[cisco-voip] Understanding DSP Resources

[Ryan Ratliff]

This depends on what hardware you have.  One of the newer ISRs will  
have the on-board DSPs that get allocated for analog ports.  An older  
router using a NM-2V or similar module will have the required DSPs on  
the NM but these particular DSPs don't support the DSPFarm  
configuration.  For newer ISRs the same DSPs used for media resources  
are used for all voice ports.

-Ryan

On Mar 6, 2008, at 9:58 AM, Lelio Fulgenzi wrote:

Someone mentioned that if you only have analog ports, i.e. FXS/FXO -  
you do
not require DSPs. That was very interesting.

Lelio
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--------
Lelio Fulgenzi, B.A.
Senior Analyst (CCS) * University of Guelph * Guelph, Ontario N1G 2W1
(519) 824-4120 x56354 (519) 767-1060 FAX (JNHN)
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keys
is inversely
related to the amount of caffeine ingested in the last 30 minutes.

----- Original Message -----
From: "James Buchanan" <jbuchanan at ctiusa.com>
To: <kenny.kant at running-config.com>; <cisco-voip at puck.nether.net>
Sent: Thursday, March 06, 2008 12:31 AM
Subject: Re: [cisco-voip] Understanding DSP Resources


> Hello,
>
> Good questions.
>
> On the first, DSPs never come built into the board on ISR routers.
>
> On the second, you are correct on that. Different types of calls and
> different codec complexities require different numbers of DSP  
> channels.
>
> On the third, DSPS are used for providing hardware conferencing
> resources to 1) lessen the burden on the Callmanager server, 2)  
> save WAN
> bandwidth by offloading conferencing to a local site. DSPs may also be
> used to provide a media termination point when one is required. MTP
> resources are used for supplementary services such as DTMF and call
> transfer in certain scenarios, such as when a SIP provider is being
> used. Again, having the MTP on the router lessens the burden on the
> Callmanager server.
>
> DSPs are always required to do transcoding, etc., on the ISR.
>
> I would suggest as good reading the SRND for pretty much any  
> version of
> CallManager, but the one for UCM 6.X will be most informative.
> http://www.cisco.com/go/srnd will get you there.
>
> Thanks,
>
> James
>
> -----Original Message-----
> From: cisco-voip-bounces at puck.nether.net
> [mailto:cisco-voip-bounces at puck.nether.net] On Behalf Of Kenny Kant
> Sent: Wednesday, March 05, 2008 11:21 PM
> To: cisco-voip at puck.nether.net
> Subject: [cisco-voip] Understanding DSP Resources
>
> I have a basic question on the general purpose of DSP's  and when they
> are required.  From reading on this list and NetPro and other books I
> understand that DSP (Digital Signal Processors ? ) are hardware chips
> that come shippped on SIMM type modules.  Do they ever come built onto
> the board on the newer ISR's  ?
>
> The main purpose of these chips are to "encode" calls that come in  
> over
> PSTN interfaces into PCM audio that can be then transmitted via voice
> call? Correct?  This is why sizing DSP's to match your incoming PSTN
> sourced channels is important.  ???
>
> Another function of these things are to transcode streams to and from
> higher compression streams such as G729.00  These are done via DSP
> farms.  I hear alot about DSP farms used for conferencing ..etc  
> what are
> some other purposes here.  In general, if you are not doing advanced
> call conferencing and/or transcoding is there a need for DSP's in CME
> system for general calls ephone to ephone ?
>
> Last, can a ISR do any type of transcoding in software? or are DSP's
> always required?
>
>
> Thanks for helping out a newbie :)
>
> Kenny
>
>
>
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