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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:
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.
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.
The H.323 Support for Virtual Interfaces feature has no restrictions or limitations.
The H.323 Support for Virtual Interfaces feature is supported on any existing IOS voice platforms, including the following:
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.
The H.323 Support for Virtual Interfaces feature requires the Cisco H.323 VoIP Gateway for Cisco Access Platforms feature.
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 H.323 VoIP Gateway for Cisco Access Platforms. To configure a source IP address for the gateway, do the following:
| Command | Purpose | |
|---|---|---|
Step 1 | Router# config term | Enters global configuration mode. |
Step 2 | Router(config)# interface type slot/port | Enters interface configuration mode to configure parameters for the specified interface. The type attribute indicates the type of interface. The slot/port attribute indicates the location of the interface in the router. |
Step 3 | Router(config-if)# h323-gateway voip bind srcaddr ip_address | Sets the source IP address to be used for this gateway. The ip_address attribute indicates the address to be used as the source IP address for the gateway. |
 |
Note You can issue the h323-gateway voip bind srcaddr command on any interface in the router. Issuing the command for one interface assigns the source address for the entire router. |
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 run Building configuration... Current configuration: ! . . . interface Loopback0 ip address 1.1.1.1 255.255.255.0 no ip directed-broadcast h323-gateway voip bind srcaddr 1.1.1.1 ! interface Ethernet0/0 ip address 172.18.194.50 255.255.255.0 no ip directed-broadcast h323-gateway voip interface h323-gateway voip id j70f_2600_gk2 ipaddr 172.18.194.53 1719 h323-gateway voip h323-id j70f_3640_gw1 h323-gateway voip tech-prefix 3# . . .
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 Ethernet0/0 ip address 172.18.194.50 255.255.255.0 no ip directed-broadcast h323-gateway voip interface h323-gateway voip id j70f_2600_gk2 ipaddr 172.18.194.53 1719 h323-gateway voip h323-id j70f_3640_gw1 h323-gateway voip tech-prefix 3# h323-gateway voip bind srcaddr 172.18.194.50
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.
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
Syntax Description
ip_address Specify the source IP address in dotted-decimal notation.
Defaults
There are no default behaviors or values for this command.
Command Modes
Interface configuration
Command History
12.1(2)T This command was introduced.
Release
Modification
Usage Guidelines
You can issue this command on any interface in the router. You do not have to issue it on the interface that you defined as the voice gateway interface (although it may be more convenient to do so). Issuing the command for one interface assigns the source IP address for the entire router.
Examples
The following example assigns a source IP address of 1.1.1.1:
h323-gateway voip bind srcaddr 1.1.1.1
Related Commands
None
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.
Posted: Thu Sep 14 18:34:21 PDT 2000
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