You may be correct but I don't know how this would work. What populates
each queue? Do fragmented packets go in one and non-fragmented in the
other? That doesn't make much sense to me.
However, upon more reflection maybe it does make some sense. If the voice
packets aren't fragmented then they'd all end up in one queue while all
other traffic that was fragmented would be in the other. Within a queue
FIFO rules would apply and the queues would be serviced in a round robin
fashion. This would allow more frequent attention to the voice packets.
Now, what happens when I also have LLQ configured?? In that case you have
two classes: one for voice which gets a strict priority queue and the other
for everything else. I have WFQ applied to the second class. How does dual
FIFO apply here?
I just don't see how LLQ (or CBWFQ), WFQ, and dual FIFO can work together.
In light of recent events, my mind has used up a lot of its processing power
on other things. Perhaps it's just too depleted to comprehend this yet.
Actually, I just need a really good nap.
Thanks,
John
On Thu, 13 Sep 2001 17:57:14 -0400, Priscilla Oppenheimer wrote:
| 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
|
|
|
|
_______________________________________________________
http://inbox.excite.com
Message Posted at:
http://www.groupstudy.com/form/read.php?f=7&i=19880&t=19691
--------------------------------------------------
FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html
Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
