quesion about Hardware conference bridge from dspfarm

[ciscoroyzhang]

                   hi there,  I know that the CUCM software conference bridge can handl g711 calls. and in what circumstance we need to use the hardware conferecne bridge?  the call from ISND will be converted as g711 before it send to the phones, and I don't see there is need to configure the Hardware conference bridge in normal day to day conference call. 

also on same topic of DSP,  if I have PVDM3-32 and PVDM-64 installed on same router and I would like to configure the Transcode on PVDM3-64, can I have the options to choose?  

Many Thanks.

Roy

[ronpatel]

Hi Roy,

Hardware conference bridges can support multiple  low bit-rate (LBR) stream types such as G.729 or G.723. This capability  enables some hardware conference bridges to handle mixed-mode  conferences. In a mixed-mode conference, the hardware conference bridge  transcodes G.729 and G.723 streams into G.711 streams, mixes them, and  then encodes the resulting stream into the appropriate stream type for  transmission back to the user.

Regards

Ronak Patel

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[ciscoroyzhang]

Hi Ronak,  Thanks for the prompt reply.

In my enviroment, we have standard cisco IP phone, most of them are 7945. between the site G729 and within same site G711, I don't see there is need to configure the hardware dsp. am I correct here?  in another words, in which circunstance, the conferece call will have pariticpate come with G723 or evern g722, iblc?  

Thanks

Roy

[Ayodeji Okanlawon]

Like I mentione din my post, in this scenario you will need hardware conf bridge resources. When the user on G729 attempts to conference a user on G711, the region between the user on G729 to the software conference bridge is set to use G729, now software cfb doesnot support G729, hence conference will fail..

You dont have to worry about G722 or Ilbc since you dont have it in your environment

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[Ayodeji Okanlawon · Accepted solution]

Hi Roy, there may be scenarios where you have some users configured to use G729. In this case when these users attempt to join or use the conference bridge resoruces, this will fail if you only have software conference bridge. hence it i always advisable to have dsp resources on the user's local router for hardware conference bridge.

Also, when configuring hardware and software conference bridge, ensure you do not assign them to the same MRG. Otherwise conferece that require hardware conf bridge will fail sometimes. This is because when they are assigned to the same MRG, callmanager selects them in a round robin fashion. So ensure you have seperate MRG for soft and hardware conf resources.

Yes you can mix different PVDM3 modules in the same chassis; however,  Each DSP chip in the PVDM3 hardware has to be assigned to one task or another. For example. you cannot have the same DSP chip (of which there are two on the -32 or four on the -64 part) assigned to do conferencing and media termination simultaniously. Be sure that you use the DSP Calculator to understand what you need.

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[ciscoroyzhang]

Hi Aokanlawon, thanke for the detailed explaination, please see my comment within.

"Hi Roy, there may be scenarios where you have some users configured to use G729. In this case when these users attempt to join or use the conference bridge resoruces, this will fail if you only have software conference bridge. hence it i always advisable to have dsp resources on the user's local router for hardware conference bridge"  

Makes sense

"Also, when configuring hardware and software conference bridge, ensure you do not assign them to the same MRG. Otherwise conferece that require hardware conf bridge will fail sometimes. This is because when they are assigned to the same MRG, callmanager selects them in a round robin fashion. So ensure you have seperate MRG for soft and hardware conf resources".

Good suggestion, I always used Hardware-MG and Software-MG, but thanks to mention here the reason behind it. 

"Yes you can mix different PVDM3 modules in the same chassis; however,  Each DSP chip in the PVDM3 hardware has to be assigned to one task or another. For example. you cannot have the same DSP chip (of which there are two on the -32 or four on the -64 part) assigned to do conferencing and media termination simultaniously. Be sure that you use the

DSP Calculator to understand what you needYes you can mix different PVDM3 modules in the same chassis; however,  Each DSP chip in the PVDM3 hardware has to be assigned to one task or another. For example. you cannot have the same DSP chip (of which there are two on the -32 or four on the -64 part) assigned to do conferencing and media termination simultaniously. Be sure that you use the DSP Calculator to understand what you need"

I am still a bit confused here: we have router equiped with PVDMIII-16, it allows me to configure the 1xTranscode and 1x conference bridge. my understanding is that those PVDM will be used first for ISDN line, if it there is new call from ISDN requiring DSP resouce, router will always serve those requres first. then to hareware dspfarm. Furthermore, if the dsp has been used for the conference bridge then it will not be available for theTranscode task if both hardware have been configure from same PVDM chips. am I right?

Thanks 

Roy

[Ayodeji Okanlawon]

Roy,

Yes. The PVDM3 modules have a universal firmware image that allows sharing DSP resources between transcoding, voice, and conference calls.  A single dsp can be shared to suppor transcoding, conferencing and voice call termination at the same time. This is where the PVDM3 perform better than the PVDM2. In the PVDM2, If a DSP is assigned for a conferencing session, it cannot be used for transcoding or voice- calls at the same time.

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"There is a wideness in God's mercy Like the wideness of the sea.There's a kindness in His justice Which is more than liberty"