IP address and port to the internal IP address and port.
In the following example, the NAT router maps the source address of all packets sent from the
Prestige’s internal IP address 1 and port A to IP address 2 and port B on the external network.
The NAT router also performs NAT on all incoming packets sent to IP address 2 and port B
and sends them to IP address 1, port A.
Table 12
FULL CONE RESTRICTED CONE
PORT RESTRICTED
CONE
SYMMETRIC
Outgoing
Packets
The NAT router maps the internal IP address and port of all outgoing
packets to a single IP address and port on the external network.
The NAT router maps
the internal IP
address and port of
each outgoing packet
to a different external
IP address and port
for each different
destination IP
address and port.
Incoming
Packets
Any external host can
send packets to the
external IP address
and port.
Only external hosts
with an IP address to
which the internal
host has already sent
a packet can send
packets to the
external IP address
and port.
Only external hosts
with an IP address
and port to which the
internal host has
already sent a packet
can send packets to
the external IP
address and port.
A host on the
external network can
only send packets to
the specific external
IP address and port
that the NAT router
used in sending a
packet to the external
host’s IP address and
port.