DEFINITY Enterprise Communications Server Release 7
Maintenance for R7r
555-230-126
Issue 4
June 1999
Alarms, Errors, and Troubleshooting
5-66Troubleshooting ISDN-PRI Problems
5
When a downgrade does occur, information on the Status Conference form
indicates the success or failure of the 64kbps-endpoints that are participants to
properly rate adapt to 56kbps. As a general indication that the conference has
rate adapted, the Conference Transfer Rate and Effective Transfer
Rate fields show initial and current transfer rates, respectively. For each 64-kbps
endpoint the column that indicates Rate Adapt shows an n if the endpoint did
not follow the procedures as specified by the H.221. If an endpoint shows y, it did
successfully rate adapt. If an endpoint shows c, it joined the conference at
56kbps.
Once the conference rate adapts, the endpoints that do not properly follow suit,
will become audio-only endpoints. A conference will not rate adapt from 56 kbps
back to 64 kbps until all endpoints disconnect from the conference and it idles.
The PictureTel 1000 Release 1.1C, PictureTel 6.01 software, and the Vistium 2.0
software successfully rate adapt with the MCU. External rate adaptation
techniques used by VTEL and CLI are known to cause problems with the
endpoint when used with this feature.
Endpoint or I-MUX in Loopback Mode
Some endpoints have a loopback enable feature. This makes DEFINITY MMCH
data loopback at the MMCH when a connection is in progress. The loopback can
be enabled prior to or during a connection.
The MMCH does not detect the loop and continues to VAS. In most scenarios,
the switch occurs, but within a few seconds, the broadcaster’s return video
becomes its own image. Once the broadcaster stops speaking, the system
“false” switches to an apparently random port that was not speaking.
Troubleshooting ISDN-PRI Problems
The following flow chart defines a layered approach when troubleshooting
ISDN-PRI problems. Since a problem at a lower layer affects upper layers, layers
are investigated from low to high. In the flowchart, the DS1 facility is layer 1, the
ISDN-PRI D-channel is layer 2, and the ISDN trunks are layer 3. Transient
problems are diagnosed on Page 2 of the flowchart. For problems with PRI
endpoints (wideband), see the following section.
