P-2302R Series User’s Guide

Figure 31 NAT: Incoming

7.3.2 NAT Types

This section discusses the following NAT types that may be implemented on a router in front of the Prestige.

•Full Cone

•Restricted Cone

•Port Restricted Cone

•Symmetric

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

Table 20

NAT Types

 

 

 

 

 

 

 

 

 

 

 

 

RESTRICTED

PORT

 

 

 

FULL CONE

RESTRICTED

SYMMETRIC

 

 

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.

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Chapter 7 Introduction to VoIP