Appendix F NAT
P-2304R-P1 Series User’s Guide
264
Restricted Cone NAT
As in full cone NAT, a 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 NAT is in how the restricted cone NAT router handles packets
coming in from the external network. A host on the external network (IP address
3
or IP
address
4
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.
A ZyXEL Device with IP address
1
and port
A
sends packets to IP address
3
and IP address
4
.
The NAT router changes the ZyXEL Device’s IP address to
2
and port to
B
.
Both
4, D
and
4, E
can send packets to
2
,
B
since
1
,
A
has already sent packets to
4
. The NAT
router will perform NAT on the packets from
4, D
and
4, E
and send them to the ZyXEL
Device at IP address
1
, port
A
. Packets have not been sent from
1
,
A
to
3
or
5
, so
3
and
5
cannot send packets to
1
,
A
.
Figure 156
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
.
Содержание P-2304R
Страница 1: ...www zyxel com P 2304R P1 Series VoIP Station Gateway User s Guide Version 3 60 10 2006 Edition 1...
Страница 2: ......
Страница 8: ...Contents Overview P 2304R P1 Series User s Guide 8...
Страница 26: ...26...
Страница 32: ...Chapter 1 Introducing the ZyXEL Device P 2304R P1 Series User s Guide 32...
Страница 40: ...Chapter 2 Introducing the Web Configurator P 2304R P1 Series User s Guide 40...
Страница 73: ...73 PART II Network WAN 75 LAN 85 NAT 97...
Страница 74: ...74...
Страница 105: ...105 PART III VoIP SIP 107 Phone 121 Phone Book 129...
Страница 106: ...106...
Страница 116: ...Chapter 9 SIP P 2304R P1 Series User s Guide 116 Figure 60 VoIP SIP SIP Settings Advanced...
Страница 128: ...Chapter 10 Phone P 2304R P1 Series User s Guide 128...
Страница 134: ...Chapter 11 Phone Book P 2304R P1 Series User s Guide 134...
Страница 135: ...135 PART IV Security and Management Firewall 137 Content Filter 145 Static Route 149 Bandwidth MGMT 153 Remote MGMT 165...
Страница 136: ...136...
Страница 144: ...Chapter 12 Firewall P 2304R P1 Series User s Guide 144...
Страница 148: ...Chapter 13 Content Filter P 2304R P1 Series User s Guide 148...
Страница 152: ...Chapter 14 Static Route P 2304R P1 Series User s Guide 152...
Страница 173: ...173 PART V Maintenance and Troubleshooting UPnP 175 System 187 Logs 195 Tools 209 Troubleshooting 215...
Страница 174: ...174...
Страница 186: ...Chapter 17 UPnP P 2304R P1 Series User s Guide 186...
Страница 194: ...Chapter 18 System P 2304R P1 Series User s Guide 194...
Страница 208: ...Chapter 19 Logs P 2304R P1 Series User s Guide 208...
Страница 220: ...Chapter 21 Troubleshooting P 2304R P1 Series User s Guide 220...
Страница 222: ...222...
Страница 228: ...Appendix A Product Specifications P 2304R P1 Series User s Guide 228...
Страница 258: ...Appendix E SIP Passthrough P 2304R P1 Series User s Guide 258...
Страница 290: ...Appendix I Legal Information P 2304R P1 Series User s Guide 290...
