Troubleshooting Intracluster Cisco Unified IP Phone Calls
The case study in this section discusses in detail the call flow between two Cisco Unified IP Phones within a cluster, called an intracluster call. This case study also focuses on Unified Communications Manager and Cisco Unified IP Phone initialization, registration, and keepalive processes. A detailed explanation of an intracluster call flow follows the discussion.
You have two clusters that are named Cluster 1 and Cluster 2; the two Unified Communications Managers in Cluster 1 are called Unified CM3 and Unified CM4, while the two Unified Communications Managers in Cluster 2 are called Unified CM1 and Unified CM2.
The traces that are collected for this case study come from Unified CM1, which is located in Cluster 2, as shown in the following figure. The two Cisco Unified IP Phones in Cluster 2 provide the basis for the call flow. The IP addresses of these two Cisco Unified IP Phones specify 172.16.70.230 (directory number 1000) and 172.16.70.231 (directory number 1001), respectively.
Cisco Unified IP Phone Initialization Process
The following procedure explains in detail the Cisco Unified IP Phone initialization (or boot up) process.
If you have set the appropriate options in DHCP server (such as Option 066 or Option 150), the Cisco Unified IP Phone sends a request at initialization to the DHCP server to get an IP address, Domain Name System (DNS) server address, and TFTP server name or address. It also gets a default gateway address if you have set these options in the DHCP server (Option 003).
If DHCP sends a DNS name of the TFTP sever, you need a DNS server IP address to map the name to an IP address. Bypass this step if the DHCP server sends the IP address of the TFTP server. In this case study, the DHCP server sent the IP address of TFTP because DNS was not configured.
If the DHCP reply does not include a TFTP server name, the Cisco Unified IP Phone uses the default server name.
The configuration file (.cnf) gets retrieved from the TFTP server. All .cnf files have the name SEP<mac_address>.cnf. If this is the first time that the phone is registering with the Unified Communications Manager, a default file, SEPdefault.cnf, gets downloaded to the Cisco Unified IP Phone. In this case study, the first Cisco Unified IP Phone uses the IP address 172.16.70.230 (its MAC address is SEP0010EB001720), and the second Cisco Unified IP Phone uses the IP address 172.16.70.231 (its MAC address is SEP003094C26105).
All .cnf files include the IP address(es) for the primary and secondary Unified Communications Manager(s). The Cisco Unified IP Phone uses this IP address to contact the primary Unified Communications Manager and to register.
After the Cisco Unified IP Phone connects and registers with Unified Communications Manager, the Unified Communications Manager tells the Cisco Unified IP Phone which executable version (called a load ID) to run. If the specified version does not match the executing version on the Cisco Unified IP Phone, the Cisco Unified IP Phone will request the new executable from the TFTP server and reset automatically.
Cisco Unified Communications Manager Initialization Process
This section explains the initialization process of Unified Communications Manager with the help of traces that are captured from Unified CM1 (identified by the IP address 172.16.70.228). As described previously, SDI traces provide a very effective troubleshooting tool because they detail every packet that is sent between endpoints.
This section describes the events that occur when Unified Communications Manager is initialized. Understanding how to read traces will help you to properly troubleshoot the various Unified Communications Manager processes and the effect of those processes on services such as conferencing and call forwarding.
The following messages from the Unified Communications Manager SDI trace utility show the initialization process on one of the Unified Communications Managers, in this case, Unified CM1.
The first message indicates that Unified Communications Manager started its initialization process.
The second message indicates that Unified Communications Manager read the default database values (for this case, it is the primary or publisher database).
The third message indicates Unified Communications Manager received the various messages on TCP port 8002.
The fourth message shows that, after receiving to these messages, Unified Communications Manager added a second Unified Communications Manager to its list: Unified CM2 (172.16.70.229).
The fifth message indicates that Unified Communications Manager has started and is running Unified Communications Manager version 3.1(1).
16:02:47.765 CCM|CMProcMon - Communications ManagerState Changed - Initialization Started.16:02:47.796 CCM|NodeId: 0, EventId: 107 EventClass: 3 EventInfo: Cisco CCMDatabase Defaults Read 16:02:49.937 CCM| SDL Info - NodeId: , Listen IP/Hostname: [172.16.70.228], Listen Port:  16:02:49.984 CCM|dBProcs - Adding SdlLink to NodeId: , IP/Hostname: [172.16.70.229] 16:02:51.031 CCM|NodeId: 1, EventId: 1 EventClass: 3 EventInfo: Cisco CallManager Version=<3.1(1)> started
After Unified Communications Manager is up and running, it starts several other processes within itself. Some of these processes follow, including MulticastPoint Manager, UnicastBridge Manager, digit analysis, and route list. You will find that the messages that are described during these processes are very useful when you are troubleshooting a problem that is related to the features in Unified Communications Manager.
For example, assume that the route lists are not functioning and are unusable. To troubleshoot this problem, you would monitor these traces to determine whether the Unified Communications Manager started RoutePlanManager and if it is trying to load the RouteLists. The following sample configuration shows that RouteListName="ipwan" and RouteGroupName="ipwan" are loading and starting.
16:02:51.031 CCM|MulicastPointManager - Started16:02:51.031 CCM|UnicastBridgeManager - Started 16:02:51.031 CCM|MediaTerminationPointManager - Started 16:02:51.125 CCM|MediaCoordinator(1) - started 16:02:51.125 CCM|NodeId: 1, EventId: 1543 EventClass: 2 EventInfo: Database manager started 16:02:51.234 CCM|NodeId: 1, EventId: 1542 EventClass: 2 EventInfo: Link manager started 16:02:51.390 CCM|NodeId: 1, EventId: 1541 EventClass: 2 EventInfo: Digit analysis started 16:02:51.406 CCM|RoutePlanManager - Started, loading RouteLists 16:02:51.562 CCM|RoutePlanManager - finished loading RouteLists 16:02:51.671 CCM|RoutePlanManager - finished loading RouteGroups 16:02:51.671 CCM|RoutePlanManager - Displaying Resulting RoutePlan 16:02:51.671 CCM|RoutePlanServer - RouteList Info, by RouteList and RouteGroup Selection Order 16:02:51.671 CCM|RouteList - RouteListName="ipwan" 16:02:51.671 CCM|RouteList - RouteGroupName="ipwan" 16:02:51.671 CCM|RoutePlanServer - RouteGroup Info, by RouteGroup and Device Selection Order 16:02:51.671 CCM|RouteGroup - RouteGroupName="ipwan"
The following trace shows the RouteGroup that is adding the device 172.16.70.245, which is Unified CM3 that is located in Cluster 1 and is considered an H.323 device. In this case, the RouteGroup gets created to route calls to Unified CM3 in Cluster 1 with Cisco IOS Gatekeeper permission. If a problem occurs while the call is being routed to a Cisco Unified IP Phone that is located in Cluster 1, the following messages would help you find the cause of the problem.
16:02:51.671 CCM|RouteGroup - DeviceName="172.16.70.245"16:02:51.671 CCM|RouteGroup -AllPorts
Part of the initialization process shows that Unified Communications Manager is adding "Dns" (Directory Numbers). By reviewing these messages, you can determine whether the Unified Communications Manager read the directory number from the database.
16:02:51.671 CCM|NodeId: 1, EventId: 1540 EventClass: 2 EventInfo: Call control started16:02:51.843 CCM|ProcessDb - Dn = 2XXX, Line = 0, Display = , RouteThisPattern, NetworkLocation = OffNet, DigitDiscardingInstruction = 1, WhereClause = 16:02:51.859 CCM|Digit analysis: Add local pattern 2XXX , PID: 1,80,1 16:02:51.859 CCM|ForwardManager - Started 16:02:51.984 CCM|CallParkManager - Started 16:02:52.046 CCM|ConferenceManager - Started
In the following traces, the Device Manager in Unified Communications Manager statically initializes two devices. The device with IP address 172.17.70.226 represents a gatekeeper, and the device with IP address 172.17.70.245 gets another Unified Communications Manager in a different cluster. That Unified Communications Manager gets registered as an H.323 Gateway with this Unified Communications Manager.
16:02:52.250 CCM|DeviceManager: Statically Initializing Device; DeviceName=172.16.70.22616:02:52.250 CCM|DeviceManager: Statically Initializing Device; DeviceName=172.16.70.245
Cisco Unified Communications Manager Registration Process
Another important part of the SDI trace involves the registration process. When a device is powered up, it gets information using DHCP, connects to the TFTP server for its .cnf file, and then connects to the Unified Communications Manager that is specified in the .cnf file. The device could be an MGCP gateway, a Skinny gateway, or a Cisco Unified IP Phone. Therefore, you need to be able to discover whether devices successfully registered on the Cisco network.
In the following trace, Unified Communications Manager received new connections for registration. The registering devices comprise MTP_nsa-cm1 (MTP services on Unified CM1) and CFB_nsa-cm1 (Conference Bridge service on Unified CM1). Although these are software services that are running on Unified Communications Manager, they get treated internally as different external services and therefore get assigned a TCPHandle, socket number, and port number as well as a device name.
16:02:52.750 CCM|StationInit - New connection accepted. DeviceName=, TCPHandle=0x4fbaa00, Socket=0x594, IPAddr=172.16.70.228, Port=3279, StationD=[0,0,0]16:02:52.750 CCM|StationInit - New connection accepted. DeviceName=, TCPHandle=0x4fe05e8, Socket=0x59c, IPAddr=172.16.70.228, Port=3280, StationD=[0,0,0] 16:02:52.781 CCM|StationInit - Processing StationReg. regCount: 1 DeviceName=MTP_nsa-cm1, TCPHandle=0x4fbaa00, Socket=0x594, IPAddr=172.16.70.228, Port=3279, StationD=[1,45,2] 16:02:52.781 CCM|StationInit - Processing StationReg. regCount: 1 DeviceName=CFB_nsa-cm1, TCPHandle=0x4fe05e8, Socket=0x59c, IPAddr=172.16.70.228, Port=3280, StationD=[1,96,2]
Cisco Unified Communications Manager KeepAlive Process
The station, device, or service and the Unified Communications Manager use the following messages to maintain a knowledge of the communications channel between them. The messages begin the keepalive sequence that ensures that the communications link between the Unified Communications Manager and the station remains active. The following messages can originate from either the Unified Communications Manager or the station.
16:03:02.328 CCM|StationInit - InboundStim - KeepAliveMessage - Forward KeepAlive to StationD. DeviceName=MTP_nsa-cm2, TCPHandle=0x4fa7dc0, Socket=0x568, IPAddr=172.16.70.229, Port=1556, StationD=[1,45,1]16:03:02.328 CCM|StationInit - InboundStim - KeepAliveMessage - Forward KeepAlive to StationD. DeviceName=CFB_nsa-cm2, TCPHandle=0x4bf8a70, Socket=0x57c, IPAddr=172.16.70.229, Port=1557, StationD=[1,96,1] 16:03:06.640 CCM|StationInit - InboundStim - KeepAliveMessage - Forward KeepAlive to StationD. DeviceName=SEP0010EB001720, TCPHandle=0x4fbb150, Socket=0x600, IPAddr=172.16.70.230, Port=49211, StationD=[1,85,2] 16:03:06.703 CCM|StationInit - InboundStim - KeepAliveMessage - Forward KeepAlive to StationD. DeviceName=SEP003094C26105, TCPHandle=0x4fbbc30, Socket=0x5a4, IPAddr=172.16.70.231, Port=52095, StationD=[1,85,1]
The messages in the following trace depict the keepalive sequence that indicates that the communications link between the Unified Communications Manager and the station is active. Again, these messages can originate from either the Unified Communications Manager or the station.
16:03:02.328 CCM|MediaTerminationPointControl - stationOutputKeepAliveAck tcpHandle=4fa7dc016:03:02.328 CCM|UnicastBridgeControl - stationOutputKeepAliveAck tcpHandle=4bf8a70 16:03:06.703 CCM|StationInit - InboundStim - IpPortMessageID: 32715(0x7fcb) tcpHandle=0x4fbbc30 16:03:06.703 CCM|StationD - stationOutputKeepAliveAck tcpHandle=0x4fbbc30
Cisco Unified Communications Manager Intracluster Call Flow Traces
The following SDI traces explore the intracluster call flow in detail. You can identify Cisco Unified IP Phones in the call flow by the directory number (dn), tcpHandle, and IP address. A Cisco Unified IP Phone (dn: 1001, tcpHandle: 0x4fbbc30, IP address: 172.16.70.231) that is located in Cluster 2 calls another Cisco Unified IP Phone in the same cluster (dn=1000, tcpHandle= 0x4fbb150, IP address= 172.16.70.230). Remember that you can follow a device through the trace by looking at the TCP handle value, time stamp, or name of the device. The TCP handle value for the device remains the same until the device is rebooted or goes offline.
The following traces show that the Cisco Unified IP Phone (1001) has gone off hook. The following trace shows the unique messages, TCP handle, and the called number, which display on the Cisco Unified IP Phone. No calling number displays at this point because the user has not tried to dial any digits. The following information displays in the form of Skinny Station messages between the Cisco Unified IP Phones and the Unified Communications Manager.
16:05:41.625 CCM|StationInit - InboundStim - OffHookMessageID tcpHandle=0x4fbbc3016:05:41.625 CCM|StationD - stationOutputDisplayText tcpHandle=0x4fbbc30, Display= 1001
The next trace shows Skinny Station messages that go from Unified Communications Manager to a Cisco Unified IP Phone. The first message turns on the lamp on the calling party Cisco Unified IP Phone.
16:05:41.625 CCM|StationD - stationOutputSetLamp stim: 9=Line instance=1 lampMode=LampOn tcpHandle=0x4fbbc30
Unified Communications Manager uses the stationOutputCallState message to notify the station of certain call-related information.
16:05:41.625 CCM|StationD - stationOutputCallState tcpHandle=0x4fbbc30
Unified Communications Manager uses the stationOutputDisplayPromptStatus message to cause a call-related prompt message to display on the Cisco Unified IP Phone.
16:05:41.625 CCM|StationD - stationOutputDisplayPromptStatus tcpHandle=0x4fbbc30
Unified Communications Manager uses the stationOutputSelectSoftKey message to cause the Skinny Station to choose a specific set of soft keys.
16:05:41.625 CCM|StationD - stationOutputSelectSoftKeys tcpHandle=0x4fbbc30
Unified Communications Manager uses the next message to instruct the Skinny Station about the correct line context for the display.
16:05:41.625 CCM|StationD - stationOutputActivateCallPlane tcpHandle=0x4fbbc30
The following message indicates that the digit analysis process is ready to identify incoming digits and check them for potential routing matches in the database. The entry, cn=1001, represents the calling party number where dd="" represents the dialed digit, which would show the called party number. The phone sends StationInit messages, Unified Communications Manager sends StationD messages, and Unified Communications Manager performs digit analysis.
16:05:41.625 CCM|Digit analysis: match(fqcn="", cn="1001", pss="", dd="")16:05:41.625 CCM|Digit analysis: potentialMatches=PotentialMatchesExist
The following debug message shows that the Unified Communications Manager is providing inside dial tone to the calling party Cisco Unified IP Phone.
16:05:41.625 CCM|StationD - stationOutputStartTone: 33=InsideDialTone tcpHandle=0x4fbbc30
After Unified Communications Manager detects an incoming message and recognizes that the keypad button 1 has been pressed on the Cisco Unified IP Phone, it immediately stops the output tone.
16:05:42.890 CCM|StationInit - InboundStim - KeypadButtonMessageID kpButton: 1 tcpHandle=0x4fbbc3016:05:42.890 CCM|StationD - stationOutputStopTone tcpHandle=0x4fbbc30 16:05:42.890 CCM|StationD - stationOutputSelectSoftKeys tcpHandle=0x4fbbc30 16:05:42.890 CCM|Digit analysis: match(fqcn="", cn="1001", pss="", dd="1") 16:05:42.890 CCM|Digit analysis: potentialMatches=PotentialMatchesExist 16:05:43.203 CCM|StationInit - InboundStim - KeypadButtonMessageID kpButton: 0 tcpHandle=0x4fbbc30 16:05:43.203 CCM|Digit analysis: match(fqcn="", cn="1001", pss="", dd="10") 16:05:43.203 CCM|Digit analysis: potentialMatches=PotentialMatchesExist 16:05:43.406 CCM|StationInit - InboundStim - KeypadButtonMessageID kpButton: 0 tcpHandle=0x4fbbc30 16:05:43.406 CCM|Digit analysis: match(fqcn="", cn="1001", pss="", dd="100") 16:05:43.406 CCM|Digit analysis: potentialMatches=PotentialMatchesExist 16:05:43.562 CCM|StationInit - InboundStim - KeypadButtonMessageID kpButton: 0 tcpHandle=0x4fbbc30 16:05:43.562 CCM|Digit analysis: match(fqcn="", cn="1001", pss="", dd="1000")
After the Unified Communications Manager receives enough digits to match, it provides the digit analysis results in a table format. Unified Communications Manager ignores any extra digits that are pressed on the phone after this point because a match already has been found.
16:05:43.562 CCM|Digit analysis: analysis results16:05:43.562 CCM||PretransformCallingPartyNumber=1001 |CallingPartyNumber=1001 |DialingPattern=1000 |DialingRoutePatternRegularExpression=(1000) |PotentialMatches=PotentialMatchesExist |DialingSdlProcessId=(1,38,2) |PretransformDigitString=1000 |PretransformPositionalMatchList=1000 |CollectedDigits=1000 |PositionalMatchList=1000 |RouteBlockFlag=RouteThisPattern
The next trace shows that Unified Communications Manager is sending out this information to a called party phone (the tcpHandle number identifies the phone).
16:05:43.578 CCM|StationD - stationOutputCallInfo CallingPartyName=1001, CallingParty=1001, CalledPartyName=1000, CalledParty=1000, tcpHandle=0x4fbb150
The next trace indicates that Unified Communications Manager is ordering the lamp to blink for incoming call indication on the called party Cisco Unified IP Phone.
16:05:43.578 CCM|StationD - stationOutputSetLamp stim: 9=Line instance=1 lampMode=LampBlink tcpHandle=0x4fbb150
In the following traces, Unified Communications Manager provides ringer, display notification, and other call-related information to the called party Cisco Unified IP Phone. Again, you can see that all messages get directed to the same Cisco Unified IP Phone because the same tcpHandle gets used throughout the traces.
16:05:43.578 CCM|StationD - stationOutputSetRinger: 2=InsideRing tcpHandle=0x4fbb15016:05:43.578 CCM|StationD - stationOutputDisplayNotify tcpHandle=0x4fbb150 16:05:43.578 CCM|StationD - stationOutputDisplayPromptStatus tcpHandle=0x4fbb150 16:05:43.578 CCM|StationD - stationOutputSelectSoftKeys tcpHandle=0x4fbb150
Notice that Unified Communications Manager also provides similar information to the calling party Cisco Unified IP Phone. Again, the tcpHandle differentiates between Cisco Unified IP Phones.
16:05:43.578 CCM|StationD - stationOutputCallInfo CallingPartyName=1001, CallingParty=1001, CalledPartyName=, CalledParty=1000, tcpHandle=0x4fbbc3016:05:43.578 CCM|StationD - stationOutputCallInfo CallingPartyName=1001, CallingParty=1001, CalledPartyName=1000, CalledParty=1000, tcpHandle=0x4fbbc30
In the next trace, Unified Communications Manager provides an alerting or ringing tone to the calling party Cisco Unified IP Phone and provides notification that the connection has been established.
16:05:43.578 CCM|StationD - stationOutputStartTone: 36=AlertingTone tcpHandle=0x4fbbc3016:05:43.578 CCM|StationD - stationOutputCallState tcpHandle=0x4fbbc30 16:05:43.578 CCM|StationD - stationOutputSelectSoftKeys tcpHandle=0x4fbbc30 16:05:43.578 CCM|StationD - stationOutputDisplayPromptStatus tcpHandle=0x4fbbc30
At this point, the called party Cisco Unified IP Phone goes off hook; therefore, Unified Communications Manager stops generating the ringer tone to calling party.
16:05:45.140 CCM|StationD - stationOutputStopTone tcpHandle=0x4fbbc30
In the following messages, Unified Communications Manager causes the Skinny Station to begin receiving a Unicast RTP stream. To do so, Unified Communications Manager provides the IP address of the called party as well as codec information and packet size in msec (milliseconds). PacketSize designates an integer that contains the sampling time, in milliseconds, that is used to create the RTP packets.
This value normally gets set to 30 msec. In this case, it gets set to 20 msec.
16:05:45.140 CCM|StationD - stationOutputOpenReceiveChannel tcpHandle=0x4fbbc30 myIP: e74610ac (172.16.70.231)16:05:45.140 CCM|StationD - ConferenceID: 0 msecPacketSize: 20 compressionType:(4)Media_Payload_G711Ulaw64k
Similarly, Unified Communications Manager provides information to the called party (1000).
16:05:45.140 CCM|StationD - stationOutputOpenReceiveChannel tcpHandle=0x4fbb150 myIP: e64610ac (172.16.70.230)16:05:45.140 CCM|StationD - ConferenceID: 0 msecPacketSize: 20 compressionType:(4)Media_Payload_G711Ulaw64k
Unified Communications Manager received the acknowledgment message from called party for establishing the open channel for RTP stream, as well as the IP address of the called party. This message informs the Unified Communications Manager of two pieces of information about the Skinny Station. First, it contains the status of the open action. Second, it contains the receive port address and number for transmission to the remote end. The IP address of the transmitter (calling part) of the RTP stream specifies ipAddr, and PortNumber specifies the IP port number of the RTP stream transmitter (calling party).
16:05:45.265 CCM|StationInit - InboundStim - StationOpenReceiveChannelAckID tcpHandle=0x4fbb150, Status=0, IpAddr=0xe64610ac, Port=17054, PartyID=2
Unified Communications Manager uses the following messages to order the station to begin transmitting the audio and video streams to the indicated remote Cisco Unified IP Phone IP address and port number.
16:05:45.265 CCM|StationD - stationOutputStartMediaTransmission tcpHandle=0x4fbbc30 myIP: e74610ac (172.16.70.231)16:05:45.265 CCM|StationD - RemoteIpAddr: e64610ac (172.16.70.230) RemoteRtpPortNumber: 17054 msecPacketSize: 20 compressionType:(4)Media_Payload_G711Ulaw64k 16:03:25.328 CCM|StationD(1): TCPPid=[18.104.22.168] OpenMultiReceiveChannel conferenceID=16777217 passThruPartyID=1000011 compressionType=101(Media_Payload_H263) qualifierIn=?. myIP: e98e6b80 (22.214.171.124)|<CT::1,100,11,1.1><IP::><DEV::> 16:03:25.375 CCM|StationInit: TCPPid=[126.96.36.199] StationOpenMultiMediaReceiveChannelAck Status=0, IpAddr=0xe98e6b80, Port=65346, PartyID=16777233|<CT::1,100,105,1.215><IP::188.8.131.52> 16:03:25.375 CCM|StationD(2): TCPPid = [184.108.40.206] star_StationOutputStartMultiMediaTransmission conferenceID=16777218 passThruPartyID=16777250 remoteIpAddress=e98e6b80(220.127.116.11) remotePortNumber=65346 compressType=101(Media_Payload_H263) qualifierOut=?. myIP: e98e6b80 (18.104.22.168)|<CT::1,100,105,1.215><IP::22.214.171.124>
In the following traces, the previously explained messages get sent to the called party. The messages that indicate that the RTP media stream started between the called and calling party follow these messages.
16:05:45.312 CCM|StationD - stationOutputStartMediaTransmission tcpHandle=0x4fbb150 myIP: e64610ac (172.16.70.230)16:05:45.328 CCM|StationD - RemoteIpAddr: e74610ac (172.16.70.231) RemoteRtpPortNumber: 18448 msecPacketSize: 20 compressionType:(4)Media_Payload_G711Ulaw64k 16:05:46.203 CCM|StationInit - InboundStim - OnHookMessageID tcpHandle=0x4fbbc30
The calling party Cisco IP Phone finally goes on hook, which terminates all the control messages between the Skinny Station and Unified Communications Manager as well as the RTP stream between Skinny Stations.
16:05:46.203 CCM|StationInit - InboundStim - OnHookMessageID tcpHandle=0x4fbbc30