Voice is in a different queue than data, so there are two queues (hence the
dual)??
At 03:09 PM 9/13/01, John Neiberger wrote:
>I understand that concept but I haven't been able to connect that to the
>dual FIFO queue. How does fragmentation relate to the dual queue? If I
>follow Cisco's suggestion and use a fragmentation size of 1600 then no
>fragmentation is actually occurring, yet the dual FIFO queue is
>implemented.
>
>I have this nagging feeling that I'm just missing something that I
>should have figured out by now.
Or maybe the documentation writer was just missing something?? ;-)
Priscilla
>Thanks,
>John
>
> >>> "MADMAN" 9/13/01 9:01:55 AM >>>
>The bottom line is you fragment data packets, never voice, so that a
>voice packets, which are small, never get queued behind a 1500 byte
>packet. The rule of thumb I think is you don't want more than 150ms
>delay in any voice packets or you may as well dump it.
>
> dave
>
>Stephen Skinner wrote:
> >
> > the only thing i could find was this
> >
> > http://www.cisco.com/warp/public/788/voice-qos/voip-ov-fr-qos.pdf
> >
> > which says
> >
> > "Turn on fragmentation for low speed links (less than 1.5Mbps).
> > Set the fragment size so voice packets are not fragmented and do not
> > experience a serialization delay greater than 20 ms.
> >
> > Lowest Link Speed in Path Recommended Fragmentation Size
> >
> > 56Kbps 70 bytes
> > 64Kbps 80 bytes
> > 128Kbps 160 bytes
> > 256Kbps 320 bytes
> > 512Kbps 640 bytes
> > 768Kbps 1000 bytes
> > 1536Kbps 1600 bytes
> >
> > Note: For 1536 Kbps, no fragmentation is technically needed, but
> > fragmentation is needed to enable the dual first-in, first-out
> > (FIFO) queueing system to ensure voice quality. A fragment size of
>1600
> > bytes enables the dual FIFO, but since 1600 bytes is
> > higher than the typical serial interface maximum transmission unit
>(MTU),
> > large data packets are not fragmented.
> >
> > from what it says it`s just multple "stack" queue
> >
> > sorry i can`t be of more help..
> >
> > Cheers
> >
> > steve
> > >From: "John Neiberger"
> > >Reply-To: "John Neiberger"
> > >To: [EMAIL PROTECTED]
> > >Subject: Dual FIFO? [7:19691]
> > >Date: Wed, 12 Sep 2001 18:34:53 -0400
> > >
> > >When configuring VoIP on T-1 links, I see that CCO suggests turning
>on
> > >frame relay fragmentation with a fragment size of 1600 simply to
>turn on
> > >the dual fifo queue. What is that? I'm familiar with the single
>fifo
> > >but what is dual fifo and how does it work?
> > >
> > >I've searched CCO and all I can find is how to turn it on. I have
>yet
> > >to find any sort of explanation.
> > >
> > >thanks!
> > >
> > >John
> > _________________________________________________________________
> > Get your FREE download of MSN Explorer at
>http://explorer.msn.com/intl.asp
>--
>David Madland
>Sr. Network Engineer
>CCIE# 2016
>Qwest Communications Int. Inc.
>[EMAIL PROTECTED]
>612-664-3367
>
>"Emotion should reflect reason not guide it"
________________________
Priscilla Oppenheimer
http://www.priscilla.com
Message Posted at:
http://www.groupstudy.com/form/read.php?f=7&i=19864&t=19691
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