ZyXEL Communications P2000W manual Full Cone NAT, NAT Types

P-2000W_V2 User’s Guide

The following table summarizes how these NAT types handle outgoing and incoming packets. Read the following sections for more details and examples.

Table 12	NAT Types
	FULL CONE	RESTRICTED	PORT	SYMMETRIC
			RESTRICTED
		CONE
			CONE
Incoming	Any external host	Only external hosts	Only external hosts	A host on the external
Packets	can send packets to	with an IP address	with an IP address	network can only send
	the mapped	to which the internal	and port to which	packets to the specific
	external IP address	host has already	the internal host	mapped external IP
	and port.	sent a packet can	has already sent a	address and port that the
		send packets to the	packet can send	NAT router used in
		mapped external IP	packets to the	sending a packet to the
		address and port.	mapped external IP	external host’s IP address
			address and port.	and port.
Outgoing	The NAT router maps the internal IP address and port of all			The NAT router maps the
Packets	outgoing packets to a single IP address and port on the			internal IP address and
	external network.			port of each outgoing
				packet to a different
				external IP address and
				port for each different
				destination IP address
				and port.

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.

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