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North American Network Operators Group

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Re: VoIP QOS best practices

  • From: Stephen Sprunk
  • Date: Mon Feb 10 17:26:26 2003

You are mistaking utilization for congestion.  At the packet level, a link
is congested if it is not immediately available for transmit due to one or
more previous packets still being queued/transmitted.  This transient
congestion causes jitter, VoIP's worst enemy.

Certainly, as utilization rises so will congestion; however, it is quite
common to have transient congestion while overall utilization is minimal.

S


----- Original Message -----
From: "Shawn Solomon" <ssolomon@ind.net>
Sent: Monday, 10 February, 2003 12:54
Subject: RE: VoIP QOS best practices


> If you are in an environment where the uplink is already saturated, or
> nearly so, QOS is necessary.  But QOS only discards packets in times of
> contention.  So, if you don't have contention, you don't need it.  IF
> you have 300 people and 4meg of data all fighting for that t1, it makes
> a world of difference.
>
>
> - -----Original Message-----
> From: Bill Woodcock [mailto:woody@pch.net]=20
> Sent: Monday, February 10, 2003 1:28 PM
> To: Charles Youse
> Cc: nanog@nanog.org
> Subject: RE: VoIP QOS best practices
>
>
>     > But I could conceivably have 10+ voice channels over a T-1, I
> still
>     > don't quite understand how, without prioritizing voice traffic,
> the
>     > quality won't degrade...
>
> Well, of course it all depends how much other traffic you're trying to
> get
> through simultaneously.  Your T1 will carry ~170 simultaneous voice
> streams with no conflict, but you have to realize that they'll stomp on
> your simultaneous TCP data traffic.  But you don't need to protect the
> _voice_...
>
> Look, just do it, and you'll see that there aren't any problems in this
> area.
>
>                                 -Bill
>
> ------------------------------
>





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