DEFINITY Enterprise Communications Server Release 7
Maintenance for R7r
555-230-126 Issue 4
June 1999
Alarms, Errors, and Troubleshooting
5-62Multimedia Call Handling (MMCH)
5
Calls Terminate with No Video
Description
Generally, loss of video can be divid ed into 2 types. The first occ urs when the
DEFINITY MMCH switches to the endpoint, but nobod y sees them. The receivers
see either “black” video or a frozen image of the p revious speaker dependin g on
the codec of the manufac turer. The type occurs when the DEFINITY MMCH does
not switch to an endpoint.
Solution
In the first type describ ed above, wiring prob lems, power to the camera, or video
encoder circuit pack problems in the c odec are typical c auses.
In the second type, no vid eo from an endpoint typic ally occurs because it i s not a
valid video source. This c an be checked b y looking at page 1 of the Status
Conference x Endpoint y Vid form und er the Capability section. In this sec tion, a
“y” or “c” suggests that the endp oint has video. An “e” me ans ept has not
declared any vid eo capability in cap set, “n” is audio only, and “ blank” means
audio add-on.
Also check pag e 1 of the Status Conference x Endpoint y Vs form for indication of
the video state for the endp oint values.
Calls Terminate Correctly but Are Unstable
A number of conditions wil l lead to some or all endpoints having stability
problems during the course of a conference. A lac k of stability from an endpoint
is noticeable by a lac k of a video switching while the party is the only talker or
excessive disconnec ts from that endpoint.
Synchronization
Generally, the most common problem is a mismatc h in synchronization sources
between the endpoint and the DEFINITY MMCH. This typically causes low-level
(Px64) handshake problems that ca n trigger the endpoint/MMCH to disconnect
the call. The MCCH’s timers are set to sufficiently high values so that, normally,
the endpoint will timeout and disconnect first. If installed in a customer network, it
is a good idea to p erform an audit of the path synchronization is being supplied .
If there are different clock sources between end points and the DEFINITY MMCH,
some problems are sure to occ ur. The severity of these problems can range from
a handshake failure every few second s to one per day. Depending on the type of
endpoint, this can c ause the endpoint to disc onnect or just freeze video until the
main problem is resolved.
Specifically, PictureTel System 4000 endpoints seem to be the most sensitive to
instability. The Lucent Technologies Vistium also disconnects fa irly infrequently.
Last, the CLI Rembrandt II VP freezes video and waits for framing to be
recovered .