configuring DSP resources on router

Answered Question
Dec 5th, 2007

i have a ISR router running 12.4 software with a PVDM2-8, i want to configure the router as a conferencing only dsp, the dsp calculator suggests the follwing config

CLI Information for Optimal results.


To match the DSP Calculator configuration with your router, enter the following commands in configuration mode in your Cisco 2801 router:


Optimal Results

voice-card 0

codec complexity flex

Set of Conferencing/Transcoding commands when used with PVDM2-XX DSPs:

sccp local <local interface>

sccp ccm <call manager IP address> identifier <ccm ID #> version <version #>

sccp

!

sccp ccm group 999

bind interface <local interface>

associate cme <cme ID #> priority 1

associate profile <conferencing profile ID #> register <conference bridge name>

!

dspfarm profile <conferencing profile ID #> conference

maximum sessions 4

associate application SCCP


when i configure these setting it will only allow me to set max sessions to 1, this is the only option, but in the calculator recomendation it says 4 ? any clever people out there that may be able to shed some light on this.

Correct Answer by allan.thomas about 9 years 2 months ago

This behaviour seems very perculiar, have you tried removing and re-applying the DSP profile?


When you removed the codecs did you shut the profile and re-apply SCCP? Firstly shutdown the profile, then shut sccp with a 'no sccp' from global, then re-apply 'sccp'. Once you have done this try creating the profile again ensuring that only G711 codecs are selected.


Can remove the dspfarm and re-create it with medium complexity, providing you remove the unwanted codecs from the list, this should still allow you 4 CFBs.


Regards

Allan.

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Overall Rating: 5 (1 ratings)
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allan.thomas Wed, 12/05/2007 - 08:37

For flex complexity the PVDM2-8 will certainly support 4 G711 only Conference Bridges, the higher the complexity the less number of CFBs it can support.


The fact that you are only able to configure the maximum sessions to 1 suggests that you have voice-card/modules installed in the gateway. If this is the case then DSPs will be automatically reserved for these modules before you are able to configure your DSPFARM. Do you have such modules installed?


Please provide a 'show voice port summary'.


Regards

Allan.


littledavewhite Wed, 12/05/2007 - 08:53

hi alan

the show voice summary command

note we have no voice modules in the gateway, just a PVDM 2-8, we are using the gateway as srst just for local calls if wan fails, but no local pstn on gateway.


CS-CR-2801-GW#show voice port summary

IN OUT

PORT CH SIG-TYPE ADMIN OPER STATUS STATUS EC

========= == ============ ===== ==== ======== ======== ==

50/0/1 1 efxs up up on-hook idle y

50/0/2 1 efxs up up on-hook idle y

50/0/3 1 efxs up up on-hook idle y

50/0/4 1 efxs up up on-hook idle y

50/0/5 1 efxs up up on-hook idle y

50/0/6 1 efxs up up on-hook idle y

50/0/7 1 efxs up up on-hook idle y

50/0/8 1 efxs up up on-hook idle y

50/0/9 1 efxs up up on-hook idle y

50/0/10 1 efxs up up on-hook idle y

50/0/11 1 efxs up up on-hook idle y

50/0/12 1 efxs up up on-hook idle y

50/0/13 1 efxs up up on-hook idle y

50/0/14 1 efxs up up on-hook idle y

50/0/15 1 efxs up up on-hook idle y

50/0/16 1 efxs up up on-hook idle y

50/0/17 1 efxs up up on-hook idle y

50/0/18 1 efxs up up on-hook idle y

50/0/19 1 efxs up up on-hook idle y

50/0/20 1 efxs up up on-hook idle y

50/0/21 1 efxs up up on-hook idle y

50/0/22 1 efxs up up on-hook idle y

50/0/23 1 efxs up up on-hook idle y

50/0/24 1 efxs up up on-hook idle y

50/0/25 1 efxs up up on-hook idle y

50/0/26 1 efxs up up on-hook idle y

50/0/27 1 efxs up up on-hook idle y

50/0/28 1 efxs up up on-hook idle y

50/0/29 1 efxs up up on-hook idle y

50/0/30 1 efxs up up on-hook idle y

50/0/31 1 efxs up up on-hook idle y

50/0/32 1 efxs up up on-hook idle y

50/0/33 1 efxs up up on-hook idle y

50/0/34 1 efxs up up on-hook idle y

50/0/35 1 efxs up up on-hook idle y

50/0/36 1 efxs up up on-hook idle y

50/0/37 1 efxs up up on-hook idle y

50/0/38 1 efxs up up on-hook idle y

50/0/39 1 efxs up up on-hook idle y

50/0/40 1 efxs up up on-hook idle y


!

sccp local Loopback100

sccp ccm 172.31.10.1 identifier 1 version 4.0

sccp ccm 172.31.140.2 identifier 2 version 4.0

sccp

!

sccp ccm group 1

associate ccm 2 priority 2

associate ccm 1 priority 1

associate profile 1 register CHURCHSIDE-CONF

registration retries 20

registration timeout 30

keepalive retries 10

connect retries 30

connect interval 30

switchback method immediate

!

dspfarm profile 1 conference

codec g711ulaw

codec g711alaw

codec g729ar8

codec g729abr8

codec g729r8

codec g729br8

maximum sessions 1

associate application SCCP

!

jbarcena Wed, 12/05/2007 - 09:10

If I remember correctly the PVDM2-8 only has 1/2 DSP, the problem here is that a conference allocates a complete DSP that is why you are not allowed to configure more than 1 session. In order to have more sessions you will require more resources.


HTH


//Jorge

allan.thomas Wed, 12/05/2007 - 09:31

The PVDM2-8 is listed as having ½ a DSP because it has a DSP that has half the processing capacity of the PVDM2-16.


For example, if the DSP on a PVDM2-8 is configured for G.711, it can provide (0.5 * 8) bridges/DSP = 4 conference bridges.


When configured to accept both G.711 and G.729 calls, a single DSP provides 2 conferences because it is also reserving its resources for performing transcoding of streams.


Remove all codecs from the within the Conferencing profile with the exception of G711, and see what sessions are available then? Because you are using mixed codecs you are limiting the sessions.


Cisco 2801 routers use the following PVDMs:


•PVDM2-8 (1 DSP)


•PVDM2-16 (1 DSP)


•PVDM2-32 (2 DSPs)


•PVDM2-48 (3 DSPs)


•PVDM2-64 (4 DSPs)


Conferencing needs dedicated DSP resources. A DSP will support eight conference calls on a G.711 codec, or two conference calls on a G.729/G.711 configuration. (The PVDM2-8 will support four conference calls on G.711 or 1 conference call on G.729/G.711.) There is a maximium of eight participants per conference. Up to 30 conferencing calls can be supported on the Cisco 2801 routers.


The above is taken from the following document link:-


http://www.cisco.com/en/US/partner/docs/routers/access/1700/1751/software/feature/guide/dsp_cn.html


Regards

Allan.

littledavewhite Wed, 12/05/2007 - 09:38

Hi Alan


I already tried removing the other codecs but the same issue, only allows me to put one in ?

Correct Answer
allan.thomas Wed, 12/05/2007 - 10:57

This behaviour seems very perculiar, have you tried removing and re-applying the DSP profile?


When you removed the codecs did you shut the profile and re-apply SCCP? Firstly shutdown the profile, then shut sccp with a 'no sccp' from global, then re-apply 'sccp'. Once you have done this try creating the profile again ensuring that only G711 codecs are selected.


Can remove the dspfarm and re-create it with medium complexity, providing you remove the unwanted codecs from the list, this should still allow you 4 CFBs.


Regards

Allan.

littledavewhite Wed, 12/05/2007 - 11:37

hi alan thanks for your time on this post, i'm back on site tomorrow so will try and test your suggestions. I will let you know how i get on.


littledavewhite Thu, 12/06/2007 - 02:00

Hi Alan


it worked, shutting down the profile and sccp then removing the additional G729 codecs. I now have the option of 1 to 5 sessions for conferencing on the PVDM 2-8


Great work

Dave white


allan.thomas Thu, 12/06/2007 - 03:45

Great to know that it worked out for you, thanks for the rating and best of luck.


Best Regards

Allan.

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