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
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