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New Member

Hardware / Software Conference Bridge question


Can someone please inform of the main diffrences between hardware and software conference bridge. I was under the impression that the HW / IOS conf bridge allowed extra conf facilities out of the gateway and the SW bridge catered for internal conf facilities within the cluster??


Cisco Employee

Re: Hardware / Software Conference Bridge question

Hi Simon,

The basic difference is that the software conference bridge is controlled by Call Manager(CUCM). IPVMS service has to be activated for this. And it supports 48 streams maximum. And note that the software conference bridge can support only g711 codec.

The hardware conference bridge uses the local DSPs for stream mixing. Of course you need to allocate DSPs for this. And also hardware conference bridge can support multiple codecs since it can do transcoding as well.

So if you want to use the hardware conference bridge, then you will have to allocate DSPs on the gateway (called DSP farm), and register these DSP farm to the call manager. Once this is done, you need to add the haredware conference bridge to a Media resource group and media resource grup list and add it to the phones in the phones page on CUCM (devices-->Phones--> MRGL).

So, when the phone has to use a conference bridge for a conference call, it looks at its MRGL,  and if it finds any hardware/software conference bridge present, then the phone will invoke the hardware/software conferece bridge for that conference call.

the following links might help.

Cisco Employee

Re: Hardware / Software Conference Bridge question

hope this helps

New Member

Re: Hardware / Software Conference Bridge question

Thanks both Manoj and James.....excellent stuff Manoj o the CUCM SW supported conf bridge info, just what I needed

Re: Hardware / Software Conference Bridge question

Software CFB's are hosted by CUCM servers and only support the G.711 codec.

Hardware CFB's are hosted by DSP's and support a wider range of codecs.

I generally only use software CFB's in smaller single site deployments which use only G.711 and where the CUCM servers have plenty of ooomph in reserve.

For larger multi-site deployments where multiple codecs are used and you need to be wary about the load of CUCM servers hardware CFB's are a better bet.