Troubleshooting guide

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Cisco Broadband Local Integrated Services Solution Troubleshooting Guide
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Chapter 9 Troubleshooting Cisco Media Gateways
Media Gateway Errors
a long time to automatically logout an idle telnet session and the telnet session is left unattended for
unauthorized personel to access the system. It is therefore recommended that the timeout value be
restored to its original value.
The mscpPrtOn command turns debugging on for Protocol layer messages prints. It takes a single
parameter value (2,3 or 4) which scales the amount of debug info to print. The number 2 will display the
least amount of debug and the number 4 will display the most. Use the following command to receive
the minimum debug information:
mscpPrtOn 2
Use the following command to receive the maximum debug information:
mscpPrtOn 4
The debug trace command prtOn takes a single parameter that specifies which software element to trace.
Trace debugging can be turned off by entering the command mscpPrtOff and prtOff. Printing to the
terminal can be prevented by entering ttyredir 0. However, Cisco strongly recommends that the
mscpPrtOff/PrtOff commands be used to turn off trace debugging because, once the trace debugging
is turned on and even though the trace output is not directed to the terminal, system performance is still
drastically slowed down .
Media Gateway Errors
Use the lsndinf command to verify that the MGX8850 is set up in MGCP protocol. If not, then use the
chprotocol command to change it to MGCP. MGCP is a standard protocol defined by the Internet
Engineering Task Force (IETF). MGCP supports TDM, Vo I P, a n d Vo AT M . N o t e t h a t Vo I P a n d Vo AT M
are mutually exclusive.
Once the MGX8850 is running in MGCP protocol mode, the MGCP specific parameters need to be
configured. Configuring these parameters makes it possible for the MGX8850 to communicate with its
corresponding Call Agent.
Before making any changes to the MGCP protocol parameters, it is best to see how the switch is already
configured. Use the commands lsmgcp and msmgcpdef to display the current MGCP parameter values.
System Redundancy
SCC, NSC, and BSC are three types of cards that support redundancy. SCC and BSC support 1:1
redundancy and NSC supports n:1 redundancy.
SCC Redundancy
SCC redundancy need not be configured. Each MGX8260 can have upto 2 SCCs, on only slots 9 and 10.
When both SCCs are present, one goes to Active state while the other goes to Standby state, based on
several criteria.
The Active SCC provides all the system functionality until there is a failure or a reset or if that card is
removed from the MGX8260. When that happens, if there is a Standby SCC, the Standby SCC becomes
active and provides the system functionality. Active calls are not dropped, however they might
experience a loss of voice for a fraction of a second. Some of the new calls may get dropped during this
switchover. The newly-active SCC becomes available within a few seconds.