RE: Dumb question - what do the codec command do on dial peer

From: Hunt Lee (Hunt.Lee@telecom.co.nz)
Date: Thu Aug 05 2004 - 18:37:37 GMT-3


So for the 'codec <codec type> byte <x>' command...

It is changing the 'payload', not 'rate', right?

I'm a little confused, what's the rate of 8bytes of G.729 refer to then?

-----Original Message-----
From: Edwards, Andrew M [mailto:andrew.m.edwards@boeing.com]
Sent: Friday, 6 August 2004 9:34 a.m.
To: Bob Sinclair; Hunt Lee
Cc: ccielab@groupstudy.com
Subject: RE: Dumb question - what do the codec command do on dial peer
actually represent?

Thanks Bob. Yep. Reading the chart myself... Its 20bytes. 8)

-----Original Message-----
From: Bob Sinclair [mailto:bsinclair@netmasterclass.net]
Sent: Thursday, August 05, 2004 2:23 PM
To: Hunt Lee; Edwards, Andrew M
Cc: ccielab@groupstudy.com
Subject: Re: Dumb question - what do the codec command do on dial peer
actually represent?

Hunt,

You can determine the default codec bandwidth and payload size by doing
a show dial-peer voice command (after configuring either a voip or vofr
dial-peer). By default, the g729r8 codec sends at 8000 bps. The
default payload is 20 bytes for voip and 30 bytes for vofr. The best
discussion of this I have seen in print is in the Cisco Press book Cisco
Voice over Frame Relay, ATM and IP

by Steve McQuerry, et.al.

HTH,

Bob Sinclair
CCIE #10427, CISSP, MCSE
www.netmasterclass.net

----- Original Message -----
From: "Hunt Lee" <Hunt.Lee@telecom.co.nz>
To: "Edwards, Andrew M" <andrew.m.edwards@boeing.com>
Cc: <ccielab@groupstudy.com>
Sent: Thursday, August 05, 2004 5:13 PM
Subject: RE: Dumb question - what do the codec command do on dial peer
actually represent?

> Oh...
>
> Isn't the default for G.729 is 8byte whereas G.711 is 64bytes?
>
> Can you please elaborate a bit more on where do you find the payload
> of G.729 to be 30bytes?
>
> Or any URL would be great too!!!
>
> Thanks,
> Hunt
>
> -----Original Message-----
> From: Edwards, Andrew M [mailto:andrew.m.edwards@boeing.com]
> Sent: Friday, 6 August 2004 3:52 a.m.
> To: Hunt Lee
> Subject: RE: Dumb question - what do the codec command do on dial peer

> actually represent?
>
> I don't know if it came across correctly, but the default is
> 30bytes... You are lowering it to 10 bytes therefore lowering the
> processing delay but increasing the affect excessive jitter can have
> on the voice quality. Basically the packets are processed faster, but

> they playback at the same rate, so when the playback buffer is smaller

> (per packet SMALLER), then delay variation can affect the overall
> buffer... Maybe even allowing the buffer to starve (silence)...
>
> HTH
>
> -----Original Message-----
> From: Hunt Lee [mailto:Hunt.Lee@telecom.co.nz]
> Sent: Wednesday, August 04, 2004 6:15 PM
> To: Edwards, Andrew M; Joe Rinehart
> Cc: ccielab@groupstudy.com
> Subject: RE: Dumb question - what do the codec command do on dial peer

> actually represent?
>
>
> Okay. Thanks for your explanation.
>
> But if the command increases both 'bandwidth' & 'delay', what's the
> point of the IOS command?
>
> I'm sure if it is a lose-lose situation, nobody will ever want to use
> that command, right?
>
> Thanks,
> L.
>
> -----Original Message-----
> From: Edwards, Andrew M [mailto:andrew.m.edwards@boeing.com]
> Sent: Thursday, 5 August 2004 12:20 p.m.
> To: Hunt Lee; Joe Rinehart
> Cc: ccielab@groupstudy.com
> Subject: RE: Dumb question - what do the codec command do on dial peer

> actually represent?
>
> The default BW for G.729ar8 is 8 kbits per second.
>
> The default byte count per sample for 729ar8 I believe is 30 bytes
>
> The larger the number of bytes encoded per sample will translate into
> larger delays between packets (e.g. longer to process)
>
> I am sure there is more too it, but that's the general idea (at least
> that's how I understand it). The deeper understanding is how the
> encoded sample size has an effect on setting up traffic shaping on a
> WAN such that you do not starve out voice packets because of the added

> delay of encoding more bytes per sample.
>
> andy
>
> -----Original Message-----
> From: Hunt Lee [mailto:Hunt.Lee@telecom.co.nz]
> Sent: Wednesday, August 04, 2004 2:38 PM
> To: Joe Rinehart
> Cc: ccielab@groupstudy.com
> Subject: RE: Dumb question - what do the codec command do on dial peer

> actually represent?
>
>
> Hi Joe,
>
> Thanks for your reply.
>
> But my question is say since the default bandwidth for G.729 is
> 8bytes, now I have increase the bandwidth per call to 10bytes.
>
> By increasing to 10bytes, does it increase the delay or decrease the
> delay per call?
>
> Thanks,
> L.
>
>
> -----Original Message-----
> From: Joe Rinehart [mailto:jjrinehart@hotmail.com]
> Sent: Thursday, 5 August 2004 9:36 a.m.
> To: Hunt Lee
> Subject: Re: Dumb question - what do the codec command do on dial peer

> actually represent?
>
> chooses the dial peer codec and the packet size
> ----- Original Message -----
> From: "Hunt Lee" <Hunt.Lee@telecom.co.nz>
> To: <ccielab@groupstudy.com>
> Sent: Wednesday, August 04, 2004 2:26 PM
> Subject: Dumb question - what do the codec command do on dial peer
> actually represent?
>
>
> > Hi guys,
> >
> >
> >
> > What does this command do?
> >
> >
> >
> > 'codec g729ar8 bytes 10'
> >
> >
> >
> > I look it up on CCO and any books I can find, yet I still don't
> > quite understand what it achieve.
> >
> >
> >
> > Greatly appreciated if anyone can shed some light on this.
> >
> >
> >
> > Cheers,
> >
> > L.
> >
> >
> >
> >
> >
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