05 H323速成 - 图文(8)

H323和SIP协议快速入门手册

network: XUHAO_TEST (172.16.195.246) tsapIdentifier: 30037

h245Tunneling: True

H245 Tunneling

H245 Tunneling 是我自己定义的一个名称，并不是说它是一个命令。因为在快速呼叫建立过程中，没有H245的包，H245的控制信令都是通过H225信令中的Facility消息体以隧道方式来传送的。下面将列举H245控制命令是如何通过H225隧道来发送的。其传输方式可以看命令18、19、21—32。

9. Q.931

Protocol discriminator: Q.931 Call reference value length: 2 Call reference value: 0A80 Message type: FACILITY (0x62) Facility

Information element: Facility Length: 0 Data:

ITU-T Recommendation H.225.0 h323_uu_pdu (H323-UU-PDU) h323_message_body (empty) empty: empty h245Tunneling: True

h245Control 0: TerminalCapabilitySet

10.Q.931

Protocol discriminator: Q.931 Call reference value length: 2 Call reference value: 0A80 Message type: FACILITY (0x62) Facility

Information element: Facility ITU-T Recommendation H.225.0 h323_uu_pdu (H323-UU-PDU) h323_message_body (empty) empty: empty h245Tunneling: True

h245Control 0: MasterSlaveDetermination request

masterSlaveDetermination

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H323和SIP协议快速入门手册

terminalType: 50

statusDeterminationNumber: 15345728

11.Q.931

Message type: FACILITY (0x62) Facility

Information element: Facility h323_uu_pdu (H323-UU-PDU) h323_message_body (empty) empty: empty h245Tunneling: True

h245Control 0: MasterSlaveDeterminationAck response

masterSlaveDeterminationAck decision (master) master: master

12.Q.931

Message type: FACILITY (0x62) Facility

Information element: Facility ITU-T Recommendation H.225.0 h323_uu_pdu (H323-UU-PDU) h323_message_body (empty) empty: empty h245Tunneling: True

h245Control 0: TerminalCapabilitySetAck response

terminalCapabilitySetAck sequenceNumber: 1

DRQ/DCF/ReleaseComplete

DRQ/DCF/ReleaseComplete命令是H225信令里的关于呼叫释放的命令。在正常的拆线过程中，一般的顺序为先挂机的一方：关闭H245逻辑控制信道、结束H245会话、通过DRQ/DCF命令请求脱离会话，再用ReleaseComplete释放H225信道；后挂机的一方：收到系统的结束H245会话、ReleaseComplete释放H225信道命令后，向系统发出关闭H245逻辑控制信道、结束H245会话和DRQ请求脱离会话命令来关闭所有的连接。看命令33—46。 具体的包如下：

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H323和SIP协议快速入门手册

13.Q.931

Message type: FACILITY (0x62) Facility

Information element: Facility h323_uu_pdu (H323-UU-PDU) h323_message_body (empty) empty: empty h245Tunneling: True

h245Control 0: CloseLogicalChannel

14.Q.931

Message type: FACILITY (0x62) Facility

Information element: Facility h323_message_body (empty) empty: empty h245Tunneling: True

h245Control 0: CloseLogicalChannelAck response

closeLogicalChannelAck

forwardLogicalChannelNumber: 1

15.Q.931

Message type: FACILITY (0x62) Facility

Information element: Facility ITU-T Recommendation H.225.0 h323_uu_pdu (H323-UU-PDU) h323_message_body (empty) empty: empty h245Tunneling: True

h245Control 0: EndSessionCommand command

endSessionCommand

disconnect: disconnect

16.ITU-T Recommendation H.225.0

disengageRequest

requestSeqNum: 24555

endpointIdentifier: F6C310AC9AC310AC40A2EB41HCFFCBPM conferenceID: 02134FBC-5269-1CF8-5634-343434EF0000 callReferenceValue: 28370

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H323和SIP协议快速入门手册

disengageReason (normalDrop) normalDrop: normalDrop callIdentifier (CallIdentifier)

guid: 02134FBC-5267-6AF4-5634-343434EF0000 gatekeeperIdentifier: 1000 answeredCall: False

17.ITU-T Recommendation H.225.0

disengageConfirm

requestSeqNum: 24555

18.Q.931

Message type: RELEASE COMPLETE (0x5a) Cause

Information element: Cause ITU-T Recommendation H.225.0 h323_uu_pdu (H323-UU-PDU)

h323_message_body (releaseComplete) releaseComplete

protocolIdentifier: 0.0.8.2250.0.3 reason (undefinedReason)

undefinedReason: undefinedReason callIdentifier (CallIdentifier)

guid: 02134FBC-5267-6AF4-5634-343434EF0000 h245Tunneling: True

到此所有呼叫信令结束，主被叫挂机，信令流程走完。

SIP协议介绍

SIP概述

SIP是Internet工程任务组（IETF）提出的建议中的一项协议，其目的是为了替代H.323的部分协议。由于H.323是一个协议集，因此SIP是几个共同完成呼叫任务的服务协议中的一个协议。

SIP是一种应用层控制与信令协议，用于创建、修改和结束与一个或多个参与者的会话。这些会话可以包括Internet多媒体会议、远程学习、Internet电话呼叫以及多媒体发布。SIP可以邀请人以及诸如媒体存储服务这类“机器人”来参与一次呼叫。

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