P-2302R-P1 Series User’s Guide
266
Appendix E NAT
Figure 144
Restricted Cone NAT Example
Port Restricted Cone NAT
As in full cone NAT, a port restricted cone NAT router maps all outgoing packets from an
internal IP address and port to a single IP address and port on the external network. In the
following example, the NAT router maps the source address of all packets sent from internal
IP address
1
and port
A
to IP address
2
and port
B
on the external network.
The difference from full cone and restricted cone NAT is in how the port restricted cone NAT
router handles packets coming in from the external network. A host on the external network
(IP address
3
and Port
C
for example) can only send packets to the internal host if the internal
host has already sent a packet to the external host’s IP address and port.
A ZyXEL Device with IP address
1
and port
A
sends packets to IP address
3
, port
C
and IP
address
4
, port
D
. The NAT router changes the ZyXEL Device’s IP address to
2
and port to
B
.
Since
1
,
A
has already sent packets to
3
,
C
and
4
,
D,
they can send packets back to
2
,
B
and the
NAT router will perform NAT on them and send them to the ZyXEL Device at IP address
1
,
port
A
.
Packets have not been sent from
1
,
A
to
4
,
E
or
5
, so they cannot send packets to
1
,
A
.
Summary of Contents for P-2302R-P1 Series
Page 1: ...P 2302R P1 Series VoIP ATA Station Gateway User s Guide Version 3 60 Edition 1 5 2006...
Page 2: ......
Page 5: ...P 2302R P1 Series User s Guide Certifications 5...
Page 10: ...P 2302R P1 Series User s Guide 10 Customer Support...
Page 38: ...P 2302R P1 Series User s Guide 38 Chapter 1 Introducing the ZyXEL Device...
Page 46: ...P 2302R P1 Series User s Guide 46 Chapter 2 Introducing the Web Configurator...
Page 106: ...P 2302R P1 Series User s Guide 106 Chapter 7 LAN...
Page 125: ...P 2302R P1 Series User s Guide Chapter 9 SIP 125 Figure 60 VoIP SIP SIP Settings Advanced...
Page 130: ...P 2302R P1 Series User s Guide 130 Chapter 9 SIP...
Page 140: ...P 2302R P1 Series User s Guide 140 Chapter 10 Phone...
Page 146: ...P 2302R P1 Series User s Guide 146 Chapter 11 Phone Book...
Page 160: ...P 2302R P1 Series User s Guide 160 Chapter 14 Content Filter...
Page 174: ...P 2302R P1 Series User s Guide 174 Chapter 15 Bandwidth MGMT...
Page 184: ...P 2302R P1 Series User s Guide 184 Chapter 17 Static Route...
Page 208: ...P 2302R P1 Series User s Guide 208 Chapter 19 System...
Page 224: ...P 2302R P1 Series User s Guide 224 Chapter 20 Logs...
Page 234: ...P 2302R P1 Series User s Guide 234 Appendix A Product Specifications...
Page 256: ...P 2302R P1 Series User s Guide 256 Appendix C IP Subnetting...
Page 258: ...P 2302R P1 Series User s Guide 258 Appendix D SIP Passthrough...
Page 288: ...P 2302R P1 Series User s Guide 288 Appendix G Services...
