Table of Contents

Feature Overview

H.323v2 Fast Connect
H.245 Tunneling
H.450.2 Call Transfer
H.450.3 Call Deflection
Hookflash Relay
H.235 Security
GKTMP
Gateway Support for Alternate Endpoints
Gateway Support for a Network-Based Billing Number
Gateway Support for Voice-Port Description

Benefits
Restrictions

Related Features and Technologies
Related Documents

Supported Platforms
Supported Standard MIBs and RFCs
Prerequisites
Configuration Tasks

Configuring H.323 Fast Connect
Configuring H.245 Tunneling
Configuring H.450

Configuring Call Deflection
Configuring Call Transfer Without Consultation
Configuring Voice-Port Descriptions

Configuring a RADIUS/AAA Server
Configuring the Gatekeeper

Configuring a Dialing Prefix for each Gateway
Configuring a Gatekeeper for Interaction with External Applications
Configuring Triggers for External Applications

Configuration Examples
Command Reference
security token required-for
server registration-port
server trigger
timing hookflash-input
timing hookflash-output
show Gatekeeper servers
debug Gatekeeper server
Glossary

Cisco H.323 Version 2 Phase 2

This feature module describes enhancements to Cisco H.323 Version 2 for Phase 2, which is described in the following sections:

• Feature Overview

• Supported Platforms

• Supported Standard MIBs and RFCs

• Prerequisites

• Configuration Examples

• Command Reference

• Glossary

Feature Overview

Cisco H.323 Version 2 Phase 2 upgrades Cisco IOS software by adding several optional features of the H.323 Version 2 specification and facilitates customized extensions to the Cisco Gatekeeper.

H.323v2 Fast Connect

The Fast Connect feature allows endpoints to establish media channels without waiting for a separate H.245 connection to be opened. This streamlines the number of messages that are exchanged and the amount of processing that must be done before endpoint connections can be established. A high-level view of the Fast Connect procedures within the H.323 protocol follows:

1. The calling endpoint transmits a SETUP message containing the fastStart element that contains a sequence of encoded logical channel structures, each representing a different capability media type for both "send" and "receive" directions.

2. The called endpoint selects one or more of the media types offered by the calling endpoint for the send and receive directions and returns its selections as logically encoded Q.931 messages up to and including CONNECT. At this point, the called endpoint must be prepared to receive media along any of the channels it selected.

3. If H.245 procedures are needed and one or both of the endpoints do not support tunneling, then a separate H.245 connection is used.

This feature is not explicitly configurable. It is assumed that the gateway is capable of sending and receiving Fast Connect procedures unless its corresponding dial peer has been configured for RSVP (in other words, the req-qos is set to a value other than the default of best-effort). If the dial peer has been configured for RSVP, then traditional "slow" connect procedures will be followed, and the endpoint will neither attempt to initiate Fast Connect nor respond to a Fast Connect request from its peer.

A terminating endpoint can reject Fast Connect by simply omitting the fastStart element from all Q.931 messages up to and including CONNECT. In this case, normal H.245 procedures are followed and a separate H.245 TCP connection is established. So, if an endpoint does not support the Fast Connect procedures, normal H.245 procedures are followed. In addition, certain conditions can cause a Fast Connect call to fall back to normal H.245 procedures to complete the call.

Once a media connection has been opened (an audio path has been established), either endpoint has the option of switching to H.245 procedures (if they are needed) by using H.245 tunneling, whereby H.245 messages are encapsulated within the h245Control element of Q.931 messages.

The dtmf-relay command is the only H.245 cognizant command that can initiate H.245 tunneling procedures from a Fast Connect call. If H.245 tunneling is active on the call, switching to a separate TCP H.245 connection is not supported.

A Cisco terminating endpoint accepts a Fast Connect request only if a pair of symmetric codecs (codecs in both directions are the equivalent or identical) can be selected from a list that has been offered. The originating endpoint is constrained only by what it can send through the codec (or voice class codec list) associated with the dial peer.

If the Cisco originating endpoint has offered multiple codecs and the terminating endpoint selects a pair of asymmetric (mismatched) codecs, then, the originating endpoint initiates separate H.245 procedures to correct the asymmetric codec situation.

Fast Connect is backward compatible with H.323 Version 1 configurations.

H.245 Tunneling

Through H.245 tunneling, H.245 messages are encapsulated within Q.931 messages without using a separate H.245 TCP connection. When tunneling is enabled, one or more H.245 messages can be encapsulated in any Q.931 message. H.245 tunneling is not supported as a standalone feature; initiation of H.245 tunneling procedures can be initiated only by using the dtmf-relay command, and only from an active Fast Connect call. Furthermore, if dtmf-relay is configured on a Version 2 VoIP dial peer and the active call has been established by using Fast Connect, tunneling procedures initiated by the opposite endpoint are accepted and supported.

H.245 tunneling is backward compatible with H.323 Version 1 configurations.

H.450.2 Call Transfer

Call Transfer allows an H.323 endpoint to redirect an answered call to another H.323 endpoint. Cisco gateways support H.450.2 Call Transfer as the transferred and transferred-to party. The transferring endpoint must be an H.450-capable terminal; the Cisco gateway cannot act as the transferring endpoint. Gatekeeper-controlled or Gatekeeper-initiated Call Transfer is not supported.

Note Certain devices are limited in their support of H.450. The Cisco 1700 and ubr820 platforms do not support Interactive Voice Response (IVR). Therefore, these platforms are not able to act as H.450 Transferring endpoints.

H.450.2 specifies two variants of Call Transfer:

1. Transfer without consultation---The transferring endpoint supplies the number of the transferred-to endpoint as part of the transfer request, and the two remote endpoints are transferred together. As mentioned above, a Cisco gateway cannot be the transferring endpoint.

2. Transfer with consultation---This feature is not currently supported.

H.450.3 Call Deflection

Call Deflection is a feature under H.450.3 Call Diversion (Call Forwarding) that allows a called H.323 endpoint to redirect the unanswered call to another H.323 endpoint. Cisco gateways support H.450.3 Call Deflection as the originating, deflecting, and deflected-to gateway. The Cisco gateway as the deflecting gateway will support invocation of Call Deflection only by using an incoming PRI QSIG message (a Call Deflection cannot be invoked by using any other trunk type).

If the deflecting endpoint is a Cisco gateway, the telephony endpoint on the deflecting gateway's PRI invokes Call Deflection by sending an equivalent QSIG Reroute Invoke within a FACILITY message to the gateway. The deflecting gateway then uses the procedures outlined in H.450.3 Call Deflection to transfer the call to another endpoint. Note that the initiation of Deflection using QSIG Reroute Invoke is valid only on calls that arrived as H.323 calls at the deflecting Gateway. In other words, for calls that arrived at the Gateway through a telephony interface (such as a hairpin call) or using a non-H.323 IP protocol, QSIG Reroute Invoke will be ignored.

H.323 Version 2 Phase 2 does not support Gatekeeper-controlled or initiated Call Deflection.

Note Certain devices are limited in their support of H.450. The Cisco 5800 is not able to convert QSIG to H.450. The Cisco 1700 and ubr820 platforms do not support IVR. Therefore, these devices are not able to act as H.450 Deflecting endpoints.

Hookflash Relay

A "hookflash" indication is a brief on-hook condition during a call. The indication is not long enough in duration to be interpreted as a signal to disconnect the call. You can create a hookflash indication by quickly depressing and releasing the hook on your telephone.

PBXs and telephone switches are frequently programmed to intercept hookflash indications and use them as a way to allow a user to invoke supplemental services. For example, your local service provider might allow you to enter a hookflash as a means of switching between calls if you subscribe to a call-waiting service.

In the traditional telephone network, a hookflash results in a voltage change on the telephone line. Because there is no equivalent of this voltage change in an IP network, the ITU H.245 standard defines a message representing a hookflash. To send a hookflash indication using this message, an H.323 endpoint sends an H.245 user input indication message containing a "H.245-signal" or "H.245-alpha" structure with a value of "!". This value represents a hookflash indication.

Figure 1: Translating an FXS hookflash to an H.245 User Input

In H.323 Version 2 Phase 2, an FXS hookflash relay is generated only if the following two conditions are met:

1. The other endpoint must support the reception of an H.245 hookflash and advertise this using the "Receive User Input Capability" message during H.245 capabilities exchange;

2. The call must be established with either the "H245-alpha" or "h245-signal" variant of dtmf-relay.

This implies that the VoIP dial peer must be configured for dtmf-relay h245-alpha or h245-signal, but not cisco-rtp.

Enter the timing hookflash-input command on FXS interfaces to specify the maximum length in milliseconds of a hookflash indication. If the hookflash lasts longer than the specified limit, then the FXS interface processes the indication as an onhook.

The acceptable duration of a hookflash indication varies by equipment vendor and by country. One PBX can consider a 250 ms on-hook condition to be a hookflash; another PBX can consider this condition to be a disconnect.

H.235 Security

Security for Registration, Admission, and Status protocol (RAS) signaling between H.323 endpoints and Gatekeepers is enhanced in H.323 Version 2 Phase 2 by including secure endpoint registration of the Cisco gateway to the Cisco Gatekeeper and secure per-call authentication. The authentication type is "password with hashing" as described in ITU H.235. Specifically, the encryption method is MD5 with password hashing. This functionality is provided by the security token required-for CLI on the Gatekeeper and the security password CLI on the gateway.

The Gatekeeper can interact with a RADIUS security server to perform the authentications. The gateway can also authenticate an external application by using the Gatekeeper Transaction Message Protocol (GKTMP) API.

Per-call authentication is accomplished by validating account and pin numbers that are entered by the user connected to the calling gateway by using an interactive voice response (IVR) prompt.

The security mechanisms described above require the gateway and Gatekeeper clocks to be synchronized within 30 seconds of each other by using a Network Time Protocol (NTP) server.

GKTMP

The Gatekeeper Transaction Message Protocol (GKTMP) for the Cisco Gatekeeper provides a transaction-oriented application protocol that allows an external application to modify Gatekeeper behavior by processing specified RAS messages.

You can specify a set of triggers that use RAS messages that the Gatekeeper recognizes. Triggers are specified filter conditions that must match each type of RAS message. These triggers can be dynamically registered by using the external application, or you can configure this information by using the CLI on the Gatekeeper.

When the Gatekeeper receives a RAS message that meets the specified trigger conditions, it forwards the message to the external application in a GKTMP message format. This message is text encoded and sent over TCP. The external application can then modify fields in the message before returning it to the Gatekeeper for further processing, or it may return a RAS response to the Gatekeeper to be forwarded to the RAS client.

The following messages can be sent in GKTMP:

• ACF---Admission Confirm

• ARJ---Admission Reject

• ARQ---Admission Request

• LCF---Location Confirm

• LRJ---Location Reject

• LRQ---Location Request

• RCF---Registration Confirm

• RRQ---Registration Request

• RRJ---Registration Reject

• URQ---Unregistration Request

The application server interprets RAS messages in the following ways:

• For RRQ, URQ, the application server performs Gatekeeper authorization, storing endpoint RAS Gatekeeper IP addresses, and maintaining Gatekeeper resource control.

• For ARQ, LRQ, the application server performs authorization and digit translation functions and returns terminating IP addresses or a new E.164 address to the Gatekeeper for reorigination by the originating gateway.

• For LCF, LRJ the application server intercepts location responses from a distant Gatekeeper and modifies the message fields before responding to the originating gateway.

Note Cisco has developed an API that you can use to provide an interface to the Cisco Gatekeeper. See the Cisco Gatekeeper External Interface Reference.

To configure the Gatekeeper to receive trigger registrations from the external applications, specify the server's registration port using the server registration-port command where the Gatekeeper listens for server connections.

You can also configure the Gatekeeper to initiate the connection to a specified external application by using the server trigger command to specify a set of static trigger conditions for a specified server. You can specify only one application server for each server trigger command. All RAS messages that don't match the selection criteria for any external application are processed normally by the Gatekeeper. You can enter the show Gatekeeper servers and debug Gatekeeper servers commands to assist in the configuration.

Gateway Support for Alternate Endpoints

The Alternate Endpoint feature allows a Gatekeeper to specify alternative destinations for a call when queried with an Admission Request (ARQ) by an originating gateway. If the first destination gateway fails to connect, the Gatekeeper tries all the alternate destinations before going to the next dial peer rotary (if a rotary is configured).

Note This feature is not supported by the Cisco Gatekeeper; it is intended for use with third-party Gatekeepers that implement the Alternate Endpoint field in the ACF message. No support is provided for the gateway to send a list of alternate endpoints in RRQ messages.

Gateway Support for a Network-Based Billing Number

This feature informs the Gatekeeper of the specific voice port or T1/E1 span from which an incoming call entered the ingress gateway. This is done using a Cisco proprietary, nonstandard field that has been added to the Admission Request (ARQ) message sent by the ingress gateway. No configuration is necessary for this feature.

Gateway Support for Voice-Port Description

This feature provides the Gatekeeper with a configurable string that identifies the voice port or T1/E1 span from which an incoming call entered the ingress gateway. This is done using a Cisco proprietary, nonstandard field that has been added to the ARQ message sent by the ingress gateway. The string in the ARQ corresponds to the setting of the voice-port description command.

This feature is similar to network-based billing number feature, but differs in two important respects:

• The voice-port description field is only included in the ARQ if the voice-port description is configured through the CLI for the applicable voice-port.

• Because the voice-port description is configurable, the user can provide customer-specific information to the Gatekeeper. For example, the voice-port description can be configured to correspond to the Carrier Identification Code (CIC) for calls received on a particular T1/E1 Span.

Benefits

Cisco H.323 Version 2 Phase 2 adds the following benefits to Cisco H.323 Gatekeepers, gateways, and proxies:

• H.323v2 Fast Connect allows endpoints to establish media channels for audio exchange without waiting for a separate H.245 connection to be opened.

• H.245 tunneling allows H.245 messages to be encapsulated within Q.931 messages using H.225 (using Fast Connect) without the use of a separate H.245 TCP connection.

• H.450.2 Call Transfer without consultation and H450.3 Call Deflection provide a limited subset of features to support Internet call waiting

• H.235 security allows only duly authorized and authenticated gateways to access Gatekeeper resources.

• Translation of FXS hookflash to H.245 user input along with the previously suggested translation of H.245 user input to FXO hookflash provides end-to-end hookflash relay in FXS-to-FXO configurations.

• Gatekeeper Transaction Message Protocol (GKTMP) for the Cisco Gatekeeper with a corresponding user API for the UNIX environment, which allows a third party to develop elements to control and utilize a Gatekeeper for applications beyond what is directly supported in Cisco IOS Release 12.1(1)T.

• Cisco Gatekeeper supports the Gatekeeper MIB, which allows SNMP management.

• Gateway support for the Alternate Endpoint field in ACF allows third-party Gatekeepers to provide more robust call establishment.

• Gateway support for network-based billing number on a per-interface basis allows third-party Gatekeepers to obtain per-call interface usage information for billing or other purposes.

• Gateway support for the voice-port description allows third-party gatekeepers to obtain customer-specific, per-call interface usage information for billing or other purposes.

Restrictions

H.323 Version 2 Phase 2 features will not interoperate with H.323 Version 1 features in Cisco IOS releases earlier than 11.3(9)NA or 12.0(3)T. Earlier Cisco IOS releases contain H.323 Version 1 software that does not support protocol messages with an H.323 Version 2 protocol identifier.

Note All systems must be running either Cisco IOS release 11.3(9)NA and later releases or Cisco IOS version 12.0(3)T and later releases to interoperate with H.323 Version 2.

To use H.450 services (Call Transfer or Call Deflection), you must use Release 12.1(1)T of the Gatekeeper; H.450 on the gateways is incompatible with previous releases of the Cisco Gatekeeper.

If you are planning to use a Cisco AS5300 universal access server, your software requires VCWare Version 4.04.

Related Features and Technologies

Cisco H.323 Version 2 technologies are typically configured by using a number of available compression and decompression (CODECs) and the following high-density DSP/voice modules.

Related Documents

• Multiservice Applications Configuration Guide

• Multiservice Applications Command Reference

• Voice over IP Quick Start Guide

• Voice over IP for the Cisco 3600 Series documentation

• Voice over IP for the Cisco AS5300 documentation

• Cisco Gatekeeper External Interface Reference

The following table lists the documentation available for configuring and using Cisco IOS H.323 Gatekeepers, gateways, and proxies:.

Document	Release	2500 Series	2600 Series	3600 Series	AS5300
Multimedia Conference Manager (Configuration )	11.3NA	x		x
Multimedia Conference Manager (Command Reference )	11.3NA	x		x
Configuring H.323 VoIP Gateway for Cisco Access Platform s	11.3(7)NA	x		x	x
Using Cisco 3600 and Cisco 2600 Series Routers as H.323 VoI P Gateways	12.0(2)XD		x	x	x

Supported Platforms

The Gatekeeper and proxy features apply to the following platforms:

• Cisco 2500 Series

• Cisco 2600 Series

• Cisco 3600 Series

• Cisco 7200 Series

• Cisco MC3810 MultiService Concentrator

The gateway features apply to the following platforms:

• Cisco uBR920

• Cisco 1700 Series

• Cisco 2600 Series

• Cisco 3600 Series

• Cisco 7200 Series

• Cisco 7500 Series

• Cisco AS5300

• Cisco AS5800

Supported Standard MIBs and RFCs

No new MIBs are supported by this feature. No RFCs are supported by this feature.

This feature provides support for the following ITU-T Recommendations:

• ITU-T Recommendation H.225.0, Cell Signaling Protocols and Media Stream Packetization for Packet Based Multimedia Communications Systems, version 2, March 1997.

• ITY-T Recommendation H.245, Control Protocol for Multimedia Communication, version 3, February 1998.

• ITU-T Recommendation H.323, Packet-Based Multimedia Communications Systems, version 2, February 1998.

• ITU-T Recommendation H. 235, Security and Encryption for H-Series (H.323 and other H.245-based) multimedia terminals, February 1998.

• ITU-T Recommendation H.450.1, Generic Functional Protocol for the Support of Supplementary Services in H.323, February 1998.

• ITU-T Recommendation H.450.2, Call Transfer Supplementary Service for H.323, September, 1997.

• ITU-T Recommendation H.450.3, Call Diversion Supplementary Service for H.323, September, 1997.

Prerequisites

Before you can use H.323 Version 2 Phase 2 features, you must:

• Establish a working IP network. For more information about configuring IP, see the "IP Overview," "Configuring IP Addressing," and "Configuring IP Services" chapters in the Cisco IOS Release 12.1 Network Protocols Configuration Guide, Part 1.

• Install the appropriate voice network module and voice interface card for your Cisco router. For more information about the physical characteristics of the voice network module, or how to install it, see the Voice Network Module and Voice Interface Card Configuration Note that came with your voice network module.

• Configure Voice over IP. For more information about configuring Voice over IP, see "Related Documents".

• Configure H.323 Gatekeepers, gateways, and proxies as needed. For more information about configuring these H.323 components, see "Related Documents".

• Configure a RADIUS AAA server to handle security for your network.

• Configure an NTP Server for your network.

Configuration Tasks

The H.323 Version 2 Phase 2 configuration options allow you to configure the H.323 components discussed in the following sections:

• Configuring H.323 Fast Connect

• Configuring H.245 Tunneling

• Configuring H.450

• Configuring a RADIUS/AAA Server

• Configuring the Gatekeeper

Configuring H.323 Fast Connect

Because Fast Connect is a H.323 Version 2 compliant feature and the majority of endpoints prefer to establish a call by using Fast Connect procedures, this feature is not configurable. H.323 Fast Connect does not require any additional configuration beyond a working voice configuration.

For more information about configuring voice ports, see "Configuring Voice Ports" in the Cisco IOS Release 12.0 Voice, Video, and Home Applications Configuration Guide.

Configuring H.245 Tunneling

The dtmf-relay command configured on the outgoing VoIP dial peer initiates H.245 tunneling procedures from a Fast Connect call. Note that H.245 tunneling will be activated only if dtmf-relay "h245-alpha" or "h245-signal" (but not "cisco-rtp") are configured on the VoIP dial peer.

Configuring H.450

How you configure a Cisco gateway for H.450 depends upon whether you want your gateway to:

• Redirect an unanswered call (Call Deflection).

• Transfer an answered call to a new DN (Call Transfer without consultation)

Although there are no new CLI commands for configuring H.450 services, the services are enabled only when a TCL/IVR Session Application is configured. Therefore, to use H.450 services, you must configure a TCL/IVR-based "application" on each applicable incoming dial peer for each Cisco Gateway that will be involved in Call Transfer or Call Deflection. If no special TCL/IVR behavior is required, you can use the standard TCL/IVR application "session." This is not to be confused with application "SESSION," which is not TCL/IVR-based and does not support H.450 services.

In addition, if Call Deflection is to be initiated from a QSIG PRI, you must configure the PRI for "isdn switch-type primary-qsig" and "isdn alert end-to-end." See the examples that follow.

Note For general information on configuring dial peer application and the meaning of incoming dial peer, please refer to Voice over IP for the Cisco AS5300 .

Configuring Call Deflection

An example configuration is shown in Figure 2.

Figure 2: H.450 Configuration to Redirect Unanswered Calls

Configuring Call Transfer Without Consultation

An example configuration is shown in Figure 3.

Figure 3: H.450 Configuration for Calls Transfer Without Consultation

Configuring Voice-Port Descriptions

The voice-port description feature uses the existing description subcommand for the voice port. When you configure the voice-port description, the exact contents of the description field are included in the ARQ message sent from the ingress gateway.

Note Configuring the voice-port description has no effect for calls that are not configured to use RAS.

To configure the description on a voice-port, follow these steps:

	Command	Purpose
Step 1	Router# config terminal	Enter global configuration mode.
Step 2	Router(config)# voice-port voice_port_ID	Enter voice-port configuration mode for the specified voice port.
Step 3	Router(config-voiceport)# description string	Defines the description associated with the voice-port.

Configuring a RADIUS/AAA Server

To configure the RADIUS/AAA server with information about the Gatekeeper for your network installation, follow these steps:

	Command	Purpose
Step 1	Router(config)# aaa new-model	Initiates the AAA script.
Step 2	Router(config)# aaa authentication login h323 group radius	Configures the router to use the H.323 method list for authentication purposes.
Step 3	Router(config)# radius-server deadtime seconds	Defines a threshold time in seconds until the router assumes the RADIUS server is dead. After 120 seconds, the router sends messages alerting an administrator about a security problem.
Step 4	Router(config)# radius-server host ip-address auth-port port-num acct-port port-num	Sets the server host IP address and the ports for both the authentication service and the accounting service.
Step 5	Router(config)# radius-server key testing123	Configure the radius key secret.

In addition to the above configuration, make sure that the following information is configured in your CiscoSecure AAA server:

• In the /etc/raddb/clients file, ensure that the following information is provided:

#Client Name            Key 
#-----------       ------------------- 
gk215.cisco.com         testing123 
 

Where:

gk215.cisco.com is resolved to the IP address of the Gatekeeper requesting authentication

and

taeduk@cisco.com is the h323-id of the gateway authenticating to Gatekeeper gk215.cisco.com.

• In the /etc/raddb/users file, ensure that the following information is provided:

taeduk@cisco.com  Password = "thiswouldbethepassword" 
User-Service-Type = Framed-User, 
Login-Service = Telnet 

Configuring the Gatekeeper

With this version of the Gatekeeper software, you can configure the Gatekeeper for interaction with external applications. Make sure that you include a priority value for selecting between multiple gateways when you configure the Gatekeeper. To configure the Gatekeeper, perform the tasks discussed in the following sections:

• Configuring a Dialing Prefix for each Gateway

• Configuring a Gatekeeper for Interaction with External Applications

• Configuring Triggers for External Applications

Configuring a Dialing Prefix for each Gateway

To put all your gateways in the same zone use the gw-priority argument and specify which gateways are used for calling different area codes. For example:

router(config-gk)# zone local localgk xyz.com
router(config-gk)# zone prefix localgk 408.......
router(config-gk)# zone prefix localgk 415....... gw-pri 10 gw1 gw2
router(config-gk)# zone prefix localgk 650....... gw-pri 0 gw1
 

In the above commands the following is accomplished:

• Domain xyz.com is assigned to Gatekeeper localgk.

• Prefix 408 is assigned to Gatekeeper localgk, and no gateway priorities are defined for it; therefore, all gateways registering to localgk can be used equally for calls to the 408 area code. No special gateway lists are built for the 408. prefix; a selection is made from the master list for the zone.

• The prefix 415 is added to Gatekeeper localgk, and priority 10 is assigned to gateways gw1 and gw2.

• Prefix 650 is added to Gatekeeper localgk, and priority 0 is assigned to gateway gw1.

• A priority 0 is assigned to gateway gw1 to exclude it from the gateway pool for prefix 650. When gw2 registers with Gatekeeper localgk, it is added to the gateway pool for each prefix as follows:

  • For gateway pool for 415, gateway gw2 is set to priority 10.

  • For gateway pool for 650, gateway gw2 is set to priority 5.

Configuring a Gatekeeper for Interaction with External Applications

There are two ways of configuring the Gatekeeper for interaction with an external application. You can configure a port number where the Gatekeeper listens for dynamic registrations from applications. Using this method, the application connects to the Gatekeeper and specifies the trigger conditions in which it is interested.

The second method involves using the CLI to statically configure the information about the application and its trigger conditions, in which case the Gatekeeper initiates a connection to the external application.

This configuration is for a Gatekeeper (sj.xyz.com) that uses port 20000 for a specific connection with an external server (Server-123). Server-123 has a number of triggers that are used to maintain a database of active gateways, which are used for active call resolution. The configuration is as follows:

	Command	Purpose
Step 1	Router(config)# Gatekeeper	Access the Cisco IOS Gatekeeper configuration mode by entering the Gatekeeper command.
Step 2	Router(config)# server registration-port port-num	Establish the server registration port that is used for communication between sj.xyz.com and Server-123 by entering the server registration-port command.

Server-123 establishes a connection with Gatekeeper sj.xyz.com on port 20000 and sends a REGISTER RRQ message to Gatekeeper sj.xyz.com to express interest in all RRQs from voice gateways that support a technology prefix of 1# or 2#.

The following is an example of a registration message:

REGISTER RRQ
Version-id:1
From:Server-123
To:sj.xyz.com
Priority:2
Notification-Only:
Content-Length:29
 
t=voice-gateway
p=1#
p=2#
 

When Gatekeeper sj.xyz.com receives this message, the information supplied in the message is added to the trigger list. Then, when an endpoint registers with this Gatekeeper by using an RRQ that matches the specified trigger condition in the message, the Gatekeeper sends a notification to Server-123.

See the following example of an RRQ notification sent from the Gatekeeper to the server when the above trigger condition matches:

REQUEST RRQ
Version-id:1
From:sj.xyz.com
To:Server-123
Notification-Only:
Content-Length:89
 
c=I:171.69.136.205:1720
r=I:171.69.136.205:16523
a=H:gw3-sj
t=voice-gateway
p=1# 2#

Configuring Triggers for External Applications

To establish statically configured triggers on a router, follow these general steps:

	Command	Purpose
Step 1	Router(config)# Gatekeeper	Access the Cisco IOS Gatekeeper configuration mode by entering the Gatekeeper command.
Step 2	Router(config)# server trigger {arq | lcf | lrj | lrq | rrq | urq} gkid priority server-id server-ip_address server-port	Enter the trigger configuration mode and specify the RAS message type for a trigger, enter the server trigger command.
Step 3	Router(config)# info-only	If the trigger is to end qualifying messages on a notification-only basis, enter the info-only command.
Step 4	Router(config)# destination-info {e164 | email-id | h323-id} value	If you want to limit the qualifying message based upon the destination information, enter the destination-info command. Repeat this command for more destinations.
Step 5	Router(config)# redirect-reason value	If you want to limit the qualifying messages based upon the redirect reason, enter the redirect-reason command. Repeat this command for more destinations.
Step 6	Router(config)# remote-ext-address value	If you want to limit the qualifying messages based upon the remote extension address, enter the remote-ext-address command Repeat this command for more destinations.
Step 7	Router(config)# endpoint-type value	If you want to limit the qualifying messages based upon the endpoint type, enter the endpoint-type command. Repeat this command for more destinations.
Step 8	Router(config)# supported-prefix value	If you want to limit the qualifying messages based upon the supported prefix, enter the supported-prefix command. Repeat this command for more destinations.
Step 9	Router(config)# exit	When you have specified all the parameters for this trigger, exit trigger submode by entering the following command Repeat Steps 2 through 9 for each trigger that you want to define.

To remove a trigger, enter the no server trigger command. To temporarily suspend a trigger, enter the trigger configuration mode, as described in step 2, and enter the shutdown subcommand.

Configuration Examples

The configuration examples for H.450 and the GKTMP Gatekeeper are described in the following sections:

• Configuring H.450

• Configuring the Gatekeeper

Command Reference

This section documents new or modified commands for the Gatekeeper. All other commands used with this feature are documented in the Cisco IOS Release 12.0 command references.

• security token required-for

• server registration-port

• server trigger

• timing hookflash-input

• timing hookflash-output

• show Gatekeeper servers

• debug Gatekeeper server

In Cisco IOS Release 12.0(1)T or later releases, you can search and filter the output for show and more commands. This functionality is useful when you need to sort through large amounts of output, or if you want to exclude output that you do not need to see.

To use this functionality, enter a show or more command followed by the "pipe" character ( | ), one of the keywords begin, include, or exclude, and an expression that you want to search or filter on:

See the following example of the show atm vc command where the command output begins with the first line where the expression "PeakRate" appears:

For more information on the search and filter functionality, refer to the Cisco IOS Release 12.0(1)T feature module CLI String Search.

security token required-for

To configure the RAS messages so that the Gatekeeper checks for access tokens, enter the security token required-for command from the config-gk mode. To disable the Gatekeeper from checking for tokens in RAS messages, enter the no form of this command.

Syntax Description

registration	Requires the registering gateway to send an access token in the registration request to the Gatekeeper.
all	Requires the gateway to send an access token in registration and call setup messages to the Gatekeeper.

Defaults

No access token is required for authentication if the Gatekeeper is configured.

Command Modes

Gatekeeper configuration mode

Command History

Release	Modification
12.1(1)T	This command was first introduced.

Usage Guidelines

Use this command to configure the Gatekeeper to search for access tokens in RAS messages. These tokens are verified by an AAA server before the Gatekeeper responds. If you use the "registration" option, the Gatekeeper checks for tokens in all heavyweight RRQ messages. If you use the "all" option, the Gatekeeper also checks all ARQ messages---in addition to the RRQ messages.

By using the no option of the command the Gatekeeper stops checking for authentication tokens in RAS messages.

Note When you use this command to configure the Gatekeeper to check for tokens in RAS messages, heavyweight ARQ and RRQ messages are not forwarded to an external application even if ARQ or RRQ trigger conditions are met.

Examples

See the following example to configure a Gatekeeper to utilize an AAA server, enter the gateways that will be registering on the AAA security server, by entering the following commands:

Router# aaa new-model
Router(config)#aaa authentication login h323 group radius
Router(config)#radius-server deadtime 120
Router(config)#radius-server host 172.18.192.59 auth-port 1645 acct-port 1646 key lab
 

Related Commands

Command	Description
debug h225 ans1	Shows additional information about contents of H.225 RAS messages.
debug aaa auth	Shows information on AAA/TACACS+ authorization.
debug ras	Shows the types of addressing for RAS messages sent and received.

server registration-port

To configure the listener port for the server to establish a connection with the Gatekeeper, enter the server registration-port command from Gatekeeper mode. Enter the no form of this command to force the Gatekeeper to close the listening socket so that no more new registration takes place. However, existing connections between the Gatekeeper and the external applications are left open.

Syntax Description

port number

Specifies a single range of values from 1 through 65535 for the port number on which the Gatekeeper listens for external server connections

Defaults

The registration port of the Gatekeeper is not configured, so no external server can register with this Gatekeeper.

Command Modes

Gatekeeper configuration mode

Command History

Release	Modification
12.1(1)T	This command was first introduced.

Usage Guidelines

Use this command to configure a server registration port to poll for servers that want to establish connections with the Gatekeeper on this router.

Note The no form of this command forces the Gatekeeper on this router to close the listen socket, so it cannot accept more registrations. However, existing connections between the Gatekeeper and servers are left open.

Examples

See the following example of how a listener port for a server is established for connection with a Gatekeeper:

Router# server registration-port 20000

Related Commands

Command	Description
server trigger	Configure static server triggers for specific RAS messages to be forwarded to a specified server.

server trigger

To configure a static server trigger for external applications, enter the server trigger command from Gatekeeper mode. Enter the no form of this command to remove a single statically configured trigger entry. Enter the "all" form of the command to remove every static trigger you configured if you want to delete them all.

Syntax Description

all	Specified to delete all CLI configured triggers.
arq, lcf, lrj, lrq, rrq, urq	RAS message types. Use these message types to specify a submode in the Gatekeeper configuration mode where you configure a trigger for the Gatekeeper to act upon. Specify only one message type per server trigger command. There is a different trigger submode for each message type. Each trigger submode has its own set of applicable commands.
gkid	The local Gatekeeper identifier.
priority	The priority for each trigger. The range is from 1 through 20, with 1 being the highest priority.
server-id	The external application's ID number.
server-ipaddress	The server's IP address.
server-port	The port on which the Cisco IOS Gatekeeper listens for messages from the external server connection.

Defaults

No server triggers are set.

Command Modes

Configure from Gatekeeper mode.

Command History

Release	Modification
12.1(1)T	This command was first introduced.

Usage Guidelines

Use this command to configure a static server trigger. There are six different server triggers---one for each of the RAS messages. To configure a trigger, go to its submode where a set of subcommands are used to trigger a condition. See the following examples.

In ARQ submode, enter the following syntax:

router(config-gk)#server trigger arq gkid priority
                  server-id server-ipaddress 
                  server-port
router(config-gk-arqtrigg)#

In LCF submode, enter the following syntax:

router(config-gk)#server trigger lcf gkid priority
                  server-id server-ipaddress 
                  server-port
router(config-gk-lcftrigg)#
 

In LRJ submode, enter the following syntax:

router(config-gk)#server trigger lrj gkid priority
                  server-id server-ipaddress 
                  server-port
router(config-gk-lrjtrigg)#
 

In LRQ submode, enter the following syntax:

router(config-gk)#server trigger lrq <gkid> <priority>
                  <server-id> <server-ipaddress> 
                  <server-port>
router(config-gk-lrqtrigg)#
 

In RRQ submode, enter the following syntax:

router(config-gk)#server trigger rrq gkid priority
                  server-id server-ipaddress 
                  server-port
router(config-gk-rrqtrigg)#
 

In URQ submode, enter the following syntax:

router(config-gk)#server trigger urq gkid priority
                  server-id server-ipaddress 
                  server-port
router(config-gk-urqtrigg)#
 

The following options are available in all submodes:

info-only	Information only---no need to wait for acknowledgement.
shutdown	Enter this subcommand to temporarily disable a trigger. The Gatekeeper does not consult triggers in a shutdown state when determining what message to forward.

The destination-info command is under the ARQ, LRQ, LCF, and LRJ submode and has the following options:

destination-info		Configure destination-info to trigger one of the following conditions:
	e164	Configure an E.164 pattern.
	email-id	Configure an email ID.
	h323-id	Configure an H.323 ID.
	word	When configuring the e164 address option, the email-id option, or the h323-id option above, the E.164 address can end in a trailing `., `s, or `*'.

The redirect-reason command is under the ARQ and LRQ submodes and has the following options:

redirect-reason		Configure a redirect-reason to trigger on (range of 0 through 65535) with the following reserved values:
	0	Unknown reason.
	1	Call forwarding busy or called DTE busy.
	2	Call forwarded no reply.
	4	Call deflection.
	9	Called DTE out of order.
	10	Call forwarding by the call DTE.
	15	Call forwarding unconditionally.

The remote-ext-address command is under the LCF trigger submode and has the following options:

remote-ext-address		Configure remote extension addresses, with the following options:
	e164	Configure an E.164 pattern.
	word	When configuring the e164 address option, the email-id option, or the h323-id option above, the E.164 address can end in a trailing `., `s, or `*'.

The endpoint-type command is under the RRQ and URQ trigger submodes and has the following options:

endpoint-type		Configure the type of endpoint to trigger, with the following options:
	Gatekeeper	The endpoint is an H.323 Gatekeeper.
	h320-gateway	The endpoint is an H.320 gateway.
	mcu	The endpoint is a multipoint control unit (MCU).
	other-gateway	The endpoint is another type of gateway not specified on this list.
	proxy	The endpoint is a H.323 proxy.
	terminal	The endpoint is an H.323 proxy.
	voice-gateway	The endpoint is a voice gateway.

The supported-prefix command is under the RRQ and URQ submodes and has the following options:

supported-prefix		Configure the gateway technology prefix to trigger on.
	word	Enter a word within the set of "0123456789#*" when configuring the E.164 pattern for a gateway technology prefix.

Entering the no form of the server trigger command removes the trigger definition from the Cisco IOS Gatekeeper with all statically configured conditions under that trigger.

Examples

See the following example to configure a server trigger on Gatekeeper sj.xyz.com to notify external server "Server-123" of any call to an E.164 number that starts with 1800 followed by any 7 digits (1800551212, for example):

Router# Gatekeeper
Router(config-gk)# server trigger arq sj.xyz.com 1 Server-123 1.14.93.130 1751
Router(config-gk-arqtrigg)#destination-info e164 1800.......
Router(config-gk-arqtrigg)#exit

Related Commands

Command	Description
server registration port	Configure a Gatekeeper listening port to listen for external server connections.
show Gatekeeper servers	Show a list of currently registered and statically configured triggers on this Gatekeeper router.

timing hookflash-input

Enter the timing hookflash-input command from privileged EXEC mode to specify the maximum duration of a hookflash for an FXS interface. Enter the no form of this command to restore the default duration for hookflash timing.

Syntax Description

milliseconds

Specifies the duration of the hookflash. Possible values are 50 through 1550.

Defaults

Default value is 600 milliseconds.

Command Modes

Privileged EXEC

Command History

Release	Modification
12.1(1)T	This command was introduced.

Usage Guidelines

This command does not affect whether hookflash relay is enabled; hookflash relay is only enabled when dtmf-relay h245-signal is configured on the applicable VoIP dial peers. Hookflash is relayed by using an h245-signal indication and can be sent only when h245-signal is available.

Enter the timing hookflash-input command on FXS interfaces to specify the maximum duration (in milliseconds) of a hookflash indication. If the hookflash lasts longer than the specified limit, then the FXS interface processes the indication as an on-hook. To set hookflash timing parameters for analog voice interfaces, use the voice-port timing subcommand.

Examples

To implement timing for the hookflash with a duration of 200 milliseconds, see the following example:

Router# configure terminal
Router(config)# voice-port 1/0/0
Router(config-voiceport)# timing hookflash-input 200

Related Commands

Command	Description
voice-port	Switch to the voice-port configuration mode from the global configuration mode.

timing hookflash-output

Enter the timing hookflash-output command to specify the duration of hookflash indications that the gateway generates on an FXO interface. Enter the no form of this command to restore the default duration for hookflash timing.

Syntax Description

milliseconds

Specifies the duration of the hookflash. Possible values are 50 through 1550.

Defaults

Default value is 400 milliseconds.

Command Modes

Privileged EXEC

Command History

Release	Modification
12.0(6)T	This command was introduced.
12.1(1)T	The default value was changed.

Usage Guidelines

This command does not affect whether hookflash relay is enabled; hookflash relay is only enabled when dtmf-relay h245-signal is configured on the applicable VoIP dial peers. Hookflash is relayed by using an h245-signal indication and can be sent only when h245-signal is available

Enter the timing hookflash-output command on FXO interfaces to specify the duration (in milliseconds) of a hookflash indication. To set hookflash timing parameters for analog voice interfaces, use the voice-port timing subcommand.

Examples

To implement timing for the hookflash with a duration of 200ms, see the following example after you have configured voice-port 1/0/0:

Router# configure terminal
Router(config)# voice-port 1/0/0
Router(config-voiceport)# timing hookflash-output 200

Related Commands

Command	Description
voice-port	Switch to the voice-port configuration mode from the global configuration mode.

show Gatekeeper servers

Enter the show Gatekeeper servers command to see a list of currently registered and statically configured triggers on this Gatekeeper router.

Syntax Description

gkid	(Optional) The local Gatekeeper name to which this trigger applies.

Command Modes

EXEC

Command History

Release	Modification
12.0(6)T	This command was introduced.

Usage Guidelines

Enter this command to show all server triggers (whether dynamically registered from the external servers or statically configured from the command line interface) on this Gatekeeper. If gkid is specified, only triggers applied to the specified Gatekeeper zone appear. If gkid is not specified, server triggers for all local Gatekeeper zones on this router appear.

Examples

This example shows the operating information of the specified gk102 server:

Router# show Gatekeeper servers gk102
 
                GATEKEEPER SERVERS STATUS
                =========================
 
     Gatekeeper Server listening port:20000
 
     Gatekeeper-ID:gk102
     --------------------
     RRQ  Priority:1
       Server-ID:sj-server
       Server IP address:1.14.93.28:42387
       Server type:dynamically registered
       Connection Status:active
       Trigger Information:
         Supported Prefix:10#
         Supported Prefix:3#
     RRQ  Priority:2
       Server-ID:sf-server
       Server IP address:1.14.93.43:3820
       Server type:CLI-configured
       Connection Status:inactive
       Trigger Information:
         Endpoint-type:MCU
         Endpoint-type:VOIP-GW
         Supported Prefix:99#
     ARQ  Priority:1
       Server-ID:sj-server
       Server IP address:1.14.93.28:42387
       Server type:dynamically registered
       Connection Status:active
       Trigger Information:
         Destination Info:M:nilkant@zone14.com
         Destination Info:E:1800.......
         Redirect Reason:Call forwarded no reply
         Redirect Reason:Call deflection

Related Commands

Command	Description
debug Gatekeeper server	Trace all the message exchanges between the Cisco IOS Gatekeeper and the external applications. I Show any errors that occur in sending messages to the external applications or in parsing messages from the external applications.

debug Gatekeeper server

Enter the debug Gatekeeper server command from EXEC mode to trace all the message exchanges between the Cisco IOS Gatekeeper and the external applications. Show any errors that occur in sending messages to the external applications or in parsing messages from the external applications. Enter the no form of this command to disable debugging output.

Syntax Description

There are no arguments or keywords.

Defaults

Disabled.

Command Modes

EXEC

Command History

Release	Modification
12.1(1)T	This command was introduced.

Usage Guidelines

Use this command to see information about a Gatekeeper server.

Examples

This example shows debugging information about a Gatekeeper server

Router# debug Gatekeeper servers 
 
Router# show debug
  Gatekeeper:
    Gatekeeper Server Messages debugging is on
 

To turn the Gatekeeper server debugging message off, see the following example:

Router# no debug all 
 

or

Router# no debug Gatekeeper servers
 

Related Commands

Command	Description
show Gatekeeper server	Show information about the Gatekeeper servers configured on your network by ID.

Glossary

AAA---Authentication, authorization, and accounting. AAA is a suite of network security services that provides the primary framework through which access control can be set up on your Cisco router or access server.

CHAP---Challenge Handshake Authentication Protocol.

CODEC---Compression/decompression software.

DNS---Domain name system used in address translation to convert H.323 IDs, URLs, or e-mail IDs to IP addresses. DNS is also used to locate remote Gatekeepers and to translate names of network nodes into IP addresses or host names of administrative domains.

DNIS---Dialed number identification service (the called number). Feature of trunk lines where the called number is identified; this called number information is used to route the call to the appropriate service.

DTMF---Dual tone multi-frequency.

E1---European digital carrier facility used for transmitting data through the telephone hierarchy. The transmission rate for E1 is 2.048 megabits per second (Mbps).

E.164---International Telecommunication Union (ITU-T) recommendation for international telecommunication numbering. This recommendation provides the number structure and functionality for the three categories of numbers used for international public telecommunication; geographic areas, global services, and networks.

E&M---rEceive and transMit, or Ear and Mouth. Type of signaling originally developed for analog two-state voltage telephony using the ear and mouth leads; in digital telephony, uses two bits.

endpoint---An H.323 terminal or gateway. An endpoint can call and be called. It generates or terminates the information stream.

ESF---Extended Superframe. Framing type used on T1 circuits that consists of 24 frames of 192 bits each, with the 193rd bit providing timing and other functions. ESF is an enhanced version of SF format.

FXO---Foreign Exchange Office. A voice interface emulating a PBX trunk line to a switch or telephone equipment to a PBX extension interface.

FXS---Foreign Exchange Station. A voice interface for connecting telephone equipment, which emulates the extension interface of a PBX or the subscriber interface for a switch.

Gatekeeper---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 can provide other services to the H.323 terminals and gateways, such as bandwidth management and locating gateways. 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.

gateway---An H.323 endpoint on the LAN that provides real-time, two-way communication between H.323 terminals on the LAN, other ITU-T terminals in the WAN, or to another H.323 gateway. A gateway allows H.323 terminals to communicate with non-H.323 terminals by converting protocols. A gateway is the point where a circuit-switched call is encoded and repackaged into IP packets.

GKAPI---Gatekeeper Application Programming Interface.

GKTMP---Gatekeeper Transaction Message Protocol.

H.245---An ITU-T standard that describes H.245 endpoint control.

H.323---An 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.

H.450.2---Call transfer supplementary service for H.323.

H.450.3---Call diversion supplementary service for H.323.

hookflash---A brief on-hook condition that occurs during a call. The on-hook condition is not long enough to be interpreted as a signal to disconnect the call. You can create a hookflash indication by quickly depressing and then releasing the hook on your telephone.

ICW---Internet call waiting service.

IVR---Interactive voice response. Term used to describe systems that provide information in the form of recorded messages over telephone lines in response to user input in the form of spoken words or more commonly DTMF signaling.

ITU-T---International Telecommunications Union-Telecommunication Standardization Sector.

OSP---Open Settlement Protocol.

packet---Logical grouping of information that includes a header containing control information and (usually) user data. Packets are most often used to refer to network layer units of data.

POTS---Plain old telephone service. Basic telephone service supplying standard single line telephones, telephone lines, and access to the Public Switched Telephone Network.

PSTN---Public Switched Telephone Network. General term referring to the variety of telephone networks and services in place worldwide.

Q.931---ITU-T specification for signaling to establish, maintain, and clear ISDN network connections.

QSIG---Q (point of the ISDN model) signaling. A common channel signaling protocol based upon ISDN Q.931 standards for digital PBXs.

RRQ---Registration Request RAS message. This message type is sent from an H.323 endpoint to an H.323 gateway.

RTP---Real Time Transport protocol. See RFC 1889.

SF---Super Frame. Common framing type used on T1 circuits. SF consists of 12 frames of 192 bits each with the 193rd bit providing error checking and other functions. SF is superseded by ESF, but is still widely used. Also called D4 framing.

T1---Digital WAN carrier facility. T1 transmits DS 1-formatted data at 1.544 Mbps through the telephone switching network by using alternate mark inversion or B8ZS coding.

T1 trunk---Digital WAN carrier facility. See T1.

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 that generally refers to Cisco's standards-based (for example, H.323) approach to IP voice traffic.

zone---A collection of all terminals, gateways, and multipoint control units (MCUs) managed by a single Gatekeeper. A zone has only one Gatekeeper, can be independent of LAN topology, and can comprise multiple LAN segments that are connected by using routers or other devices.

For a list of other internetworking terms, see Internetworking Terms and Acronyms that accompanied your access server and is available on the Documentation CD-ROM and Cisco Connection Online (CCO) at the following URL: http://www.cisco.com/univercd/cc/td/doc/cisintwk/ita/index.htm.

Posted: Tue Apr 18 10:31:12 PDT 2000
Copyright 1989 - 2000©Cisco Systems Inc.