PVDM capacity questions

[robert-knapp]

Question 1

I have a 2801 with (1) PVDM2-16 and (2) VWIC2-4FXO cards. With this hardware configuration I should have 8 available PVDM channels...right? So why can't I add one conference session, for example:

!

dspfarm profile 1 conference

maximum sessions 1

!

My only option for maximum sessions is "0"

Question 2.

I have a different 2801 that doesn't have any VWICs on it but it does have (1) PVDM2-16. This gateway has a conference profile that allows "maximum sessions 8". The CCM SRND states that the PVDM2 can support 8 participants (I assume per session???). 8 Participants x 8 Sessions = 64. Obviously these numbers don't add up. What am I missing here????

[MARTIN STREULE]

Answer 1:

2 x 4 FXO card = 8 calls = 16 channels (send&receive)

You need at least another PVDM2-8 for conferencing.

Answer 2:

One DSP chip can support 8 sessions (G711) or 2 sessions (G729) with max. 8 participants.

That's the way it is. The numbers are for calls only, not conferences.

Two things to remember:

You have to change the service parameter in CUCM to allow 8 participants.

The entire DSP chip is used for conference exclusively.

Hope that helps somehow.

I hope you know the DSP calculator:

http://www.cisco.com/pcgi-bin/Support/DSP/cisco_prodsel.pl

Cheers,

Martin

[paolo bevilacqua]

Actually, for pvdm2-xx the suffix number (8, 16 32, 48, 64) can be taken directly as the number of voip calls that can be some with g711 and other low/medium complexity codecs. There is no need to divide by two.

For confirmation, use the dsp calculator on cisco website, also useful to determine conferencing dsp sizing.

[Jaime Valencia]

did you enabled the dsp services dspfarm on the right voice card?

if you enable the services in a card where no PVDMs are you won't be able to use them for CFB or XCODING

do a sh diag to verify on which card the dsps are and enable the dspfarm services on that card, then try again

you can do a sh voice dsp to look at the current allocation and determine if you still have free channels

HTH

[MARTIN STREULE · Accepted solution]

One PVDM2-16 has one DSP chip on the PVDM module.

One separate chip is needed for conferencing. You need at least another PVDM2-8.

If you actually use the DSP calculator (I guess nobody does) you see that the minimum requirement for this is

1 PVDM2-16 and 1 PVDM2-8.

No config can save you...

/Martin

[robert-knapp]

Thanks! I didn't know that you need a separate chip. Now it all makes sense.