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Table Of Contents
Configuring H.323 Support for Virtual Interfaces
Supported Standards, MIBs, and RFCs
Verifying the Gateway's Source IP Address
Configuring H.323 Support for Virtual Interfaces
Document Update Alert
This document was originally produced for Cisco IOS Release 12.1(2)T. This feature has been updated in subsequent releases, and more recent documentation is available.
If you are using Cisco IOS Release 12.3 or higher, refer to the following sections in the Cisco IOS H.323 Configuration Guide of the Cisco IOS Voice Configuration Library, Release 12.3:
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Configuring H.323 Support for Virtual Interfaces
If you are using Cisco IOS Release 12.2 or higher, refer to the following sections in the Configuring H.323 Gateways chapter of the Cisco IOS Voice, Video, and Fax Configuration Guide, Release 12.2:
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This document describes the H.323 Support for Virtual Interfaces that was introduced in Cisco IOS Release 12.1(2)T. This document contains the following sections:
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Feature Overview
The H.323 Support for Virtual Interfaces feature allows users to configure the IP address of the gateway, so that the IP address included in the H.323 packet is deterministic and consistently indicates the same address for the source.
Benefits
In previous releases of the Cisco IOS software, the source address included in the H.323 packet could vary depending on the protocol (RAS, H.225, H.245, or RTP). This makes it difficult to configure firewall applications to work with H.323 messages.
The H.323 Support for Virtual Interfaces feature addresses that difficulty by allowing the user to explicitly configure an IP address to be used for all protocols.
Restrictions
The H.323 Support for Virtual Interfaces feature has no restrictions or limitations.
Related Documents
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Supported Platforms
The H.323 Support for Virtual Interfaces feature is supported on any existing IOS voice platforms, including the following:
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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.
For descriptions of supported MIBs and how to use MIBs, see the Cisco MIB web site on CCO.
RFCs
No new or modified RFCs are supported by this feature.
Prerequisites
The H.323 Support for Virtual Interfaces feature requires the Cisco H.323 VoIP Gateway for Cisco Access Platforms feature.
Configuration Tasks
To use the H.323 Support for Virtual Interfaces feature, first ensure that the VoIP gateway functionality is enabled. For more information about enabling the VoIP gateway functionality, see
Configuring Voice over IP. To configure a source IP address for the gateway, do the following:
Verifying the Gateway's Source IP Address
To verify the gateway's source IP address, enter the show run command. The output shows the source IP address that is bound to the interface.
router# show runBuilding configuration...Current configuration:!...interface Loopback0ip address 1.1.1.1 255.255.255.0no ip directed-broadcasth323-gateway voip bind srcaddr 1.1.1.1!interface Ethernet0/0ip address 172.18.194.50 255.255.255.0no ip directed-broadcasth323-gateway voip interfaceh323-gateway voip id j70f_2600_gk2 ipaddr 172.18.194.53 1719h323-gateway voip h323-id j70f_3640_gw1h323-gateway voip tech-prefix 3#...Configuration Examples
In the following example, the Ethernet 0/0 interface is used as the gateway interface. For convenience, we have also specified the h323-gateway voip bind srcaddr command on the same interface. The designated source IP address is the same as the IP address assigned to the interface.
interface Ethernet0/0ip address 172.18.194.50 255.255.255.0no ip directed-broadcasth323-gateway voip interfaceh323-gateway voip id j70f_2600_gk2 ipaddr 172.18.194.53 1719h323-gateway voip h323-id j70f_3640_gw1h323-gateway voip tech-prefix 3#h323-gateway voip bind srcaddr 172.18.194.50Command Reference
This section documents new or modified commands. All other commands used with this feature are documented in the Cisco IOS Release 12.1 command reference publications.
h323-gateway voip srcaddr
To designate a source IP address for the voice gateway, use the h323-gateway voip bind srcaddr command. To remove the source IP address, use the no form of the command.
h323-gateway voip bind srcaddr ip_address
no h323-gateway voip bind srcaddr
Syntax Description
Defaults
There are no default behaviors or values for this command.
Command Modes
Interface configuration
Command History
Usage Guidelines
You do not have to issue this command on the interface that you defined as the voice gateway interface (although it may be more convenient to do so). Use this command the interface that contains the IP address to which you want to bind.
Examples
The following example assigns a source IP address of 1.1.1.1:
h323-gateway voip bind srcaddr 1.1.1.1Related Commands
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Glossary
gatekeeper—A gatekeeper maintains a registry of devices in the multimedia network. The devices register with the gatekeeper at startup, and request admission to a call from the gatekeeper.
The gatekeeper is an H.323 entity on the LAN that provides address translation and control access to the LAN for H.323 terminals and gateways. The gatekeeper may provide other services to the H.323 terminals and gateways, such as bandwidth management and locating gateways.
gateway—A gateway allows H.323 terminals to communicate with non-H.323 terminals by converting protocols. A gateway is the point at which a circuit-switched call is encoded and repackaged into IP packets.
A H.323 gateway is an endpoint on the LAN that provides real-time, two-way communications between H.323 terminals on the LAN and other ITU-T terminals in the WAN, or to another H.323 gateway.
H.323—An International Telecommunication Union (ITU-T) standard that describes packet-based video, audio, and data conferencing. H.323 is an umbrella standard that describes the architecture of the conferencing system, and refers to a set of other standards (H.245, H.225.0, and Q.931) to describe its actual protocol.
RAS—Registration, admission, and status protocol. This is the protocol that is used between endpoints and the gatekeeper to perform management functions. The RAS signaling function performs registration, admissions, bandwidth changes, status, and disengage procedures between the VoIP gateway and the gatekeeper.
RTP—Real-time transport protocol. One of the IPv6 protocols. RTP is designed to provide end-to-end network transport functions for applications transmitting real-time data, such as audio, video, or simulation data, over multicast or unicast network services. RTP provides services such as payload type identification, sequence numbering, timestamping, and delivery monitoring to real-time applications.
VoIP—Voice over IP. The ability to carry normal telephone-style voice over an IP-based Internet with POTS-like functionality, reliability, and voice quality. VoIP is a blanket term which generally refers to Cisco's standards-based (H.323, etc.) approach to IP voice traffic.