Subject: [Ieprep] RE: Summary of IEPREP work and VoIP

From: "King, Kimberly S." <[email-masked]>
Date: Fri, 13 Dec 2002 10:15:20 -0500

> 
> Ahh.  Could you please edit the phrase "QoS devices" to make it clear
> that you are thinking about "SIP-layer-only QoS devices" ?  Not sure 
> what
> the right words would be, but the current ones are confusing.

I agree.  The one I am most familiar with, and could do the job is by Sitara
Networks http://www.sitaranetworks.com/ .  It is sometimes referred to as a
QoS appliance but I definitely see the possibility for confusion in the name
and will indeed think of better terminology.

> 
> Seems plausible enough, with the understanding that it is a matter of
> application-layer blocking for SIP signalling, rather than blocking
> IP packets of any sort.

Absolutely, you block the SIP signaling for lower priority users so their
media streams can't setup and therefore no IP packet blocking involved.

> 
> The two paragraphs above increase clarity a whole lot.  Please maybe 
> take
> some of that text into your next revision of the "VoIP summary" in an
> effort to make things clear all around.

Yes, I'll make another version of the Summary using clearer words and
sections to further indicate form.

> 
> Now, what happens if the same access link is being used concurrently
> for non-SIP/non-VoIP traffic (e.g. a real-time game that is UDP-based
> and lacks congestion avoidance and control) ?
> 
> Is that not still a problem...

With the Sitara Network product (or rather what they told me and what I
witnessed in demo), they can handle this by putting it into a lower priority
queue.  It's kind of a DiffServ approach with application knowledge that
does the packet ordering before hitting the access router.  This is just one
possibility but it exist!

> 
> Maybe add a place holder ?
> 	"Open Issues:
> 		- Initial codec selection
> 		- Codec changes due to congestion

Yes.

> 
> >> Also missing is discussion of the desirability of using 
> link-layer QoS
> >> mechanisms (e.g. IEEE 802.1p) where they exist.
> >
> > One could add that.
> 
> Unless one is trying to rule that out, maybe that could be added.  
> Proposed
> text (edit to taste) might be:
> 
> 	"Link-layer QoS mechanisms should be considered for 
> deployment as part
> 	of an overall system, when such mechanisms exist and 
> can be applied
> 	to a particular IEprep scenario."

Sounds good.

Kimberly
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---

From: RJ Atkinson <[email-masked]>
Date: Fri, 13 Dec 2002 10:33:48 -0500

On Friday, Dec 13, 2002, at 10:15 America/Montreal, King, Kimberly S. 
wrote:
>  It is sometimes referred to as a

Thanks.

>> take some of that text into your next revision of the "VoIP summary" 
>> in an

Hmm.  So one puts this box inline before the router or between a pair
of routers or such like ?  It does kind of sound like it is doing an
IP-layer function but partly like an ALG.  Middlebox of some sort
either way.

Ran
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