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Sep 26th, 2008
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I want to translate 150 calls to G.729 from G.711 by using transcoding feature(IP to IP without TDM). What's the minimal requirement of the hardware(28xx or 38xx)? Do I need to order DSP card(like NP108 on AS53xx)?


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shane.orr Sat, 09/27/2008 - 19:32
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I was playing around with the DSP Calculator which you can look at as long as you have a CCO ID.

Looks like a 3825 populating onboard PVDM's with four PVDM2-64 only supports 128 max transcoding sessions.

Otherwise you can populate a 3845 with 3 NM-HDV-FARM-C36 to give you 180 transcoding session with the expandability for one more NM-HDV-FARM-C36 for an additional 60 transcoding sessions.

Keep in mind I assume you are planning on 150 simultaneous transcoding sessions. Otherwise you can probably scale that back a bit but I dont know the details of your situation are.

The other question I have is you said IP to IP, no TDM. Cisco Phones phones for example can transcode calls between each other without hardware transcoding. Not until you call across to another entity that cannot handle both g.729 and g.711 would a hardware transcoder be required.

David Lin Sat, 09/27/2008 - 21:15
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Actually, the call come from a softswitch by SIP. There is no CCM get involved at the moment but maybe later.

I think I need Unified Border Element(CUBE) as well so that I can send 150 simultaneous calls by G.711 to CUBE from my Softswitch and then transcode to G.729 and send to my termination.

I still have some questions,

1. Can I use NM-HDV2 on 3825 to get more capacity as Cisco Doc say it can support 128 session per NM-HDV2? So I like to install 2 NM-HDV2 on 3825.

2. The maximal license package of CUBE is 100. Let's say I want to support 200 sessions, I have to order 2 packages license then?

3. What's the suggestion for the memory configuraion?

Thank you.

Stoyan Stoitsev Sun, 09/28/2008 - 06:33
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You can have 4 PVDM2-64s onboard the 3845 to support 128 g711<->g729a calls or 96 g711<->g729 calls. To achieve 150 calls I suggest you use an additional NM-HDV2 with 3 PVDM2-64s.

CUBE licensing "is determined either via a capacity-based license that allows a specific number of sessions (e.g. FL-CUBE-25 or FL-CUBE-100), or a platform-based license (e.g. the FL-INTVVSRV licenses) that allows as many sessions as the CPU of the platform can sustain".

3845 supports 750 calls. CUBE bundle for 3845 comes with 512MB RAM and this seems more than enough, though I have no personal experience with so many sessions on a CUBE.

For CUBE check this doc

Best regards,


David Lin Mon, 09/29/2008 - 08:06
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Stoyan, Thank you very much.

Now it's becoming clear to me:

PVDM2-64s is the DSP module can be installed on either motherboard or NM-HDV2 which plugs in the NM slots.

NM-HDV2 must work with PVDM2-64s for transcoding.

When I'm odering Cisco3825 + 4xPVDM2-64s + 1xNM-HDV2, it prompts me below msg:

"Please note that the NM-HDV2 modules do not come with PVDM2 packet voice/fax DSP modules. You will need to order them as an option if you plan to deploy voice. Alternatively, you can configure your NM-HDV2 module to import available PVDM2 DSP modules on the same chassis (on other NM-HDV2 modules). "

Does it mean I need to order DSP module for NM-HDV2? But I try to add 4 more PVDM2-64s, it doesn't let me go.

Also, Can I use 2821 as the platform(3 PVDM2 on board and 4 PVDM2 on NM-HDV2)? How is the maximal transcoding sessions for g.711 to G.729a?

Can you please advise? Thank you.

Stoyan Stoitsev Thu, 10/02/2008 - 11:55
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I suggest you stick with the 38xx platform since it has more powerful CPU. Additionally 2821 supports only two PVDM2 modules onboard. Personally, as I already said, I have no personal experience with so many transcoding sessions on a CUBE so I don't feel that confident in consulting you about the platform.

As for the configuration of your 3845 you should choose 4 PVDM2-64s onboard - that is in the "Integrated DSP Options" section. If you have selected some bundle that already has one PVDM2-64 then you should choose three additional.

For the NM-HDV2 module's PVDM2s you should select them under:

3800 Network Module Options


PVDM2 Options for NM-HDV2 Modules

Btw, you could consider the CUBE bundle for 3845 that has p/n C3845-VSEC-CUBE/K9.

Best regards,

Stoyan Stoitsev


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