Table Of Contents

H.323 Support

Contents

Prerequisites for H.323 Support

Restrictions for H.323 Support

Information About H.323 Support

H.323 features supported on the SBC

Separate H.245 Control Channel

Restrictions for Separate H.245 Control Channel

H.245 Passthrough

Restrictions for H.245 Passthrough

Slow Start Media Relay

Restrictions for Slow Start Media Relay

Codec Mappings

DTMF Interworking

Restrictions for DTMF Interworking

Transcoding

Restrictions for Transcoding

RAS Tech Prefix

Restrictions for RAS Tech Prefix

User Protocol Timer Control

Restrictions

T.38 Fax Relay

T.38 H.245 - SDP mapping

H.245 Mode Request

RAS Maximum Bit Rate

H.323 Annex D / T.38 Annex B Interoperability

Restrictions

Q.931/H.225 Passthrough

Call Proceeding Passthrough

Unsupported Messages

Privacy

Setting of Protocol Version

Q.931 / H.225 Base Passthrough Profile

Restrictions

H.323 Privacy

Restrictions and Limitations

Configuring H.323 Features

Configuring Separate H.245 Control Channel

Configuring RAS Tech Prefix

Configuring User Protocol Timer Control

Configuring H.323 Privacy

Configuring Separate H.245 Control Channel and RAS Tech Prefix: Example

Configuring User Protocol Timer Controls: Example

Additional References

Related Documents

Standards

MIBs

RFCs

Technical Assistance

H.323 Support

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In addition to SIP, the SBC now supports H.323, enabling multimedia products and applications from multiple vendors to interoperate, and allowing users to communicate without concern for compatibility.

H.323 is the international standard for multimedia communication over packet-switched networks, including local area networks (LANs), wide area networks (WANs), and the Internet. It was first defined by the International Communications Union (ITU) in 1996. The most recent version is H.323 version 5 (2003).

Feature History for H.323 Support

Release	Modification
Release 3.5.0	This feature was introduced on the Cisco XR 12000 Series Router.
Release 3.5.1	The H.323 Privacy feature was introduced.
Release 3.6.0	No modification.

Contents

This module contains the following sections:

•Prerequisites for H.323 Support

•Restrictions for H.323 Support

•Information About H.323 Support

•Configuring H.323 Features

•Additional References

Prerequisites for H.323 Support

•This feature requires basic understanding of H.323-related ITU standards, gatekeepers, and gateways. Gateways are responsible for edge routing decisions between the Public Switched Telephone Network (PSTN) and the H.323 network. Gatekeepers are used to group gateways into logical zones and perform call routing between them.

Restrictions for H.323 Support

The restrictions for H.323 support are listed per feature in this chapter and other H.323-related chapters in the guide.

Information About H.323 Support

H.323 is a suite of protocols and documents that includes the standards H.323, H.225.0, H.245, the H.450-series and the H.460-series documents. It supports T.120 for data collaboration and file transfer. Not all components of H.323 are mandatory as part of a standard H.323 system. For example, H.460.2, which describes number portability, is generally not used in enterprise video conferencing systems.

H.323 is used in Voice over Internet Protocol (VoIP), and IP-based video conferencing and serves a similar purpose to that of the Session Initiation Protocol (SIP). It was designed from the outset to operate over IP networks, primarily, though H.323 may also operate over other packet-switched networks. H.323 was designed with multipoint voice and video conferencing capabilities, though most users do not take advantage of the multipoint capabilities specified in the protocol.

H.323 is more mature than SIP, but lacks the flexibility of SIP. SIP is currently less defined, but has greater scalability which could ease the Internet application integration. Like SIP, H.323 is one of the world market leaders for transporting voice and video over networks around the world, with billions of minutes of voice traffic every month. The SBC supports both SIP and H.323, enabling multimedia products and applications from multiple vendors to interoperate, and allowing users to communicate without concern for compatibility.

H.323 features supported on the SBC

The following supported H.323 features are documented separately in this guide or represent part of standard Q.931/H.225 protocols:

•H.323/SIP Interworking (see chapter "H.323-SIP Interworking")—Interworking of a defined subset of SIP/H.323 call and media signaling.

•DNS config of signaling peer—This feature enables you to use the domain name instead of the IP address in an adjacency-signal-peer configuration.

•Hunting (see section "Hunting" in chapter "Implementing SBC Policies")—Enables the SBC to hunt for other routes or destination adjacencies in case of a failure. Hunting means the route is retried.

•Basic conferencing passthrough (this feature is part of Q.931/H.225 passthrough)—Passthrough of conferenceID and conferenceGoal. Conference is controlled by the 3rd party equipment, such as call manager. The SBC enables the conference to pass through all the conference-related information.

•H.450 passthrough (this feature is part of Q.931/H.225 passthrough)—Passthrough of H.450 elements between call legs.

The following supported H.323 features are documented in this chapter:

•Separate H.245 Control Channel

•H.245 Passthrough

•Slow Start Media Relay

•T.38 Fax Relay

•DTMF Interworking

•Transcoding

•RAS Tech Prefix

•User Protocol Timer Control

•T.38 Fax Relay

•Q.931/H.225 Passthrough

•H.323 Privacy

Separate H.245 Control Channel

The H.323 procedures require that the SBC sets up a separate H.245 control channel over TCP. This feature complements tunneled H.245 support, enabling the user to control whether to use tunneling or not.

The new feature enables the SBC to carry out an H.323-H.323 call, where two call legs can negotiate different H.245 transport mechanisms. Each call leg decides independently whether to use a separate H.245 control channel.

The SBC sets up separate H.245 control channels only when required in one of the following cases:

•The SBC has received a startH245 Facility

•The SBC needs to send out an H.245 message and tunneling is not available

The SBC never requests separate H.245 control channel while tunneling is available unless the "disable tunneling" CLI command is set (see section: "Configuring Separate H.245 Control Channel" below). The SBC does not connect to an H.245 address simply because the peer offered an h245Address.

The SBC does not offer an H.245 address until it needs to, performing the following:

•Where possible, the SBC connects to the peer instead.

•Where impossible, the SBC offers its own H.245 address in a startH245 Facility and waits for 10 seconds for the peer to connect. This timeout is not configurable.

Since H.323 v2 onwards has support for Facility reason startH245, support for this feature is assumed in all peer devices. If the peer requires an H.245 connection and one does not exist, the partner must use a startH245 Facility to induce the SBC to connect to it.

If there is no H.245 transport possible (tunneled or separate), and H.245 messages must be sent by the SBC, then the call is terminated.

On receipt of provisionalRespToH245Tunnelling, the SBC waits to determine the final tunneling outcome before attempting separate H.245. H.245 messages are queued at this point and sent once an H.245 transport becomes available.

In the event of an H.245 connection race, the SBC only disconnects if it looses. The partner must disconnect if it loses. Races are resolved by comparing the listen address/port (not the connection address/port).

Back-pressure is exerted at call scope, or connection scope when multiple calls share a connection. So, if call leg B cannot forward H.245 messages for some reason, call leg A's connection may exert TCP back pressure on the peer. If call leg A is doing H.245 tunneling, and sharing a Q.931 TCP connection with other calls, then the peer will experience back pressure on the other calls too.

The SBC tears down separate H.245 connections at the same point as their call by closing the relevant socket.

Restrictions for Separate H.245 Control Channel

•The SBC does not support a model, in which it induces the peers in an H.323-H.323 call to set up the H.245 TCP connection directly between themselves or to the DBE.

•No show command is provided to list the H.245 transport status on a per-adjacency or per-call basis.

•The H.245 security is not supported.

H.245 Passthrough

In media bypass, H.245 content is passed unmodified between two H.323 call legs (about media bypass see section "How Adjacencies Affect Media Routing" in the "Implementing SBC Adjacencies" chapter). Passthrough happens irrespective of whether an H.245 message is received over tunneled H.245 transport or a separate H.245 control channel, and does not require that both H.323 call legs use the same H.245 transport mechanism. This feature permits inserting an SBC between two H.323 devices without any change to the passing H.245 content.

This is achieved by passing through H.245 messages opaquely between the endpoints. The Fast Start request and response is passed through in the same way as mainline H.245. The only messages inspected by the SBC are fast start and logical channel signaling. These are used to derive the bandwidth used for the call.

Restrictions for H.245 Passthrough

•Configuration to block passthrough of certain messages or message elements is not included in this feature and is covered separately.

•In a media bypass call, no SDP appears in the billing records.

•The SBC does not support rate limiting of passed-through H.245 traffic, other than generic rate limiting of all signaling traffic.

Slow Start Media Relay

The SBC supports media relay (which is media pass through the DBE) of unidirectional H.245 channels. H.245 codec types are converted to Session Description Protocol (SDP) for the purposes of the DBE programming, transcoder programming, and billing. This is done using a codec mapping table (see "T.38 Fax Relay" below). When dealing with codec types, for which no SDP mapping exists, the SBE makes a best-effort attempt, and tries to find the best possible SDP match.

Inserting an SBC between two H.323 devices does not impact H.245 function (see "H.245 Passthrough"). For example, the SBC does not modify the logical channel numbers of H.245 channels in a media relay call. In a distributed DBE model, H.248 signals are used to establish the necessary media terminations on the DBE.

The SBC supports renegotiation of media, using H.245 procedures, such as:

•fax upspeed: where endpoints switch over from a low-bit-rate audio codec to G.711

•TCS=0: where one endpoint induces the other to temporarily close all of its channels

Switchover to T.38 fax is described below in "T.38 Fax Relay".

Restrictions for Slow Start Media Relay

•The SBC does not support bidirectional H.245 channels neither in fast start, nor Open Logical Channel Close (OLCs).

•DTMF interworking is not supported between different types of UserInputIndication.

•No user configuration is provided to control DTMF interworking, which is triggered solely by capability negotiation.

•No means are provided to block setup of a particular codec, nor to ignore an unknown codec. The best-effort function mentioned above is always enabled.

•The SBC does not support multipoint capabilities.

Codec Mappings

The following codec mappings are used by the SBC to represent H.245 codecs as SDP for the purpose of:

•billing records (media relay only)

•DBE programming (media relay only)

•bandwidth allocation (media relay and media bypass). The bandwidth here is calculated based on the SDP, not directly from the H.245.

H.245 codec	appears as:
g711Alaw64k	PCMA/8000
g711Ulaw64k	PCMU/8000
g722_64k	G722/8000
g7231	G723.1/80
g728	G728/8000
g729	G729/8000
g729AnnexA	G729/8000
g729wAnnexB	G729/8000
g729AnnexAwAnnexB	G729/8000
gsmHalfRate	GSM-HR/8000
gsmFullRate	GSM/8000
All other audio codecs	PCMU/8000 (the default codec)
T.38	See "T.38 Fax Relay"

Note the following:

•H.245 video and data codecs other than T.38 are not supported by the SBC either for media relay or media bypass.

•The subset of codecs supported for H.323/SIP interworking is much smaller (for more information see the "H.323-SIP Interworking" chapter)

DTMF Interworking

Dual-tone multi-frequency (DTMF) tones are used to transfer user requests. Different systems may support different forms of DTMF. The SBC enables the DTMF interworking between these systems.

For example, some non-standard H.323 devices do not support the lowest common denominator of alphanumeric UserInputIndication. Such devices can only signal DTMF through RFC2833 telephony events or as in-band media data. Other devices support UserInputIndication but not the RFC2833 telephony event.

If two such devices are deployed back to back, their only option is to send DTMF tones as it is done in-band media data. Deploying an SBC between them allows each side to send DTMF, using its supported signaled method, UserInputIndication on one side and RFC2833 on the other, with the SBC interworking between the two.

This function requires the SBE to program the DBE to enable interception and insertion of RFC2833 DTMF on a particular side of the call - the side facing the RFC2833-only device. The SBE and DBE then collaborate to transfer DTMF signaling between the H.245 control channel and the RTP steam.

DTMF interworking is negotiated through TerminalCapabilitySet. Therefore, the SBC must be capable of extending the TerminalCapabilitySet to advertise support for both alphanumeric and RFC2833 methods.

The new feature described in this section replaces all existing H.323 DTMF interworking functions. H.323 calls must support DTMF interworking between alphanumeric UserInputIndication and RFC2833. In this case, the SBE coordinates with the DBE to carry out DTMF insertion and interception in the RTP.

DTMF interworking is negotiated through TerminalCapabilitySet, not manual configuration. Therefore, the SBC must always advertise support for both alphanumeric and RFC2833 methods, if necessary by extending the TerminalCapabilitySet on its way through. (The exception is a TCS=0.)

Restrictions for DTMF Interworking

•Only the alphanumeric UserInputIndication method is supported for DTMF interworking.

•The SBE assumes that a peer, advertising any form of UserInputCapability is capable of sending and receiving alphanumeric DTMF.

•No manual configuration is provided to force DTMF interworking to occur.

•Detection or insertion of DTMF as in-band audio data is not supported.

Transcoding

This feature is an update to transcoding support to account for the addition of H.323 slow-start calls. The SBC supports transcoding of slow start calls, enabling communication between different endpoints with different codecs, which otherwise cannot communicate with each other. Two H.323 endpoints deployed back-to-back might fail to agree on a mutually acceptable codec.

A typical case might be where one side is insisting on a low-bandwidth codec (such as G.729) because of bandwidth constraints or administrative policy, and the other side only supports G.711. For example, if the calling party uses g711alaw and the callee uses G.729 annex B, the SBC can convert G.711alaw codec to g729 annex B codec and enable communication between the two. Once the SBC detects that codec negotiation is needed, it uses VISM in the Cisco MGX 8880 switch as its media gateway to perform the transcoding. Deploying the SBC between the endpoints, in conjunction with an MGX 8880 transcoder, allows such calls to succeed.

The previous releases supported a fast-start-only version of transcoding. This function is now replaced with an implementation of transcoding that is triggered off TerminalCapabilitySet.

Restrictions for Transcoding

•The decision whether to use a transcoder is taken once per call, and is not modified if endpoints issue updated TerminalCapabilitySets (including TCS=0).

•When transcoding is required, the SBC enforces symmetric codecs for the call.

•Transcoding is never invoked in a fast start call. If no channels are suitable, endpoints must drop to slow start at which point transcoding may be invoked.

•The only codecs supported for transcoding are G.711 and G.729, and the only transcoder tested with them is the Cisco MGX 8880 switch.

RAS Tech Prefix

A technology prefix is an optional H.323 standard-based feature, supported by gateways and gatekeepers, that enables more flexibility in call routing within an H.323 VoIP network. The gatekeeper uses technology prefixes to group endpoints of the same type together. Technology prefixes can also be used to identify a type, class, or pool of gateways. This feature provides per-adjacency configuration of RAS Tech Prefix and registers this prefix with the gatekeeper.

An H.323 adjacency may now be optionally configured with a single tech prefix consisting of 1-32 dialed digits. It publishes the tech prefix to the gatekeeper in the following field of the RRQ:

terminalType.gateway.protocol.voice.supportedPrefixes.

As with existing adjacency configuration, this field may not be changed while the adjacency is attached. This feature works in conjunction with existing SBC support for adding or removing digits on dialed numbers (see section "Number Manipulation" in the "Implementing SBC Policies" chapter).

Restrictions for RAS Tech Prefix

•This feature does not support zone prefixes, for example, registration of prefix AliasAddresses with the gatekeeper.

User Protocol Timer Control

H.323 standards recommends timers, timeout, and retry counts for various messages. Their values are not fixed and represent a range. The ability to define these values facilitates interworking between different devices. H.323 timers and retry counts can be now configured by the user at a global and per-adjacency level. Timers are expressed in seconds.

The following Q.931 / H.225 timers are configurable.

•Q.931/H.225 Setup timer T303

•Q.931/H.225 Establishment timer T301

•Q.931/H.225 Incoming call proceeding timer T310

The following RAS timeout and retry counts are configurable.

•GRQ

•RRQ

•URQ

•ARQ

•BRQ

•DRQ

•LRQ

The RAS RRQ TTL and keepalive times (governing lightweight RRQ behavior) are configurable. These two settings are interrelated. If the user configures unsafe values for a given adjacency, the SBE reverts to the defaults.

The adjacency retry timer is configurable, and can be used to automatically reattempt adjacency attachment when an adjacency fails for any reason.

The following timers are hardcoded:

•TCP shutdown timeout - when gracefully closing a TCP connection, the time allowed for remote closure before closing it ungracefully. The hardcoded value is 1 second.

•TCP connect timeout - time allowed before giving up on a TCP connection attempt to a remote peer. The hardcoded value is 1 second.

Restrictions

•Changing timer values or retry counts while adjacencies are attached is allowed, but does not affect timers' or gatekeeper's transactions that are already in progress.

•No facility is provided to configure all RAS timeouts at once.

•H.245 timers are not included here since they only run in interworking scenarios

•The SBC does not support the configuration of the following Q.931 / H.225 timers:

–Q.931/H.225 Overlap Sending timer T302

–Q.931/H.225 Overlap Receiving Timer T304

–Q.931/H.225 Status timer T322.

•The SBC does not support the configuration of the following RAS timers:

–IRQ

–IRR

–RAI

–SCI

T.38 Fax Relay

This feature provides support for media relay of T.38 fax. The following features are supported:

•Both fax-only and fax-plus voice calls.

•Switchover from voice to T.38 fax.

•T.38 relay over UDPTL only, and unidirectional H.245 channels only.

T.38 H.245 - SDP mapping

The T.38 H.245 - SDP mapping is shown below.

DataApplicationCapability

 application

  t38fax

   t38FaxProtocol             m=image 40000 {udptl | tcp} t38

   t38FaxProfile

    fillBitRemoval            a=T38FaxFillBitRemoval

    transcodingJBIG           a=T38FaxTranscodingJBIG

    transcodingMMR            a=T38FaxTranscodingMMR

    version                   a=T38FaxVersion:<digits>

    t38FaxRateManagement      a=T38FaxRateManagement:{localTCF | transferredTCF}

    t38FaxUdpOptions OPTIONAL

     t38FaxMaxBuffer          a=T38FaxMaxBuffer:<digits>

     t38FaxMaxDatagram        a=T38FaxMaxDatagram:<digits>

     t38FaxUdpEC              a=T38FaxUdpEC:{t38UDPFEC | t38UDPRedundancy}

    t38FaxTcpOptions OPTIONAL

     t38TCPBidirectionalMode  [no mapping]

  maxBitRate                  a=T38maxBitRate:<digits> (UDP only) 

The only parameters needed for media relay function are the port and the peak-bit rate, which are highlighted in the example. Therefore, the presence of a T.38 fax function causes the following SDP to be transmitted to the DBE:

m=image <remote T.38 port> udptl t38

a=T38maxBitRate:14400

For interworking scenarios, a complete mapping needs to be carried out. However, this is not supported in this release

H.245 Mode Request

Switchover from a voice to fax call is handled by a RequestMode exchange. In an H.323-H.323 call this exchange is passed through transparently between call legs without DBE signaling. This allows endpoints to coordinate replacement of audio with T.38 channels.

RAS Maximum Bit Rate

In accordance with H.323v5 standards, the SBC counts UDP but not TCP towards the maximum bit rate agreed with the gatekeeper.

H.323 Annex D / T.38 Annex B Interoperability

T.38 Annex B is a fast start only (no H.245) version of H.323 Annex D. Interoperation with Annex B nodes is not supported by the SBC.

Restrictions

•The SBC cannot be configured to advertise the "t38FaxAnnexbOnly" field of SupportedProtocols in RAS messages, and ignores this field on receipt.

•No support for TCP or SRTP transport.

•No support for bidirectional H.245 channel signaling.

Q.931/H.225 Passthrough

This feature enables message elements from Q.931 / H.225 to be passed through between two H.323 call legs. This section describes the "base passthrough profile" of the SBC, listing the parts of the Q.931/H.225 message that may be passed through.

The following conventions are used in the base passthrough profile:

•ASN.1 syntax for Q.931 / H.225 messages is reproduced in this document.

•The following tags are attached to ASN.1 subtrees, specifying the passthrough behavior.

–P = "passthrough". This subtree is passed opaquely between call legs.

–P*="passthrough with privacy implications". Similar to "P", but passing through this subtree may reveal information about an endpoint or a remote telephone number.

–B = "block". This subtree is unconditionally blocked by the SBC and any information contained in it is lost.

–SBC. This subtree is manipulated by the SBC. Typically, values are replaced by those local to the SBC.

Call Proceeding Passthrough

A Call Proceeding message is never passed through. However, fields from it are extracted and put into a Progress or Facility in the upstream call log.

•A Progress is used if the Call Proceeding contains a progress indicator.

•A Facility is used otherwise.

Unsupported Messages

The following Q.931 messages are not supported by the SBC either because they are forbidden in H.323 or because the SBC does not currently support their corresponding features.

•Status, Status Enquiry

•SetupAck

•Information

•Notify

•userInformation.

Privacy

Subtrees marked as "P*" - "passthrough with privacy implications" are automatically blocked if the outgoing call leg has privacy enabled in CAC policy. This automatic blocking cannot be overridden by configuration, therefore, the only way to have these fields pass through is to disable privacy.

Setting of Protocol Version

When passing through messages, the SBC sets the version of outgoing messages to the lower value of its own ASN.1 version from that received in the original protocol message.

Q.931 / H.225 Base Passthrough Profile

Q931Message

 protocolDiscriminator               SBC

 callReferenceValue                  SBC

 message

  setup

   sendingComplete                   P

   bearerCapability                  P

   facility                          P

   progressIndicator                 P

   progressIndicator31               P

   notificationIndicator             P

   display                           P*

   keypadFacility                    P

   signal                            P

   callingPartyNumber                SBC

   callingPartySubaddress            B

   calledPartyNumber                 SBC

   calledPartySubaddress             B

   redirectingNumber                 P*

   userUser

    h323-uu-pdu

     h323-message-body

      setup

       protocolIdentifier            SBC

       h245Address                   SBC

       sourceAddress                 SBC

       sourceInfo                    SBC

       destinationAddress            SBC

       destCallSignalAddress         SBC

       destExtraCallInfo             B

       destExtraCRV                  B

       activeMC                      P

       conferenceID                  P

       conferenceGoal                P

       callServices                  P

       callType                      B

       sourceCallSignalAddress       SBC

       remoteExtensionAddress        B

       callIdentifier                P

       h245SecurityCapability        B

       tokens                        B

       cryptoTokens                  B

       fastStart                     SBC

       mediaWaitForConnect           P

       canOverlapSend                B

       endpointIdentifier            P*

       multipleCalls                 SBC

       maintainConnection            SBC

       connectionParameters          P

       language                      P

       presentationIndicator         SBC

       screeningIndicator            SBC

       serviceControl                P

       symmetricOperationRequired    P

       capacity                      B

       circuitInfo                   SBC

       desiredProtocols              B

       neededFeatures                B

       desiredFeatures               B

       supportedFeatures             B

       parallelH245Control           B

       additionalSourceAddresses     B

     nonStandardData                 P

     h4501SupplementaryService       P

     h245Tunneling                   SBC

     h245Control                     SBC

     nonStandardControl              P

     callLinkage                     P

     tunnelledSignallingMessage      P

     provisionalRespToH245Tunneling  SBC

     stimulusControl                 P

     genericData                     P

    user-data                        P

  callProceeding

   bearerCapability                  P

   facility                          P

   progressIndicator                 SBC

   progressIndicator31               SBC

   notificationIndicator             P

   display                           P

   userUser

    h323-uu-pdu

     h323-message-body

      callProceeding

       protocolIdentifier            SBC

       destinationInfo               P*

       h245Address                   SBC

       callIdentifier                P

       h245SecurityMode              B

       tokens                        B

       cryptoTokens                  B

       fastStart                     SBC

       multipleCalls                 SBC

       maintainConnection            SBC

       fastConnectRefused            SBC

       featureSet                    B

     nonStandardData                 P

     h4501SupplementaryService       P

     h245Tunneling                   SBC

     h245Control                     SBC

     nonStandardControl              P

     callLinkage                     P

     tunnelledSignallingMessage      P

     provisionalRespToH245Tunneling  SBC

     stimulusControl                 P

     genericData                     P

    user-data                        P

  alerting

   bearerCapability                  P

   facility                          P

   progressIndicator                 SBC

   progressIndicator31               SBC

   notificationIndicator             P

   display                           P*

   signal                            P

   userUser

    h323-uu-pdu

     h323-message-body

      alerting

       protocolIdentifier            SBC

       destinationInfo               P*

       h245Address                   SBC

       callIdentifier                P

       h245SecurityMode              B

       tokens                        B

       cryptoTokens                  B

       fastStart                     SBC

       multipleCalls                 SBC

       maintainConnection            SBC

       alertingAddress               P*

       presentationIndicator         SBC

       screeningIndicator            SBC

       fastConnectRefused            SBC

       serviceControl                P

       capacity                      B

       featureSet                    B

     nonStandardData                 P

     h4501SupplementaryService       P

     h245Tunneling                   SBC

     h245Control                     SBC

     nonStandardControl              P

     callLinkage                     P

     tunnelledSignallingMessage      P

     provisionalRespToH245Tunneling  SBC

     stimulusControl                 P

     genericData                     P

    user-data                        P

  connect

   bearerCapability                  P

   facility                          P

   progressIndicator                 SBC

   progressIndicator31               SBC

   notificationIndicator             P

   display                           P*

   dateTime                          P

   connectedNumber                   P*

   connectedSubaddress               P*

   userUser

    h323-uu-pdu

     h323-message-body

      connect

       protocolIdentifier            SBC

       h245Address                   SBC

       destinationInfo               P*

       conferenceID                  P

       callIdentifier                P

       h245SecurityMode              B

       tokens                        B

       cryptoTokens                  B

       fastStart                     SBC

       multipleCalls                 SBC

       maintainConnection            SBC

       language                      P

       connectedAddress              P*

       presentationIndicator         SBC

       screeningIndicator            SBC

       fastConnectRefused            SBC

       serviceControl                P

       capacity                      B

       featureSet                    B

     nonStandardData                 P

     h4501SupplementaryService       P

     h245Tunneling                   SBC

     h245Control                     SBC

     nonStandardControl              P

     callLinkage                     P

     tunnelledSignallingMessage      P

     provisionalRespToH245Tunneling  SBC

     stimulusControl                 P

     genericData                     P

    user-data                        P

  progress

   bearerCapability                  P

   cause                             P

   facility                          P

   progressIndicator                 SBC

   progressIndicator31               SBC

   notificationIndicator             P

   display                           P*

   userUser

    h323-uu-pdu

     h323-message-body

      progress

       protocolIdentifier            SBC

       destinationInfo               SBC

       h245Address                   SBC

       callIdentifier                P

       h245SecurityMode              B

       tokens                        B

       cryptoTokens                  B

       fastStart                     SBC

       multipleCalls                 SBC

       maintainConnection            SBC

       fastConnectRefused            SBC

     nonStandardData                 P

     h4501SupplementaryService       P

     h245Tunneling                   SBC

     h245Control                     SBC

     nonStandardControl              P

     callLinkage                     P

     tunnelledSignallingMessage      P

     provisionalRespToH245Tunneling  SBC

     stimulusControl                 P

     genericData                     P

    user-data                        P

  releaseComplete

   cause                             SBC

   facility                          P

   notificationIndicator             P

   display                           P*

   signal                            P

   userUser

    h323-uu-pdu

     h323-message-body

      connect

       protocolIdentifier            SBC

       reason                        SBC

       callIdentifier                P

       tokens                        B

       cryptoTokens                  B

       busyAddress                   P*

       presentationIndicator         SBC

       screeningIndicator            SBC

       capacity                      B

       serviceControl                P

       featureSet                    B

     nonStandardData                 P

     h4501SupplementaryService       P

     h245Tunneling                   SBC

     h245Control                     SBC

     nonStandardControl              P

     callLinkage                     P

     tunnelledSignallingMessage      P

     provisionalRespToH245Tunneling  SBC

     stimulusControl                 P

     genericData                     P

    user-data

  facility

   facility                          P

   notificationIndicator             P

   display                           P*

   callingPartyNumber                P*

   calledPartyNumber                 P*

   userUser

    h323-uu-pdu

     h323-message-body

      facility

       protocolIdentifier            SBC

       alternativeAddress            B

       alternativeAliasAddress       P

       conferenceID                  P

       reason                        P

       callIdentifier                P

       destExtraCallInfo             P

       remoteExtensionAddress        P

       tokens                        B

       cryptoTokens                  B

       conferences                   P

       h245Address                   SBC

       fastStart                     SBC

       multipleCalls                 SBC

       maintainConnection            SBC

       fastConnectRefused            SBC

       serviceControl                P

       circuitInfo                   B

       featureSet                    B

       destinationInfo               P*

       h245SecurityMode              B

      empty

     nonStandardData                 P

     h4501SupplementaryService       P

     h245Tunneling                   SBC

     h245Control                     SBC

     nonStandardControl              P

     callLinkage                     P

     tunnelledSignallingMessage      P

     provisionalRespToH245Tunneling  SBC

     stimulusControl                 P

     genericData                     P

    user-data                        P

Restrictions

•Any message elements from Q.931 / H.225 that are not listed in this section cannot be passed through.

•Passthrough of security tokens is not supported.

H.323 Privacy

With the H.323 privacy feature, users can invoke identity hiding on Q.931/H.225 messages. When this feature is implemented, the SBC strips Q.931/H.225 message elements that reveal information about the remote caller or callee before passing them to the endpoints.

---

Note The Q.931/H.225 message elements that impact privacy are defined in the H.323 passthrough profile.

---

The SBC applies the privacy service to a message if it contains a privacy request submitted by a user, or if a CAC policy on the SBC is configured to enable privacy on a caller or callee basis. If, however, the privacy configuration fields are set to default values, then the SBC forwards the message to the next call leg without applying the privacy service to the message. You can also configure the SBC to provide the H.323 privacy service on a per-adjacency basis.

The SBC applies the following rules when providing the H.323 privacy service:

•If an H.323 adjacency is configured to allow private information, then the SBC does not apply privacy service even if an incoming message requests it or the CAC policy is configured to enable privacy.

•If an H.323 adjacency is not configured to allow private information, but a CAC policy is configured to enable privacy, then the SBC applies the privacy service to outgoing messages.

•If an incoming message requests the privacy service, but a CAC policy has not been configured to enable privacy, then the SBC applies the service if the adjacency is configured to apply the privacy service.

•If an incoming message requests the privacy service when both the CAC policy and the adjacency have not been configured to apply the privacy service, then the SBC does not apply the privacy service and allows the private information to pass through.

Restrictions and Limitations

•The SBC does not apply the H.323 privacy service to H.245 and RAS messages.

•Currently, the CAC policy for callee privacy is available for the H.323 signaling stack at "connect time", and only if a connectedNumber is present. As a result, the callee privacy service is not applied to the Q.931 protocol messages that pass through before or after a call is connected when a connectedNumber is not present. Due to this limitation, the SBC forwards the Q.931 Alerting, Q.931 Progress, and Q.931 Release Complete messages without applying the privacy service request to them.

•In an interworking call, the SBC only applies privacy requests based on the CAC policy.

Configuring H.323 Features

Configuring Separate H.245 Control Channel

This command disables tunneling on a per-adjacency basis, facilitating interoperability with existing devices that are confused by tunneling. The command controls both incoming and outgoing calls.

SUMMARY STEPS

1. configure

2. sbc service-name

3. sbe

4. adjacency h323 adjacency-name

5. h245 tunnel disable

6. commit

7. exit

DETAILED STEPS

	Command or Action	Purpose
Step 1	configure Example: RP/0/0/CPU0:router# configure	Enables the global configuration mode.
Step 2	sbc service-name Example: RP/0/0/CPU0:router(config)# sbc mysbc	Enters the mode of an SBC service. Use the service-name argument to define the name of the SBC.
Step 3	sbe Example: RP/0/0/CPU0:router(config-sbc)# sbe	Enters the mode of the signaling border element (SBE) function of the SBC.
Step 4	adjacency h323 adjacency-name Example: RP/0/0/CPU0:router(config-sbc-sbe)# adjacency h323 2651XM-5	Enters the mode of an SBE H.323 adjacency. Use the adjacency-name argument to define the name of the H.323 adjacency.
Step 5	h245 tunnel disable Example: RP/0/0/CPU0:router(config-sbc-sbe-adj-h323)# h245 tunnel disable	Disables tunneling on a per-adjacency basis, facilitating interoperability with existing devices that are confused by tunneling. The command controls both incoming and outgoing calls. The default is tunneling enabled.
Step 6	commit Example: RP/0/0/CPU0:router(config-sbc-sbe-adj-h323)# commit	Saves configuration changes. Use the commit command to save the configuration changes to the running configuration file and remain within the configuration session.
Step 7	exit Example: RP/0/0/CPU0:router(config-sbc-sbe-adj-h323)# exit	Exits the media address mode to the DBE mode.

Configuring RAS Tech Prefix

This feature provides per-adjacency configuration of RAS Tech Prefix and registers this prefix with the gatekeeper. RAS tech prefix may consist of 1-32 dialed digits.

SUMMARY STEPS

1. configure

2. sbc service-name

3. sbe

4. adjacency h323 adjacency-name

5. tech-prefix tech-prefix

6. commit

7. exit

DETAILED STEPS

	Command or Action	Purpose
Step 1	configure Example: RP/0/0/CPU0:router# configure	Enables the global configuration mode.
Step 2	sbc service-name Example: RP/0/0/CPU0:router(config)# sbc mysbc	Enters the mode of an SBC service. Use the service-name argument to define the name of the SBC.
Step 3	sbe Example: RP/0/0/CPU0:router(config-sbc)# sbe	Enters the mode of the signaling border element (SBE) function of the SBC.
Step 4	adjacency h323 adjacency-name Example: RP/0/0/CPU0:router(config-sbc-sbe)# adjacency h323 2651XM-5	Enters the mode of an SBE H.323 adjacency. Use the adjacency-name argument to define the name of the H.323 adjacency.
Step 5	tech-prefix tech-prefix Example: RP/0/0/CPU0:router(config-sbc-sbe-adj-h323)# tech-prefix 32#	Provides per-adjacency configuration of RAS Tech Prefix and registers this prefix with the gatekeeper. RAS tech prefix may consist of 1-32 dialed digits followed by a # sign. The default is no tech prefix.
Step 6	commit Example: RP/0/0/CPU0:router(config-sbc-sbe-adj-h323)# commit	Saves configuration changes. Use the commit command to save the configuration changes to the running configuration file and remain within the configuration session.
Step 7	exit Example: RP/0/0/CPU0:router(config-sbc-sbe-adj-h323)# exit	Exits the media address mode to the DBE mode.

Configuring User Protocol Timer Control

SUMMARY STEPS

1. configure

2. sbc service-name

3. sbe

4. h323 | adjacency h323 adjacency-name

5. adjacency timeout

6. h225 timeout

7. ras retry

8. ras rrq ttl

9. ras rrq keepalive

10. ras timeout

11. commit

12. exit

13. show services sbc sbc-name sbe h323 timers

DETAILED STEPS

	Command or Action	Purpose
Step 1	configure Example: RP/0/0/CPU0:router# configure	Enables the global configuration mode.
Step 2	sbc service-name Example: RP/0/0/CPU0:router(config)# sbc mysbc	Enters the mode of an SBC service. Use the service-name argument to define the name of the SBC.
Step 3	sbe Example: RP/0/0/CPU0:router(config-sbc)# sbe	Enters the mode of the signaling border element (SBE) function of the SBC.
Step 4	h323 | adjacency h323 adjacency-name Example: RP/0/0/CPU0:router(config-sbc-sbe)# adjacency h323 2651XM-5	Enters the mode of either all H.323 adjacencies or a specified H.323 adjacency. Use the adjacency-name argument to define the name of the H.323 adjacency.
Step 5	adjacency timeout Example: RP/0/0/CPU0:router(config-sbc-sbe-adj-h323)# adjacency timeout 10000	Defines the time in milliseconds, during which in case of failure to connect, the SBC keeps trying to reconnect to the remote signaling peer and receive keep-alive messages from it. The value range is 10000-30000.
Step 6	h225 timeout [establishment timeout value | proceeding timeout value | setup timeout value Example: RP/0/0/CPU0:router(config-sbc-sbe-adj-h323)# h225 timeout establishment 250000	Defines the time for waiting to receive H.225 messages. •establishment timeout value—h225 establishment state timeout value in milliseconds. The default is 180000. The value range is 30000-300000. •proceeding timeout value—h225 proceeding state timeout value in milliseconds. 10000. The value range is 1000-30000. •setup timeout value—h225 setup timeout value in milliseconds. The default is 4000. The value range is 1000-30000.
Step 7	ras retry [arq | brq | drq | grq | rrq | urq] retry count Example: RP/0/0/CPU0:router(config-sbc-sbe-adj-h323)# ras retry arq 2 ras retry brq 2 ras retry drq 2 ras retry rrq 2 ras retry urq 2	Defines the number of times trying to re-send RAS messages in case of failure to send the messages. •arq retry count—Number of times to retry an ARQ transaction. •brq retry count—Number of times to retry a BRQ transaction. •drq retry count—Number of times to retry a DRQ transaction. •grq retry count—Number of times to retry a GRQ transaction. •rrq retry count—Number of times to retry an RRQ transaction. •urq retry count—Number of times to retry a URQ transaction. The value range is 0-30.
Step 8	ras rrq ttl Example: RP/0/0/CPU0:router(config-sbc-sbe-adj-h323)# ras rrq ttl 100	Defines the time to live messages (TTL) in seconds for registration request (RRQ). The default is 60. The value range is 16-300.
Step 9	ras rrq keepalive Example: RP/0/0/CPU0:router(config-sbc-sbe-adj-h323)# ras rrq keepalive 100000	Defines the time in milliseconds for registration request (RRQ) keep-alive messages. The default is 45000. The value range is 15000-150000.
Step 10	ras timeout [arq | brq | drq | grq | rrq | urq] timeout Example: RP/0/0/CPU0:router(config-sbc-sbe-adj-h323)# ras timeout arq 1000 ras timeout brq 1000 ras timeout drq 1000 ras timeout grq 1000 ras timeout rrq 1000 ras timeout urq 1000	Defines the common timeout in milliseconds for all RAS messages. •arq timeout—Timeout value for an ARQ transaction. •brq timeout—Timeout value for an BRQ transaction. •drq timeout—Timeout value for an DRQ transaction. •grq timeout—Timeout value for an GRQ transaction. •rrq timeout—Timeout value for an RRQ transaction. •urq timeout—Timeout value for an URQ transaction. The default is 5000. The value range is 1000-45000. The default is 5000.
Step 11	commit Example: RP/0/0/CPU0:router(config-sbc-sbe-adj-h323)# commit	Saves configuration changes. Use the commit command to save the configuration changes to the running configuration file and remain within the configuration session.
Step 12	exit Example: RP/0/0/CPU0:router(config-sbc-sbe-adj-h323)# exit	Exits the H.323 global or specified adjacency mode.
Step 13	show services sbc service-name sbe h323 timers Example: RP/0/0/CPU0:router# show services sbc mysbc sbe h323 timers	Displays the values of all H.323 timers.

Configuring H.323 Privacy

This feature allows the SBC to apply the H.323 privacy service on outbound messages

SUMMARY STEPS

1. configure

2. sbc service-name

3. sbe

4. adjacency h323 adjacency-name

5. allow private info

6. privacy restrict outbound

7. commit

8. exit

DETAILED STEPS

	Command or Action	Purpose
Step 1	configure Example: RP/0/0/CPU0:router# configure	Enables the global configuration mode.
Step 2	sbc service-name Example: RP/0/0/CPU0:router(config)# sbc mysbc	Enters the mode of an SBC service. Use the service-name argument to define the name of the SBC.
Step 3	sbe Example: RP/0/0/CPU0:router(config-sbc)# sbe	Enters the mode of the signaling border element (SBE) function of the SBC.
Step 4	adjacency h323 adjacency-name Example: RP/0/0/CPU0:router(config-sbc-sbe)# adjacency h323 2651XM-5	Enters the mode of an SBE H.323 adjacency. Use the adjacency-name argument to define the name of the H.323 adjacency.
Step 5	allow private info Example: RP/0/0/CPU0:router(config-sbc-sbe-adj-h323)# allow private info	Configures the H.323 adjacency to allow private information on messages sent out by the adjacency even if the CAC policy is configured to apply privacy service or the user requests privacy service. The no version of this command configures the H.323 adjacency to stop allowing private information from being sent out by the adjacency.
Step 6	privacy restrict outbound Example: RP/0/0/CPU0:router(config-sbc-sbe-adj-h323)# privacy restrict outbound	Configures the H.323 adjacency to apply privacy restriction on outbound messages if the user requests the privacy service. The no version of this command configures the H.323 adjacency to allow private information messages sent out by the adjacency.
Step 7	commit Example: RP/0/0/CPU0:router(config-sbc-sbe-adj-h323)# commit	Saves configuration changes. Use the commit command to save the configuration changes to the running configuration file and remain within the configuration session.
Step 8	exit Example: RP/0/0/CPU0:router(config-sbc-sbe-adj-h323)# exit	Exits an SBE H.323 global or specified adjacency mode.

Configuring Separate H.245 Control Channel and RAS Tech Prefix: Example

configure

sbc mysbc

sbe

adjacency h323 h323-fxs-1b

signaling-address ipv4 88.110.128.13

signaling-port 1720

remote-address ipv4 10.0.0.0/8

signaling-peer 10.124.2.2

signaling-peer-port 1720

account h323-fxs-1b

tech-prefix 2#

h245-tunnel disable 

attach

commit

exit

Configuring User Protocol Timer Controls: Example

configure

sbc mysbc

sbe

adjacency h323 abcd 

adjacency timeout 10000 

h225 timeout establishment 40000

adjacency timeout 10000?         

h225 timeout ?

  establishment  h225 establishment state timeout value.

  proceeding     h225 proceeding state timeout value.

  setup          h225 setup timeout value.

h225 timeout proceeding 30000

h225 timeout setup 30000     

ras ?

  retry    RAS retry configuration.

  rrq      RRQ (Registration Request) configuration.

  timeout  RAS timeout configuration.

ras retry ?

  arq  Retry count for an ARQ transaction.

  brq  Retry count for an BRQ transaction.

  drq  Retry count for an DRQ transaction.

  grq  Retry count for an GRQ transaction.

  rrq  Retry count for an RRQ transaction.

  urq  Retry count for an URQ transaction.

ras retry arq 2 

ras retry brq 2 

ras retry drq 2 

ras retry rrq 2 

ras retry rrq 2 

ras rrq ?

  keepalive  Rate for keepalive msgs to refresh an H323 adjacency registration.

  ttl        TTL (time to live) value for an RRQ request.

ras rrq keepalive ?

  <15000-150000>  Keepalive refresh time in milliseconds - default: 45000 ras rrq 
keepalive 15000

ras rrq ttl ?          

  <16-300>  TTL value in seconds - default: 60 

ras rrq ttl 30 

adjacency timeout 30000 

ras timeout ?

  arq  Timeout value for an ARQ transaction.

  brq  Timeout value for an BRQ transaction.

  drq  Timeout value for an DRQ transaction.

  grq  Timeout value for an GRQ transaction.

  rrq  Timeout value for an RRQ transaction.

  urq  Timeout value for an URQ transaction.

ras timeout arq ?

  <1000-45000>  Timeout value in milliseconds - default: 5000 

ras timeout arq 1000 

ras timeout brq 1000 

ras timeout drq 1000

ras timeout grq 1000

ras timeout rrq 1000

ras timeout urq 1000

Additional References

The following sections provide references related to configuring H.323 support.

Related Documents

Related Topic	Document Title
Cisco IOS XR master command reference	Cisco IOS XR Master Commands List
Cisco IOS XR SBC interface configuration commands	Cisco IOS XR Session Border Controller Command Reference
Initial system bootup and configuration information for a router using the Cisco IOS XR Software	Cisco IOS XR Getting Started Guide
Cisco IOS XR command modes	Cisco IOS XR Command Mode Reference

Standards

Standards	Title
No new or modified standards are supported by this feature, and support from existing standards has not been modified by this feature.	—

MIBs

MIBs	MIBs Link
—	To locate and download MIBs using Cisco IOS XR software, use the Cisco MIB Locator found at the following URL and choose a platform under the Cisco Access Products menu: http://cisco.com/public/sw-center/netmgmt/cmtk/mibs.shtml

RFCs

RFCs	Title
RFC 2833	RTP Payload for DTMF Digits, Telephony Tones and Telephony Signals

Technical Assistance

Description	Link
The Cisco Technical Support website contains thousands of pages of searchable technical content, including links to products, technologies, solutions, technical tips, and tools. Registered Cisco.com users can log in from this page to access even more content.	http://www.cisco.com/techsupport