Table Of Contents
NAT—Enhanced H.225/H.245 Forwarding Engine
Supported Standards, MIBs, and RFCs
NAT—Enhanced H.225/H.245 Forwarding Engine
This feature module describes the enhanced Cisco IOS Network Address Translation (NAT) support of H.225/H.245 forwarding engine and includes the following sections:
•
Supported Standards, MIBs, and RFCs
Feature Overview
During the call setup between H.323 terminals, the following protocols are used:
•
•
Both protocol messages contain embedded IP addresses and ports. Any message passing through a router running NAT must be decoded, translated, and encoded back to the packet.
Previously, there was minimal support in NAT for certain H.225/H.245 messages that are used by Microsoft NetMeeting.
Note
Benefits
This enhancement provides support for all H.225/H.245 protocol messages and embedded addresses.
Related Documents
•
•
Supported Platforms
•
•
•
•
•
•
•
•
Supported Standards, MIBs, and RFCs
Standards
No new or modified standards are supported by this feature.
MIBs
No new or modified MIBs are supported by this feature.
To obtain lists of supported MIBs and how to use MIBs, see the Cisco MIB web site on CCO at http://www.cisco.com/public/sw-center/netmgmt/cmtk/mibs.shtml.
RFCs
No new or modified RFCs are supported by this feature.
Configuration Tasks
None
Configuration Examples
None
Debug Commands
This section documents the modified debug ip nat command. All other commands used with this feature are documented in the Cisco IOS Release 12.1 command reference publications.
debug ip nat
To display information about IP packets translated by the IP Network Address Translation (NAT) feature, use the debug ip nat privileged EXEC command. To disable debugging output, use the no form of this command.
debug ip nat [access-list | detailed | h323 | pptp]
no debug ip nat [access-list | detailed | h323 | pptp]
Syntax Description
Defaults
Disabled
Command Modes
Global configuration
Command History
11.2
This command was introduced.
12.1(5)T
This command was modified to include h323 keyword.
Usage Guidelines
The NAT feature reduces the need for unique, registered IP addresses. It can also save private network administrators from needing to renumber hosts and routers that do not conform to global IP addressing.
Use the debug ip nat command to verify the operation of the NAT feature by displaying information about every packet that is translated by the router. The debug ip nat detailed command generates a description of each packet considered for translation. This command also outputs information about certain errors or exceptional conditions, such as the failure to allocate a global address. To display messages related to the processing of H.225 signalling and H.245 messages, use the debug ip nat h323 command.
Caution
Examples
The following is sample output from the debug ip nat command. In this example, the first two lines show the debugging output produced by a Domain Name System (DNS) request and reply. The remaining lines show the debugging output from a Telnet connection from a host on the inside of the network to a host on the outside of the network. All Telnet packets, except for the first packet, were translated in the fast path, as indicated by the asterisk (*).
Router# debug ip natNAT: s=192.168.1.95->172.31.233.209, d=172.31.2.132 [6825]NAT: s=172.31.2.132, d=172.31.233.209->192.168.1.95 [21852]NAT: s=192.168.1.95->172.31.233.209, d=172.31.1.161 [6826]NAT*: s=172.31.1.161, d=172.31.233.209->192.168.1.95 [23311]NAT*: s=192.168.1.95->172.31.233.209, d=172.31.1.161 [6827]NAT*: s=192.168.1.95->172.31.233.209, d=172.31.1.161 [6828]NAT*: s=172.31.1.161, d=172.31.233.209->192.168.1.95 [23313]NAT*: s=172.31.1.161, d=172.31.233.209->192.168.1.95 [23325]Table 1 describes the significant fields shown in the display.
The following is sample output from the debug ip nat detailed command. In this example, the first two lines show the debugging output produced by a DNS request and reply. The remaining lines show the debugging output from a Telnet connection from a host on the inside of the network to a host on the outside of the network. In this example, the inside host 192.168.1.95 was assigned the global address 172.31.233.193.
Router# debug ip nat detailedNAT: i: udp (192.168.1.95, 1493) -> (172.31.2.132, 53) [22399]NAT: o: udp (172.31.2.132, 53) -> (172.31.233.193, 1493) [63671]NAT*: i: tcp (192.168.1.95, 1135) -> (172.31.2.75, 23) [22400]NAT*: o: tcp (172.31.2.75, 23) -> (172.31.233.193, 1135) [22002]NAT*: i: tcp (192.168.1.95, 1135) -> (172.31.2.75, 23) [22401]NAT*: i: tcp (192.168.1.95, 1135) -> (172.31.2.75, 23) [22402]NAT*: o: tcp (172.31.2.75, 23) -> (172.31.233.193, 1135) [22060]NAT*: o: tcp (172.31.2.75, 23) -> (172.31.233.193, 1135) [22071]Table 2 describes the significant fields shown in the display.
The following is sample output from the debug ip nat h323 command. In this example, an H.323 call is established between two hosts, one host on the inside and the other one on the outside. The debug displays the H.323 messages names that NAT recognizes and the embedded IP addresses contained in those messages.
Router# debug ip nat h323NAT:H225:[0] processing a Setup messageNAT:H225:[0] found Setup sourceCallSignallingNAT:H225:[0] fix TransportAddress addr=192.168.122.50 port=11140NAT:H225:[0] found Setup fastStartNAT:H225:[0] Setup fastStart PDU length:18NAT:H245:[0] processing OpenLogicalChannel message, forward channelnumber 1NAT:H245:[0] found OLC forward mediaControlChannelNAT:H245:[0] fix TransportAddress addr=192.168.122.50 port=16517NAT:H225:[0] Setup fastStart PDU length:29NAT:H245:[0] processing OpenLogicalChannel message, forward channelnumber 1NAT:H245:[0] found OLC reverse mediaChannelNAT:H245:[0] fix TransportAddress addr=192.168.122.50 port=16516NAT:H245:[0] found OLC reverse mediaControlChannelNAT:H245:[0] fix TransportAddress addr=192.168.122.50 port=16517NAT:H225:[1] processing an Alerting messageNAT:H225:[1] found Alerting fastStartNAT:H225:[1] Alerting fastStart PDU length:25NAT:H245:[1] processing OpenLogicalChannel message, forward channeTable 3 describes the significant fields shown in the display.
Guest
