H.323 Version 2 Support + RAI
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Table Of Contents
Improved Gateway Selection Process
Gateway Resource Availability Reporting
Support for Single Proxy Configurations
Registration of E.164 Addresses for Gateway-Attached Devices
Tunneling of Redirecting Number Information Element
Related Features and Technologies
Supported Standard MIBs and RFCs
Gatekeeper Configuration Tasks
show gatekeeper gw-type-prefix
show call resource voice stats
show call resource voice threshold
H.323 Version 2 Support
Feature History
This feature module describes Cisco H.323 Version 2 Support. Included here is an overview of the feature including the benefits, the prerequisites, the supported platforms, the configuration tasks, and a command reference of new and changed commands.
This document includes the following sections:
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Supported Standard MIBs and RFCs
Feature Overview
Cisco H.323 Version 2 Support upgrades Cisco IOS software to comply with the mandatory requirements and several of the optional features of the version 2 specification. This upgrade enhances the existing Voice Over IP Gateway, the Multimedia Conference Manager (Gatekeeper and Proxy). Future releases will add additional H.323 Version 2 features to the Cisco IOS software.
H.323 Version 2 Compliance
Cisco H.323 Version 2 support enables gatekeepers, gateways, and proxies to send and receive all the required fields in H.323 v2 messages.
Lightweight Registration
Prior to H.323 Version 2, Cisco gateways reregistered with the gatekeeper every 30 seconds. Each registration renewal used the same process as the initial registration, even though the gateway was already registered with the gatekeeper. This generated considerable overhead at the gatekeeper.
H.323 version 2 defines a lightweight registration procedure that still requires the full registration process for initial registration, but uses an abbreviated renewal procedure to update the gatekeeper and minimize overhead.
Lightweight registration requires each endpoint to specify a TimeToLive (TTL) value in its Registration Request (RRQ) message. When a gatekeeper receives a RRQ message with a TTL value, it returns an updated TTL timer value in a Registration Confirmation (RCF) message to the endpoint. Shortly before the TTL timer expires, the endpoint sends an RRQ message with KeepAlive field set to TRUE, which refreshes the existing registration.
An H.323 v2 endpoint is not required to indicate a time-to-live in its registration request. If the endpoint does not indicate a time-to-live, the gatekeeper assigns one and sends it to the gateway in the RCF message. No configuration changes are permitted during a lightweight registration, so all fields other than the endpointIdentifier, gatekeeperIdentifier, tokens, and time-to-live are ignored. In the case of H.323v1 endpoints that cannot process the time-to-live field in the RCF, the gatekeeper probes the endpoint with IRQs for a predetermined grace period to see if the endpoint is still alive.
Improved Gateway Selection Process
Prior to H.323 version 2, the gatekeeper selected a destination gateway by choosing gateways defined with zone prefix commands. This command assigns a dialing prefix to a zone and allows the use of wildcards in the dialing prefix. In version 1, the gatekeeper simply matched the destination number with the longest match in the defined dialing prefixes, and randomly selected a gateway registered in that zone.
The H.323 version 2 software improves the gateway selection process as follows:
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The gatekeeper maintains a separate gateway list, ordered by priority, for each of its zone-prefixes. If a gateway does not have an assigned priority for a zone-prefix, it defaults to priority 5, which is the median. To explicitly bar the use of a gateway for a zone prefix, define it as having a priority 0 for that zone prefix.
When selecting gateways, the gatekeeper identifies a target pool of gateways by performing a longest zone-prefix match; then it selects from the target pool according to priorities and resource availability. If all high-priority gateways are busy, a low-priority gateway might be selected.
Gateway Resource Availability Reporting
To allow gatekeepers to make intelligent call routing decisions, the gateway reports the status of its resource availability to its gatekeeper. Resources that are monitored are DSO channels and DSP channels. In release 12.0(5)T,this feature is available only on the AS5300 platform.
The gateway reports its resource status to the gatekeeper using the RAS Resource Availability Indication (RAI). When a monitored resource falls below a configurable threshold, the gateway sends an RAI to the gatekeeper indicating that the gateway is almost out of resources. When the available resources then cross above another configurable threshold, the gateway sends an RAI indicating that the resource depletion condition no longer exists.
Resource reporting thresholds are configured by using the "resource threshold" command. The upper and lower thresholds are separately configurable to prevent the gateway from operating sporadically due to the availability or lack of resources.
Support for Single Proxy Configurations
In previous releases, the gatekeeper supported two-proxy and no-proxy call scenarios. The destination gatekeeper decided whether a call would be proxied or direct based on its zone configuration. The source gatekeeper would pick a proxy for its outbound calls only when the destination gatekeeper returned its inbound proxy in the location confirm message. This version of the gatekeeper software adds support for single-proxy calls and the option to independently configure proxies for inbound and outbound call scenarios.
Registration of E.164 Addresses for Gateway-Attached Devices
The H.323 version 2 gateway now supports the registration of fully-qualified E.164 numbers with the gatekeeper for phones connected directly to the gateway. To register these E.164 numbers, use the register command when configuring the gateway.
Tunneling of Redirecting Number Information Element
An incoming PRI SETUP message may contain either a Redirecting Number (RDN) Information Element (IE) or an Original Called Number (OCN) IE. These IEs indicate that the call has been redirected (forwarded), and that each message contains the following:
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OCN IE is a Nortel variant of the RDN IE.
The H.323 Version 2 gateway now propagates the entire RDN or OCN IE from an incoming PRI message into the H.225 SETUP message. The IE is encapsulated in the nonStandardData field within the UUIE of the H.225 SETUP message. The nonStandardData field can contain the encapsulated RDN or OCN IE and a tunneled QSIG message, or it can contain only the OCN or RDN. Cisco and other third-party H.323 endpoints can access the redirected information by decoding the nonStandardData field. In accordance with the H.225 specification, the nonStandardData is ignored by third-party endpoints and causes no interoperability problems.
For redirected PRI calls that are routed to a Cisco gateway, sent using H.323 to another Cisco Gateway, and exit the gateway using PRI, the RDN/OCN IE is tunneled from the source gateway to the destination gateway. The incoming PRI SETUP message is tunneled through H.323/H.225, and is encoded into the outgoing PRI SETUP message by the destination gateway.
Tunneling the RDN or OCN IE is important for applications such as Unified Messaging servers that need to know the telephone number that was originally dialed so as to access the correct account information.
DTMF-Relay
Dual-Tone Multifrequency (DTMF) is the tone generated on a touch-tone phone when you press keypad digits. During a call you might enter DTMF to access Interactive Voice Response (IVR) systems such as voicemail, automated banking services and so on.
In previous releases of IOS, DTMF is transported in the same way as voice. This approach can result in problems accessing IVR systems. While DTMF is usually transported accurately when using high-bitrate voice CODECs such as G.711, low-bitrate CODECs such as G.729 and G.723.1 are highly optimized for voice patterns, and tend to distort DTMF tones. As a result, IVR systems may not correctly recognize the tones.
DTMF relay solves the problem of DTMF distortion by transporting DTMF tones "out of band", or separate from the encoded voice stream. Cisco H.323 Version 2 support introduces three options for sending DTMF tones out of band. These are:
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If none of these options is selected, DTMF tones are transported inband, and encoded in the same way as voice traffic.
The "cisco-rtp" option sends DTMF tones in the same RTP channel as voice. However, the DTMF tones are encoded differently from the voice samples and are identified by a different RTP payload type code. Use of this method accurately transports DTMF tones, but since it is proprietary it requires the use of Cisco gateways at both the originating and terminating endpoints of the H.323 call.
The "h245-signal" and "h245-alphanumeric" options are modes of DTMF transport defined by the ITU H.245 standard. These methods separate DTMF digits from the voice stream and send them through the H.245 signalling channel instead of the RTP channel. The tones are transported in H.245 User Input Indication messages. The H.245 signalling channel is a reliable channel, so the packets transporting the DTMF tones are guaranteed to be delivered. However, because of the overhead of using a reliable protocol, and depending on network congestion conditions, the DTMF tones may be slightly delayed. This delay is not known to cause problems with existing applications.
The "h245-signal" option relays a more accurate representation of a DTMF digit than the "h245-alphanumeric" option, in that tone duration information is included along with the digit value. This information is important for applications that require you to press a key for a particular length of time. For example, one popular calling card feature allows you to break out of an existing call by pressing the (#) key for more than two seconds and then make a second call without having to hang up in between. This feature is beneficial because it allows you to avoid having to dial your access number and PIN code again, and it allows you to avoid access charges if you are charged for accessing an outside line as is common at hotels.
The "h245-alphanumeric" option simply relays DTMF tones as ASCII characters. For instance, the DTMF digit 1 is transported as the ASCII character "1". There is no duration information associated with tones in this mode. When the Cisco H.323 gateway receives a DTMF tone using this method, it will generate the tone on the PSTN interface of the call using a fixed duration of 500 ms. All H.323 version 2 compliant systems are required to support the "h245-alphanumeric" method, while support of the "h245-signal" method is optional.
The ability of a gateway to receive DTMF digits in a particular format and the ability to send digits in that format are independent functions. To receive DTMF digits from another H.323 endpoint using any of the methods described above, no configuration is necessary. The Cisco H.323 version 2 gateway is capable of receiving DTMF tones transported by any of these methods at all times.
However, to send digits out of band using one of these methods, two conditions must be met:
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You may enable more than one DTMF relay option for a particular dial peer. If you enable more than one option, and if the peer indicates that it is capable of receiving DTMF in more than one of these formats then the gateway will send DTMF using the method among the supported formats that it considers to be the most preferred. The preferences are defined as follows:
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If the peer is not capable of receiving DTMF in any of the modes that you have enabled, DTMF tones will be sent inband.
When the Cisco H.323 version 2 gateway is involved in a call to a Cisco gateway running a version of IOS prior to 12.0(5)T, DTMF tones will be sent inband since those systems do not support DTMF relay.
Hookflash Relay
A "hookflash" indication is a brief on-hook condition that occurs during a call. It 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 then 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 may 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. Since 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 "signal" structure with a value of "!". This value represents a hookflash indication.
Cisco H.323 Version 2 support includes limited support for relaying hookflash indications via H.245. H.245 User Input Indication messages containing hookflash indications that are received on the IP call leg are forwarded to the POTS call leg if the POTS interface is FXO. If the interface is not FXO, any H.245 hookflash indication that is received is ignored. This support allows IP telephony applications to send hookflash indications to a PBX through the Cisco gateway, and thereby invoke the PBX's supplementary services if the PBX supports access to those features via hookflash.
The gateway does not originate H.245 hookflash indications in this release. For example it does not forward hookflash indications from FXS interfaces to the IP network over H.245.
The acceptable duration of a hookflash indication varies by equipment vendor and by country. While one PBX may consider a 250 ms on-hook condition to be a hookflash, another PBX may consider this condition to be a disconnect. Therefore this release of IOS adds the "timing hookflash-out" command to allow the administrator to define the duration of a hookflash signal generated on an FXO interface.
CODEC Negotiation
CODEC negotiation allows the Gateway to offer several CODECs during the H.245 capability exchange phase and ultimately settle upon a single common CODEC during the call-establishment phase. This increases the probability of establishing a connection since there will be a greater chance of over-lapping audio capabilities between endpoints. Normally, only one CODEC can be specified when configuring a Dial-Peer, but CODEC negotiation allows you to specify a prioritized list of CODECs associated with a Dial-Peer. During the call-establishment phase the router will use the highest priority CODEC from the list which it has in common with the remote endpoint. It will also adjust to the CODEC selected by the remote endpoint so that a common CODEC is established for both the receive and transmit audio directions.
When a call is originated, all of the CODECs associated with the Dial-Peer are sent to the terminating endpoint in the H.245 Terminal Capability Set message. At the terminating endpoint, the gateway will advertise all of the CODECs that are available in firmware in its Terminal Capability Set. If there is a need to limit the CODECs advertised to a subset of the available CODECs, a terminating Dial-Peer must be matched which includes this subset. The "incoming called-number" command under the Dial-Peer can be used to force this match.
Benefits
Cisco H.323 Version 2 adds the following benefits to Cisco H.323 gatekeepers, gateways, and proxies:
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Restrictions
H.323 Version 2 features will not interoperate with H.323 Version 1 features in Cisco IOS versions prior to 11.3(9)NA or 12.0(3)T. Earlier Cisco IOS versions contain H.323 Version 1 software that does not support protocol messages with an H.323 Version 2 protocol identifier. All systems must be running either Cisco IOS version 11.3(9)NA and later or Cisco IOS version 12.0(3)T and later to interoperate with H.323 Version 2.
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 using a number of available compression/decompression (CODECs) and the following High Density DSP/Voice modules.
CODECs
The supported compression/decompression (CODECs) are available for use with Cisco H.323 Version 2. The following table lists each CODEC with a default packet size (in bytes) and a ranges.
High Density DSPs
The following platforms support Cisco H.323 with the following DSP/Voice modules:
Cisco 2600 Series
The Cisco 2600 series DSP/voice modules support the following sessions:
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Cisco 3600 Series
The Cisco 3600 series DSP/voice modules support the following sessions:
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Cisco 7200 Series
This Cisco 7200 series DSP/voice modules support the following sessions:
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Cisco AS5300 Universal Access Server
The Cisco AS5300 universal access server DSP/voice modules support the following sessions:
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Caution
Related Documents
The following documents describe how to configure Voice over IP:
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http://www.cisco.com/univercd/cc/td/doc/product/software/ios120/12cgcr/voice_c/index.htm
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http://www.cisco.com/univercd/cc/td/doc/product/software/ios120/12cgcr/voice_r/index.htm
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The following table lists the documentation available for configuring and using Cisco IOS H.323 gatekeepers, gateways, and proxies:
Supported Platforms
The gatekeeper and proxy features apply to the following platforms:
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The gateway features apply to these platforms.
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Supported Standard MIBs and RFCs
Standards
This feature adds support for the following ITU-T standards: H.323 Annex E and H.323 Annex G.
MIBs
No new or modified MIBs are supported by this feature.
To obtain lists of MIBs supported by platform and Cisco IOS release and to download MIB modules, go to the Cisco MIB web site on Cisco Connection Online (CCO) at http://www.cisco.com/public/sw-center/netmgmt/cmtk/mibs.shtml.
RFCs
No new or modified RFCs are supported by this feature.
Prerequisites
The Cisco AS5350 and Cisco AS5400 do not support the Mica Modem Card, Microcom Modem Card, or VoIP Feature Card. Voice and modem functions are provided by the Universal Port Dial Feature card running SPE firmware. See the Cisco AS5350 Universal Gateway Card Installation Guide and the Cisco AS5400 Universal Gateway Card Installation Guide for more information. All references to the Cisco AS5300 in this document apply to the Cisco AS5350 and Cisco AS5400 platforms with the following exceptions:
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Other Prerequisites
Before you can use the H.323 Version 2 features, you must do the following:
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Configuration Tasks
The H.323 Version 2 configuration options allow you to configure the following H.323 components:
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Note
For the Cisco AS5300 access server, port designation is port.
For the Cisco AS5350 and Cisco AS5400 universal gateways, port designation is slot/port.
For the Cisco AS5800 access server, port designation is shelf/slot/port.
CODEC Configuration Tasks
To configure multiple CODECs for a dial-peer, use these steps:
Step 1
The "voice class codec" command is used to create a CODEC preference list which is independent of a Dial-Peer and can be applied to several Dial-Peers.
Step 2
Router(config)#[no] voice class codec <tag>Router(config-class)#Step 3
Router(config-class)# [no] codec preference <value> <codec_type> [<cr> | bytes]<size> <cr>Step 4
Router(config-dial-peer)# voice-class codec <tag>Step 5
Here is a sample configuration:
Router# configure terminalEnter configuration commands, one per line. End with CNTL/Z.(config)#voice class codec 99(config-class)# codec preference 1 g711alaw(config-class)# codec preference 2 g711ulaw bytes 80(config-class)# codec preference 3 g723ar53(config-class)# codec preference 4 g723ar63 bytes 144(config-class)# codec preference 5 g723r53(config-class)# codec preference 6 g723r63 bytes 120(config-class)# codec preference 7 g726r16(config-class)# codec preference 8 g726r24(config-class)# codec preference 9 g726r32 bytes 80(config-class)# codec preference 10 g728(config-class)# codec preference 11 g729br8(config-class)# codec preference 12 g729r8 bytes 50(config-class)#end#Router(config)# dial-peer voice 1919 voip(config-dial-peer)#voice-class codec 99(config-dial-peer)#endRouter# show running-configdial-peer voice 1919 voipvoice-class codec 99!voice class codec 99codec preference 1 g711alawcodec preference 2 g711ulaw bytes 80codec preference 3 g723ar53codec preference 4 g723ar63 bytes 144codec preference 5 g723r53codec preference 6 g723r63 bytes 120codec preference 7 g726r16codec preference 8 g726r24codec preference 9 g726r32 bytes 80codec preference 10 g728codec preference 11 g729br8codec preference 12 g729r8 bytes 50
Gatekeeper Configuration Tasks
With this version of the gatekeeper software, you can configure the gatekeeper to do the following:
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Detailed instructions for proxy configuration are provided in the "use-proxy" command description. To learn how to configure dialing prefixes, see the "zone prefix" command description.
Gateway Configuration Tasks
This release of the gateway software allows you to configure an H.323 gateway as follows:
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For information on the "dtmf-relay" command, see the "dtmf-relay" command description. For information on the "timing hookflash-out" command, see the "timing hookflash-out" command description.
Configuration Examples
See the examples provided for each command in the "Gatekeeper Command Reference" section.
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.
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clear h323 gatekeeper call
To force a specific call or all calls currently active on the gatekeeper to disconnect, use the
clear h323 gatekeeper call EXEC command.clear h323 gatekeeper call {all | local-callID local-CallID}
Syntax Description
Command Modes
EXEC
Command History
12.0(5)T
This command was introduced.
12.1(5)XM2
The command was introduced for the Cisco AS5350 and CiscoAS5400.
Defaults
None
Usage Guidelines
Force all calls on the gatekeeper to disconnect by using this command.
Examples
Use the following form of the clear h323 gatekeeper call command to force an active call with the local call ID of "12-3339" to disconnect:
clear h323 gatekeeper call local-callID 12-3339You can get information about specific active calls by using the show gatekeeper calls command.
The following example forces all active calls on this gatekeeper to be disconnected:
clear h323 gatekeeper call allRelated Commands
show gatekeeper calls
To show the status of each ongoing call that a gatekeeper is aware of, use the show gatekeeper calls EXEC command.
show gatekeeper calls
Syntax Description
This command has no arguments or keywords.
Command Modes
EXEC
Command History
11.3(2) NA
This command was introduced.
12.0(5) T
The display format was modified for H.323 V2.
12.1(5)XM2
The command was introduced for the Cisco AS5350 and CiscoAS5400.
Usage Guidelines
Use this command to show the status of all outgoing calls that the gatekeeper handles.
Examples
router# show gatekeeper callsTotal number of active calls = 1.GATEKEEPER CALL INFO====================LocalCallID Age(secs) BW12-3339 94 768(Kbps)Endpt(s):Alias E.164Addr CallSignalAddr Port RASSignalAddr Portsrc EP:epA 90.0.0.11 1720 90.0.0.11 1700dst EP:epB@zoneB.comsrc PX:pxA 90.0.0.01 1720 90.0.0.01 24999dst PX:pxB 172.21.139.90 1720 172.21.139.90 24999Related Commands
show gatekeeper endpoints
Display status of registered endpoints for a gatekeeper.
show gatekeeper gw-type-prefix
Display the gateway technology prefix table.
show gatekeeper endpoints
To display the status of all registered endpoints for a gatekeeper, use the show gatekeeper endpoints EXEC command.
show gatekeeper endpoints
Syntax Description
This command has no arguments or keywords.
Command Modes
EXEC
Command History
11.3(2) NA
This command was introduced.
12.0(5) T
The display format was modified for H.323 V2.
12.1(5)XM2
The command was introduced for the Cisco AS5350 and CiscoAS5400.
Usage Guidelines
Use this command to display the status of all registered endpoints for a gatekeeper.
Examples
Router#show gatekeeper endpointsCallsignalAddr Port RASSignalAddr Port Zone Name Type F--------------- ---- ------------- ----- ---------- ----- --172.21.127.8 1720 172.21.127.8 24999 sj-gk MCU H323-ID:joe@cisco.com172.21.13.88 1720 172.21.13.88 1719 sj-gk VOIP-GW O H323-ID:la-gw
Related Commands
show gatekeeper gw-type-prefix
To display the gateway technology prefix table, use the show gatekeeper gw-type-prefix EXEC command.
show gatekeeper gw-type-prefix
Syntax Description
This command has no arguments or keywords.
Command Modes
EXEC
Command History
11.3(2) NA
This command was introduced.
12.0(5) T
The display format was modified for H.323 V2.
12.1(5)XM2
The command was introduced for the Cisco AS5350 and CiscoAS5400.
Usage Guidelines
This command first appeared in the Cisco IOS Release 11.3 NA.
Examples
Following is a sample output for a gatekeeper which is controlling two local zones, "sj-gk" and "la-gk":
router#show gatekeeper gw-type-prefixGATEWAY TYPE PREFIX TABLE===========================Prefix:12#* (Default gateway-technology)Zone sj-gk master gateway list:172.21.13.11:1720 sj-gw1172.21.13.22:1720 sj-gw2 (out-of-resources)172.21.13.33:1720 sj-gw3Zone sj-gk prefix 408....... priority gateway list(s):Priority 10:172.21.13.11:1720 sj-gw1Priority 5:172.21.13.22:1720 sj-gw2 (out-of-resources)172.21.13.33:1720 sj-gw3Prefix:7#* (Hopoff zone la-gk)Statically-configured gateways (not necessarily currently registered):1.1.1.1:17202.2.2.2:1720Zone la-gk master gateway list:171.69.127.11:1720 la-gw1171.69.127.22:1720 la-gw2
Related Commands
show gatekeeper zone status
To display the status of zones related to a gatekeeper, use the show gatekeeper zone status EXEC command.
show gatekeeper zone status
Syntax Description
This command has no arguments or keywords.
Command Modes
EXEC
Command History
11.3(2) NA
This command was introduced.
12.0(5)T
This display format was modified for H.323 V2.
12.1(5)XM2
The command was introduced for the Cisco AS5350 and CiscoAS5400.
Usage Guidelines
Use this command to display the status of all zones related to a gatekeeper.
Examples
router# show gatekeeper zone statusGATEKEEPER ZONES================GK name Domain Name RAS Address PORT FLAGS MAX-BW CUR-BW(kbps) (kbps)------- ----------- ----------- ---- ----- ------ ------sj.xyz.com xyz.com 1.14.93.85 1719 LS 0SUBNET ATTRIBUTES :All Other Subnets :(Enabled)PROXY USAGE CONFIGURATION :inbound Calls from germany.xyz.com :to terminals in local zone sj.xyz.com :use proxyto gateways in local zone sj.xyz.com :do not use proxyOutbound Calls to germany.xyz.comfrom terminals in local zone germany.xyz.com :use proxyfrom gateways in local zone germany.xyz.com :do not use proxyInbound Calls from all other zones :to terminals in local zone sj.xyz.com :use proxyto gateways in local zone sj.xyz.com :do not use proxyOutbound Calls to all other zones :from terminals in local zone sj.xyz.com :do not use proxyfrom gateways in local zone sj.xyz.com :do not use proxytokyo.xyz.co xyz.com 172.21.139.89 1719 RS 0milan.xyz.co xyz.com 171.69.57.90 1719 RS 0
Related Commands
use-proxy
Use the use-proxy command to enable proxy communications for calls between local and remote zones. The no use-proxy command has two forms and either removes a proxy configuration entry for a remote zone or disables proxy communications between local and remote zones.
use-proxy local-zone-name {default | remote-zone remote-zone-name}{inbound-to | outbound-from}{gateway | terminal}
no use-proxy local-zone-name remote-zone remote-zone-name [{inbound-to | outbound-from}{gateway | terminal}]
Syntax Description
Defaults
The local zone uses proxy for both inbound and outbound calls to and from the local H.323 terminals only. Proxy is not used for both inbound and outbound calls to and from local gateways.
Command Modes
Gatekeeper configuration
Command History
12.0(5)T
This command was first introduced.
12.1(5)XM2
The command was introduced for the Cisco AS5350 and CiscoAS5400.
Usage Guidelines
This command replaces the zone access command used in the previous versions of the gatekeeper. When a previous version of gatekeeper is upgraded, any zone access commands are translated to use-proxy commands. You can use the show gatekeeper zone status command to see the gatekeeper proxy configuration.
Examples
In the following example, the local zone, sj.xyz.com is configured to use a proxy for inbound calls from remote zones tokyo.xyz.com and milan.xyz.com to gateways in its local zone. The sj.xyz.com zone is also configured to use a proxy for outbound calls from gateways in its local zone to remote zones tokyo.xyz.com and milan.xyz.com:
use-proxy sj.xyz.com remote-zone tokyo.xyz.com inbound-to gatewayuse-proxy sj.xyz.com remote-zone tokyo.xyz.com outbound-from gatewayuse-proxy sj.xyz.com remote-zone milan.xyz.com inbound-to gatewayuse-proxy sj.xyz.com remote-zone milan.xyz.com outbound-from gatewaySince the default mode disables proxy communications for all gateway calls, only the gateway call scenarios listed above can use the proxy.
In the next example, the local zone, sj.xyz.com uses a proxy for only those calls that are outbound from H.323 terminals in its local zone to the specified remote zone germany.xyz.com:
no use-proxy sj.xyz.com default outbound-from terminaluse-proxy sj.xyz.com remote-zone germany.xyz.com outbound-from terminalNote that any calls inbound to H.323 terminals in the local zone sj.xyz.com from the remote zone germany.xyz.com use the proxy because the default applies.
The following example shows how to remove one or more proxy statements for the remote zone germany.xyz.com from the proxy configuration list:
no use-proxy sj.xyz.com remote-zone germany.xyz.comThe command above removes all special proxy configurations for the remote zone germany.xyz.com. After you enter a command like this, all calls between the local zone (sj.xyz.com) and germany.xyz.com are processed according to the defaults defined by any use-proxy commands that use the default option.
To prohibit proxy use for inbound calls to H.323 terminals in a local zone from a specified remote zone, enter a command similar to the following command:
no use-proxy sj.xyz.com remote-zone germany.xyz.com inbound-to terminalThis command overrides the default and disables proxy use for inbound calls from remote zone germany.xyz.com to all H.323 terminals in the local zone, sj.xyz.com.
Related Commands
show gatekeeper zone status
Display the status of all zones related to a gatekeeper.
zone prefix
To add a prefix to the gatekeeper zone list, use the zone prefix gatekeeper configuration command. To remove knowledge of a zone prefix, use the no form of this command with the gatekeeper name and prefix. To remove the priority assignment for a specific gateway, use the no form of this command with the gw-priority option.
zone prefix gatekeeper-name e164-prefix [gw-priority pri-0-to-10 gw-alias [gw-alias, ...]]
no zone prefix gatekeeper-name e164-prefix [gw-priority pri-0-to-10 gw-alias [gw-alias, ...]]
Syntax Description
Defaults
No knowledge of its own or any other zone's prefix is defined.
Command Modes
Gatekeeper configuration
Command History
Usage Guidelines
This command first appeared in Cisco IOS Releases 11.3(6)Q and 11.3(7)NA.
A gatekeeper can handle more than one zone prefix, but a zone prefix cannot be shared by more than one gatekeeper. If you have defined a zone prefix as being handled by a gatekeeper and now define it as being handled by a second gatekeeper, the second assignment cancels the first.
If you need a gatekeeper to handle more than one prefix, but for cost reasons you want to be able to group its gateways by prefix usage, there are two ways to do it.
The first method is simpler, has less overhead, and is recommended if your gateways can be divided into distinct groups, where each group is to be used for a different set of prefixes. For instance, if a group of gateways is used for calling area codes 408 and 650, and another group is used for calling area code 415, you can use this method. In this case, you define a local zone for each set of prefixes, and have the group of gateways to be used for that set of prefixes register with that specific local zone. Do not define any gateway priorities. All gateways in each local zone are treated equally in the selection process.
However, if your gateways cannot be cleanly divided into non-intersecting groups, (for instance if one gateway is used for calls to 408 and 415 and another gateway is used for calls to 415 and 650, and so on), you can put all these gateways in the same local zone and use the gw-priority option to define which gateways will be used for which prefixes.
When choosing a gateway, the gatekeeper first looks for the longest zone prefix match; then it uses the priority and the gateway status to select from the gateways. If all gateways are available, the gatekeeper chooses the highest priority gateway. If all the highest priority gateways are busy (see the gateway resource threshold command), a lower priority gateway is selected.
Note
Examples
The following example shows how you can define multiple local zones for separating your gateways:
router(config-gk)# zone local gk408or650 xyz.comrouter(config-gk)# zone local gk415 xyz.comrouter(config-gk)# zone prefix gk408or650 408.......router(config-gk)# zone prefix gk408or650 650.......router(config-gk)# zone prefix gk415 415.......Now you can configure all the gateways to be used for area codes 408 or 650 to register with gk408or650 and all gateways to be used for area code 415 to register with gk415. On Cisco voice gateways, you can do this by using the h323 voip id command.
The following example shows how you can put all your gateways in the same zone but use the gw-priority argument to determine which gateways will be used for calling different area codes.
router(config-gk)# zone local localgk xyz.comrouter(config-gk)# zone prefix localgk 408.......router(config-gk)# zone prefix localgk 415....... gw-pri 10 gw1 gw2router(config-gk)# zone prefix localgk 650....... gw-pri 0 gw1The above commands accomplish the following tasks:
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A priority 0 is assigned to gateway gw1 to exclude it from the gateway pool for prefix 650........ When gateway gw2 registers with gatekeeper localgk, it is added to the gateway pool for each prefix as follows:
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To change gateway gw2 from priority 10 for zone 415....... to the default priority 5, enter the following command:
no zone prefix localgk 415....... gw-pri 10 gw2To change both gateways gw1 and gw2 from priority 10 for zone 415....... to the default priority 5, enter the following command:
no zone prefix localgk 415....... gw-pri 10 gw1 gw2In the preceding example, the prefix 415....... remains assigned to gatekeeper localgk. All gateways that do not specify a priority level for this prefix are assigned a default priority of 5. To remove the prefix and all associated gateways and priorities from this gatekeeper, enter the following command:
no zone prefix localgk 415.......Related Commands
Gateway Command Reference
This section documents new or modified commands for the gateway. All other commands used with this feature are documented in the Cisco IOS Release 12.0 command references.
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dtmf-relay
Use the dtmf-relay command to specify how an H.323 gateway relays DTMF tones through an IP network. Options allow the gateway to forward tones "out-of-band", or separate from the voice stream. The no form of this command removes all signaling options and transmits the DTMF tones as part of the audio stream.
dtmf-relay [cisco-rtp] [h245-signal] [h245-alphanumeric]
no dtmf-relay
Syntax Description
Defaults
DTMF tones are sent "inband", or left in the audio stream, unless you use this command.
Command Modes
EXEC
Command History
Usage Guidelines
The dtmf-relay command determines the outgoing format of relayed DTMF tones. The gateway automatically accepts all formats.
The gateway only sends DTMF tones in the format you specify if the remote device supports it. If the remote device supports multiple formats, the gateway chooses the format based on the following priority:
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Note
Examples
The following are two examples of the dtmf-relay command:
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Router# configure terminalRouter(config)# dial-peer voice 103 voipRouter(config-dial-peer)# dtmf-relay cisco-rtp h245-signalRouter(config-dial-peer)# endRouter#•
Router# configure terminalRouter(config)# dial-peer voice 103 voipRouter(config-dial-peer)# no dtmf-relayRouter(config-dial-peer)# endRelated Commands
dial-peer
Switch to the voice-port configuration mode form the global configuration mode.
register
Use the register dial peer command to configure a gateway to register or deregister a fully-qualified dial-peer E.164 address with a gatekeeper. The no form of this command deregisters an E.164 address.
register e164
no register e164
Syntax Description
This command has no keywords or arguments.
Defaults
No E.164 addresses are registered until you enter this command.
Command Modes
Dial-peer configuration
Command History
12.0(5)T
This command was first introduced.
12.1(5)XM2
The command was introduced for the Cisco AS5350 and CiscoAS5400.
Usage Guidelines
Use this command to register the E.164 address of an analog telephone line attached to an FXS port on a router. The gateway automatically registers fully-qualified E164 addresses. Use the no register e164 command to deregister an address. Use the register e164 command to register a deregistered address.
Before you automatically or manually register an E.164 address with a gatekeeper, you must create a dial peer (dial-peer command), assign an FXS port to the peer (port command), and assign an E.164 address by using the destination-pattern command. The E.164 address must be a fully-qualified address. For example, +5551212, 5551212, and 4085551212 are fully-qualified addresses; 408555.... is not. E.164 addresses are only registered for active interfaces, which are those that are not shutdown. If an FXS port or its interface is shut down, the corresponding E.164 address is deregistered.
Tips
Examples
The following command sequence places the gateway in dial-peer configuration mode, assigns a E.164 address to the interface, and registers that address with the gatekeeper:
gateway1(config)#dial-peer voice 111 potsgateway1(config)#port 1/0/0gateway1(config-dial-peer)#destination-pattern 5551212gateway1(config-dial-peer)#register e164The following commands deregister an address with the gatekeeper:
gateway1(config)#dial-peer voice 111 potsgateway1(config-dial-peer)#no register e164The following example shows that you must have a connection to a gatekeeper and define a unique E.164 address before you can register an address:
gateway1(config)#dial-peer voice 222 potsgateway1(config)#port 1/0/0gateway1(config-dial-peer)#destination 919555....gateway1(config-dial-peer)#register e164ERROR-register-e164:Dial-peer destination-pattern is not a full E.164numbergateway1(config-dial-peer)#no gatewaygateway1(config)#dial-peer voice 111 potsgateway1(config-dial-peer)#register e164ERROR-register-e164:No gatekeeperRelated Commands
resource threshold
Use the resource threshold command to configure a gateway to report H.323 resource availability to the gateway's gatekeeper. The no form of this command disables gateway resource-level reporting.
resource threshold [all] [high percentage-value] [low percentage-value]
no resource threshold
Syntax Description
Defaults
Reports low resources when 90 percent of resources are in use, and reports resource availability when resource use drops below 90 percent.
Command Modes
Gateway configuration.
Command History
12.0(5)T
This command was first introduced.
12.1(5)XM2
The command was introduced for the Cisco AS5350 and CiscoAS5400.
Usage Guidelines
The resource threshold command defines the resource load levels that trigger Resource Availability Indicator (RAI) messages. To view the monitored resources, enter the show gateway command.
The monitored H.323 resources include DSP channels and DS0s. Use the show call resource voice stats command to see the total amount of resources available for H.323 calls.
Note
See the dial-peer configuration commands for details on how to associate a dial peer with a PRI or CAS group.
When any monitored H.323 resources exceed the threshold level defined by the high parameter, the gateway sends an RAI message to the gatekeeper with the AlmostOutOfResources field flagged. This message reports high-resource usage.
When all gateway H.323 resources drop below the level defined by the low parameter, the gateway sends the RAI message to the gatekeeper with the AlmostOutOfResources field cleared.
When a gatekeeper can choose between multiple gateways for call completion, the gatekeeper uses internal priority settings and gateway resource statistics to determine which gateway to use. When all other factors are equal, a gateway that has available resources will be chosen over a gateway that has reported limited resources.
Examples
The following command defines the H.323 resource limits for a gateway:
gateway1(config-gateway)#resource threshold high 70 low 60Related Commands
show call resource voice stats
The show call resource voice stats command displays resource statistics for an H.323 gateway.
show call resou rce voice stats
Syntax Description
This command has no keywords or arguments.
Command Modes
Privileged EXEC
Command History
12.0(5)T
This command was first introduced.
12.1(5)XM2
The command was introduced for the Cisco AS5350 and CiscoAS5400.
Usage Guidelines
This command displays the H.323 resources that are monitored when the resource threshold command is used to configure and enable resource threshold reporting. The following table describes the resource statistics that appear:
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Examples
The following example shows the resource statistics for an H.323 gateway:
gateway1#show call resource voice statsResource Monitor - Dial-up Resource Statistics Information:DSP Statistics:Utilization: 0 percentTotal channels: 48Inuse channels: 0Disabled channels 0:Pending channels: 0Free channels: 48DS0 Statistics:Total channels: 0Addressable channels: 0Inuse channels: 0Disabled channels: 0Free channels: 0Related Commands
resource threshold
Configure a gateway to report H.323 resources.
show call resource voice threshold
Display threshold configuration settings and status for a H.323 gateway.
show call resource voice threshold
The show call resource voice threshold command displays the threshold configuration settings and status for an H.323 gateway.
show call resource voice threshold
Syntax Description
This command has no keywords or arguments.
Command Modes
Privileged EXEC
Command History
12.0(5)T
This command was first introduced.
12.1(5)XM2
The command was introduced for the Cisco AS5350 and CiscoAS5400.
Usage Guidelines
This command displays the H.323 resource thresholds that are configured with the resource threshold command.
Examples
The following example shows the resource threshold settings and status for an H.323 gateway:
gateway1#show call resource voice thresholdResource Monitor - Dial-up Resource Threshold Information:DS0 Threshold:Client Type: h323High Water Mark: 70Low Water Mark: 60Threshold State: initDSP Threshold:Client Type: h323High Water Mark: 70Low Water Mark: 60Threshold State: low_threshold_hitRelated Commands
resource threshold
Configure a gateway to report H.323 resources.
show call resource voice stats
Switch to the voice-port configuration mode form the global configuration mode.
show gateway
Use the show gateway command to display the current gateway status.
show gateway
Syntax Description
This command has no keywords or arguments.
Command Modes
Privileged EXEC
Command History
11.3(6) NA2
This command was introduced.
12.0(5)T
This display format was modified for H.323 V2.
12.1(5)XM2
The command was introduced for the Cisco AS5350 and CiscoAS5400.
Usage Guidelines
This command displays the current gateway status.
Examples
The following example shows the report that appears when the gateway is not registered with a gatekeeper:
gateway1#show gatewayGateway gateway1 is not registered to any gatekeeperGateway alias listH323-ID gateway1H323 resource thresholding is Enabled but NOT ActiveH323 resource threshold values:DSP: Low threshold 60, High threshold 70DS0: Low threshold 60, High threshold 70This next example indicates that an E.164 address has been assigned to the gateway:
gateway1#show gateGateway gateway1 is registered to Gatekeeper gk1Gateway alias listE.164 Number 5551212H323-ID gateway1This example shows the report that appears when the gateway is registered with a gatekeeper and H.323 resource threshold reporting is enabled with the resource threshold command:
gateway1#show gatewayGateway gateway1 is registered to Gatekeeper gk1Gateway alias listH323-ID gateway1H323 resource thresholding is Enabled and ActiveH323 resource threshold values:DSP: Low threshold 60, High threshold 70DS0: Low threshold 60, High threshold 70This example shows the report that appears when the gateway is registered with a gatekeeper and H.323 resource threshold reporting is disabled with the no resource threshold command:
gateway1#show gatewayGateway gateway1 is registered to Gatekeeper gk1Gateway alias listH323-ID gateway1H323 resource thresholding is DisabledRelated Commands
timing hookflash-out
Use the timing hookflash-out command to specify the duration of hookflash indications that the gateway generates on an FXO interface. The no form of this command resets hookflash to the default value.
timing hookflash-out duration
no timing hookflash-out
Syntax Description
A duration can be between 50 and 500 milliseconds.
Defaults
Default value is 300ms.
Command Modes
Privileged EXEC
Command History
12.0(5)T
This command was first introduced.
12.1(5)XM2
The command was introduced for the Cisco AS5350 and CiscoAS5400.
Usage Guidelines
This command specifies a duration of hookflash indications. Hookflash indications may be generated when relayed from an IP network during a VoIP call. Depending on the vendor and country, PBXs and switches vary in their definition of the duration of a hookflash. This command allows you to adjust the hookflash duration appropriately for your network.
Examples
To implement timing for the hookflash with a duration of 200ms, enter the following command syntax after you have configured voice-port 1/0/0:
Router# configure terminalRouter(config)# voice-port 1/0/0Router(config-voiceport)# timing hookflash-out 200Related Commands
voice-port
Switch to the voice-port configuration mode form the global configuration mode.
Glossary
CODEC—Compression/decompression software.
DTMF—Dual tone multi-frequency.
E.164—International Telecommunication Union (ITU-T) recommendation for international telecommunication numbering. This recommendation provides the number structure and functionality for the 3 categories of numbers used for international public telecommunication; geographic areas, global services, and networks.
endpoint—An H.323 terminal or gateway. An endpoint can call and be called. It generates and/or terminates the information stream.
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 and 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 at which a circuit-switched call is encoded and repackaged into IP packets.
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.323 RAS—Registration, admission, and status. The RAS signaling protocol performs registration, admissions, bandwidth changes, status and disengage procedures between the VoIP gateway and the gatekeeper.
hookflash—A brief on-hook condition that occurs during a call. It 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 then releasing the hook on your telephone.
ITU-T—International Telecommunications Union-Telecommunication Standardization Sector.
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. PSTN refers to the local telephone company.
QoS—Quality of service, which refers to the measure of service quality provided to the user.
RAI—Resource Availability Indicator. This message type is sent from an H.323 gateway to an H.323 gatekeeper to indicate the availability or unavailability of resources.
RRQ—Registration Request. This message type is sent from an H.323 endpoint to an H.323 gateway.
RTP—Real Time Transport protocol. See RFC 1889.
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.
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