Microsoft Lync Server 2013 : Mediation Server Troubleshooting (part 2) - Synthetic Transactions, Telnet

5. Lync Server Management Shell

The Lync Server 2013 Management Shell provides several cmdlets that can be used to test various functions of a server. A useful cmdlet for verifying the overall health of a server is Test-CSComputer which verifies that all services are running, that the local computer group membership is correctly populated with the necessary Lync Server Active Mediation Server groups, and that the required Windows Firewall ports have been opened. The Test-CSComputer cmdlet must be run from the local computer and it uses the following syntax:

Test-CSComputer -Report "C:\Test-CSComputer Results.xml"

After running the cmdlet, open the generated XML file to view a detailed analysis of each check.

6. Synthetic Transactions

A feature carried over from Lync Server 2010 is synthetic transactions, which are a set of PowerShell cmdlets used to simulate actions taken by servers or users in the environment. These synthetic transactions allow an administrator to conduct realistic tests against a service. In the case of a Mediation Server, the two most useful synthetic transactions are Test-CSOutboundCall and Test-CSPSTNPeertoPeerCall.

When Test-CSOutboundCall is run, a full outbound call is made to a phone number the administrator provides. This transaction tests the policies, and signaling and media connectivity to the PSTN. After the signaling path has been established, the transaction sends DTMF tones to validate media connectivity. Running this cmdlet requires a user account to authenticate and register to Lync Server 2013, as well as a valid destination phone number. The user credential parameter’s username and password must be collected by an authentication dialog and saved to a variable, as seen in this command:

$Credential = Get-Credential "COMPANYABC\randy"

After the credentials have been collected, the cmdlet can be run with the user credential variable previously saved:

Test-CsPstnOutboundCall -TargetFqdn <Front End Pool FQDN> -TargetPstnPhoneNumber "+15551234567" -UserSipAddress "sip:[email protected]" -UserCredential $credential

Here’s a Test-CSPSTNOutboundCall example:

TargetFQDN     : Lyncpool1.companyabc.com
Result         : Success
Latency       : 00:00:10.9506726

As seen in the output, the call was successful.

Test-CSPSTNPeertoPeerCall is very similar; however, it establishes a call between two Lync users over the PSTN. This transaction logs in two Lync users, dials through the PSTN gateway, and routes back in to Lync Server to connect to the second user. The call is established, and then terminates on its own after media connectivity has been validated. To run this cmdlet, you must provide two valid user accounts in Lync Server 2013. See the following text for an example.

The user credential parameter’s username and password must be collected by an authentication dialog and saved to a variable, as seen in the following command:

$Credential1 = Get-Credential "COMPANYABC\randy"
$Credential2 = Get-Credential "COMPANYABC\alex"

Test-CsPstnPeerToPeerCall -TargetFqdn <FRONT END POOL FQDN> -SenderSipAddress "sip:[email protected]" -SenderCredential $credential1 -ReceiverSipAddress "sip:[email protected]" -ReceiverCredential $credential2

Here’s a Test-CSPSTNPSTNPeertoPeerCall example:

TargetFQDN     : Lyncpool1.companyabc.com
Result         : Success
Latency        : 00:00:10.9506726

As seen in the output, the call was successful.

7. Telnet

Telnet is a simple method of checking whether a specific TCP port is available from a client machine. From a machine that is having trouble contacting a Mediation Server, follow these steps to verify connectivity to the Mediation Server service:

1. Open a command prompt.

2. Type the following command:

telnet <Mediation Server pool FQDN> 5061

If the window goes blank and only a flashing cursor is seen, it means the connection was successful and the port can be contacted without issue. If the connection fails, an error is returned. Check that the services are running on the Mediation Server and that no firewalls are blocking the traffic.

8. Time

A key component of any service running successfully in Lync Server 2013 is the computer time. Be sure to verify that the clocks on any Lync Server 2013 servers are correctly set and have the appropriate time zones configured. If the clocks between a server and a client are off by more than five minutes, Kerberos authentication will begin to fail, which will prevent users from authenticating successfully.