about isdn pri call signalling / down speeding on vsx 7000

[ROYAL]

HAiiiiiiiii GUYS.............


I just want to know how the isdn pri call signalling will work on multipoint with 30 channels.
for example:-
if iam in point to point call on isdn with pri on 256kbps.means first four channels are occupied .when i made 2nd call at 256 kbps how the call will route in the 30 channels in pri .it takes from 5th channel or it moves the first four channels to 5th
channel.


And i have major doubt on isdn pri down speeding .


what are the reasons for downspeeding in isdn pri especially in multipoint .


plz suggest me asap .its very appericiating


regards
ROYAL

[Joe Vallender]

Whatever equipment is assigning the available channels on your PRI to your calls will pick which ones to use. Those channels will be busy for the duration of the call. Another call will be assigned another range of available channels. Downspeeding generally is done by the endpoint(s) when a problem is detected on one of the paths of one or more of the channels. The endpoint will drop that call (channel) and (re)negotiate with the other endpoint for the new call rate. The problem on the call(channel) path causing the problem may not be on your PRI but anywhere in the end-to-end path to the other endpoint. In a multi-point call where one end is using a PRI and is connecting several endpoints together, it would be up to the endpoints to handle the dropping of some channels (downspeeding) to make room for additional endpoints to be added to the call. The PRI would not care how the channels are used, the endpoint equipment would control the use of the channels.

[ROYAL]

hii joe,


can u give some more indepth detail information on downspeeding on pri.i was facing downspeeding a problem in multipoint continously.........suggest me any reasons .

[Joe Vallender]

We have to know what equipment is involved and the scenario where you are getting the downspeeding problems. Polycom video units only support downspeeding during initial call setup. Once the call is established Polycoms will not downspeed and renegotiate the new rate, whereas Tandbergs do support this. Of course, both ends of the call have to support ongoing call downspeeding so if your multipoint calls are to different vendor equipment, they might not support it and drop that leg of your multi-point call.
Can you describe your network connection on your multipoint hosting side and the equipment (vendor,model,software version) there? What vendors endpoints (model, sw ver) are you multi-pointing to? What is the scenario when you are having the downspeeding issue (adding a new leg to the call, or one site is being downspeeded (due to line errors))?