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。