[cisco-voip] PVDM2 DSP (5510) Processing of Voice Sessions

[Pritchard, Jon]

I'm looking to better understand the algorithms if not actually find a
reference doc regarding the dynamics of voice session allocations on
PVDM2 (5510) DSP's for IOS 12.4 as seen via "show voice dsp group all".
This does not seep to be documented anywhere in CCO. 

Here's an example of what I'm talking about (supporting config/show info
is below): 
- Assume a remote site 2821 with two PVDM2-64's and a single PRI, 16
transcoders and 10 conferences. 
- voice-card in the default flex mode codec complexity 
- IOS allocates 16 signaling channels per 5510 DSP (16 on DSP 1 and 7 on
DSP 2). 
- Each 5510 DSP has 240 "credits" for work. 
- Each g711 call requires 15 credits 
- Each call that is or has downspeed to g729a requires 30 credits. 
- Each 5510 DSP that has "shared credits" available is eligible to
support voice sessions. 
- The IOS tends to assigns calls to DSP's that already have signaling
channels allocated but will somewhat arbitrarily start using a different
DSP that has available shared credits regardless of whether it has
signaling channels assigned or not. 
- Voice sessions have been allocated ton DSP 2 and DSP 5 while there are
still plenty of credits available on DSP 1. 

Any insight as to the algorithm behind this arbitrary behavior would be
appreciated. 

Jon

++++

#sh run (excerpt) 
. 
. 
voice-card 0 
dspfarm 
dsp services dspfarm 
no local-bypass 
. 
. 
controller T1 0/0/0 
framing esf 
linecode b8zs 
pri-group timeslots 1-24 service mgcp 
. 
. 
dspfarm profile 2 transcode 
codec g711ulaw 
codec g711alaw 
codec g729ar8 
codec g729abr8 
maximum sessions 16 
associate application SCCP 
! 
dspfarm profile 1 conference 
codec g711ulaw 
codec g711alaw 
codec g729ar8 
codec g729abr8 
maximum sessions 10 
associate application SCCP 
. 
. 


#show voice dsp group all 
dsp 1: 
State: UP, firmware: 4.4.20 
Max signal/voice channel: 16/16 
Max credits: 240 
Group: FLEX_GROUP_VOICE, complexity: FLEX 
Shared credits: 180, reserved credits: 0 
Signaling channels allocated: 16 
Voice channels allocated: 3 
Credits used: 60 
Voice channels: 
Ch02: voice port: 0/0/0:23.23, codec: g711ulaw, credits allocated: 30 
Ch03: voice port: 0/0/0:23.20, codec: g711ulaw, credits allocated: 15 
Ch04: voice port: 0/0/0:23.19, codec: g711ulaw, credits allocated: 15 
Group: FLEX_GROUP_XCODE, complexity: MEDIUM 
Shared credits: 0, reserved credits: 0 
Transcoding channels allocated: 0 
Credits used: 0 

dsp 2: 
State: UP, firmware: 4.4.20 
Max signal/voice channel: 16/16 
Max credits: 240 
Group: FLEX_GROUP_VOICE, complexity: FLEX 
Shared credits: 45, reserved credits: 0 
Signaling channels allocated: 11 
Voice channels allocated: 2 
Credits used: 45 
Voice channels: 
Ch01: voice port: 0/0/0:23.22, codec: g711ulaw, credits allocated: 30 
Ch02: voice port: 0/0/0:23.18, codec: g711ulaw, credits allocated: 15 
Group: FLEX_GROUP_XCODE, complexity: MEDIUM 
Shared credits: 0, reserved credits: 150 
Transcoding channels allocated: 0 
Credits used: 0 

dsp 3: 
State: UP, firmware: 4.4.20 
Max signal/voice channel: 16/16 
Max credits: 240 
Group: FLEX_GROUP_XCODE, complexity: MEDIUM 
Shared credits: 0, reserved credits: 240 
Transcoding channels allocated: 0 
Credits used: 0 

dsp 4: 
State: UP, firmware: 4.4.20 
Max signal/voice channel: 16/16 
Max credits: 240 
Group: FLEX_GROUP_VOICE, complexity: FLEX 
Shared credits: 90, reserved credits: 0 
Signaling channels allocated: 0 
Voice channels allocated: 0 
Credits used: 0 
Group: FLEX_GROUP_XCODE, complexity: MEDIUM 
Shared credits: 0, reserved credits: 150 
Transcoding channels allocated: 0 
Credits used: 0 

dsp 5: 
State: UP, firmware: 4.4.20 
Max signal/voice channel: 16/16 
Max credits: 240 
Group: FLEX_GROUP_VOICE, complexity: FLEX 
Shared credits: 210, reserved credits: 0 
Signaling channels allocated: 0 
Voice channels allocated: 1 
Credits used: 30 
Voice channels: 
Ch01: voice port: 0/0/0:23.1, codec: g711ulaw, credits allocated: 30 

dsp 6: 
State: UP, firmware: 1.0.6 
Max signal/voice channel: 16/16 
Max credits: 240 
Group: FLEX_GROUP_CONF, complexity: CONFERENCE 
Shared credits: 0, reserved credits: 240 
Conference session: 2 
Credits used: 0 

dsp 7: 
State: UP, firmware: 1.0.6 
Max signal/voice channel: 16/16 
Max credits: 240 
Group: FLEX_GROUP_CONF, complexity: CONFERENCE 
Shared credits: 0, reserved credits: 240 
Conference session: 2 
Credits used: 0 

dsp 8: 
State: UP, firmware: 1.0.6 
Max signal/voice channel: 16/16 
Max credits: 240 
Group: FLEX_GROUP_CONF, complexity: CONFERENCE 
Shared credits: 0, reserved credits: 240 
Conference session: 2 
Credits used: 0 




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