CUCM和VCS在呼叫时体验单向音频

简介

本文档介绍如何对视频通信服务器(VCS)和Cisco Unified Communications Manager(CUCM)之间呼叫的单向音频问题进行故障排除。

问题

这样的呼叫，Endpoint 1 - H323 - VCS - SIP - CUCM - Endpoint 2，可能导致终端1听不到终端2的单向音频。

以下是来自VCS的日志分析。

VCS将200 OK发送到Call Manager:

2014-01-23T12:40:10+11:00 vcs-cont-pro-1 tvcs: UTCTime="2014-01-23 01:40:10,296"
Module="network.sip" Level="DEBUG": Dst-ip="10.69.12.2" Dst-port="60493"
 SIPMSG:
 |SIP/2.0 200 OK
 Via: SIP/2.0/TCP 10.69.12.2:5060;branch=z9hG4bK2359e3e241306;received=
10.69.12.2;ingress-zone=CUCMNeighbour
 Call-ID: 8935a699d9e9e3f8@127.0.0.1
 CSeq: 102 INVITE
 Contact: <sip:AVS.EX60.-.Elliott@172.17.254.1>
 From: <sip:00419241145@10.69.11.1:5060>;tag=6417ce1c-8b93-4ba0-859a-ad892a39
e373-92748854
 To: <sip:AVS.EX60.-.Elliott@172.17.254.1>;tag=27b6f95b717b59fc
v=0
 o=tandberg 0 3 IN IP4 127.0.0.1
 s=-
 c=IN IP4 172.17.254.1
 b=AS:512
 t=0 0
 m=audio 51390 RTP/AVP 0 101
 b=TIAS:64000
 a=rtpmap:0 PCMU/8000
 a=rtpmap:101 telephone-event/8000
 a=fmtp:101 0-15
 a=sendrecv
 a=rtcp:51391 IN IP4 172.17.254.1

在MasterSlaveDetermination之前，VCS尝试向终端发送OpenLogicalChannel(OLC)，这会导致终端拒绝OLC:

2014-01-23T12:40:10+11:00 vcs-cont-pro-1 tvcs: UTCTime="2014-01-23 01:40:10,366"
Module="network.h323" Level="DEBUG": Dst-ip="172.19.83.180" Dst-port="11158"
 Sending H.245 PDU:
 value MultimediaSystemControlMessage ::= request : openLogicalChannel :
 {
 forwardLogicalChannelNumber 1,
 forwardLogicalChannelParameters
 {
 dataType audioData : g711Ulaw64k : 40,
 multiplexParameters h2250LogicalChannelParameters :
 {
 sessionID 1,
 mediaControlChannel unicastAddress : iPAddress :
 {
 network 'AC11FE01'H,
 tsapIdentifier 51669
 },
 transportCapability
 {
 mediaChannelCapabilities
 {
{
 mediaTransport ip-UDP : NULL
 }
 }
 }
 }
 }
 }

以下是来自终端的MasterSlaveDetermination:

2014-01-23T12:40:10+11:00 vcs-cont-pro-1 tvcs: UTCTime="2014-01-23 01:40:10,475"
Module="network.h323" Level="INFO": Src-ip="172.19.83.180" Src-port="11158"
 Detail="Received H.245 MasterSlaveDeterminationRequest "
2014-01-23T12:40:10+11:00 vcs-cont-pro-1 tvcs: UTCTime="2014-01-23 01:40:10,475"
Module="network.h323" Level="DEBUG": Src-ip="172.19.83.180" Src-port="11158"
 Received H.245 PDU:
 value MultimediaSystemControlMessage ::= request : masterSlaveDetermination :
 {
 terminalType 190,
 statusDeterminationNumber 8028716
 }

以下是终端的MasterSlaveDeterminationAck:

2014-01-23T12:40:10+11:00 vcs-cont-pro-1 tvcs: UTCTime="2014-01-23 01:40:10,475"
Module="network.h323" Level="INFO": Dst-ip="172.19.83.180" Dst-port="11158"
 Detail="Sending H.245 MasterSlaveDeterminationAckResponse Master"
2014-01-23T12:40:10+11:00 vcs-cont-pro-1 tvcs: UTCTime="2014-01-23 01:40:10,475"
Module="network.h323" Level="DEBUG": Dst-ip="172.19.83.180" Dst-port="11158"
 Sending H.245 PDU:
 value MultimediaSystemControlMessage ::= response : masterSlaveDeterminationAck :
 {
 decision master : NULL
 }

终端拒绝OLC会导致单向音频，因为OLC在MasterSlaveDetermination之前进入。

2014-01-23T12:40:10+11:00 vcs-cont-pro-1 tvcs: UTCTime="2014-01-23 01:40:10,519"
Module="network.h323" Level="INFO": Src-ip="172.19.83.180" Src-port="11158"
 Detail="Received H.245 OpenLogicalChannelRejResponse "
2014-01-23T12:40:10+11:00 vcs-cont-pro-1 tvcs: UTCTime="2014-01-23 01:40:10,519"
Module="network.h323" Level="DEBUG": Src-ip="172.19.83.180" Src-port="11158"
 Received H.245 PDU:
 value MultimediaSystemControlMessage ::= response : openLogicalChannelReject :
 {
 forwardLogicalChannelNumber 1,
 cause masterSlaveConflict : NULL
 }

解决方案

此问题是由Cisco Bug ID CSCuc98144 引起的，解决方法是在CUCM区域的VCS区域配置文件上关闭允许空INVITE。这会强制VCS发送带预配置会话描述协议(SDP)的初始INVITE，该协议允许呼叫在两个方向上与音频连接。

在VCS Configuration -> Zones -> Zones下，选择CUCM区域，并更改此屏幕截图中指示的字段：

另一个选项是将VCS升级到X8.1.1版，解决了问题。

注意：这只是呼叫可能具有单向音频的原因之一。