Subject: Re: [Ieprep] RE:MLPPoIP - Preemption of low priority calls

From: [email-masked]
Date: Wed, 26 Nov 2003 15:17:56 EST

In a message dated 11/26/2003 12:04:20 PM Eastern Standard Time, 
[email-masked] writes:

> Please refer to the GSCR for mandatory test criteria to this which every 
> vendor MUST comply with in order to be certified  by DISA.
> 
> MLEF is contradictory to the GSCR - one has to give.
> 

The current GSCR was written for circuit mode. Unless we get it changed, it 
will apply to packet mode (even when it doesn't always make sense). This is one 
of the areas we are trying to change, so it correctly takes into account the 
advantages of using packet.

I see needing some qualifying statement that an MOS=4.0 is not required in 
the case of the resources for low precedence calls being preempted for high 
precedence calls. It analogous to the requirements for premature disconnect. You 
can't fail the requirement because preemption causes disconnects.

In any case, ignoring priority calls for a moment, how would this criteria be 
met, that is, limiting the number of packet flows that get attempted through 
a single, limited resource so that there is no congestion or packet loss?

Mike

---

From: Rex Buddenberg <[email-masked]>
Date: 26 Nov 2003 13:46:55 -0800

On Wed, 2003-11-26 at 12:17, [email-masked] wrote:
...
> 
> The current GSCR was written for circuit mode. Unless we get it
> changed, it will apply to packet mode (even when it doesn't always
> make sense). This is one of the areas we are trying to change, so it
> correctly takes into account the advantages of using packet. 
...

This whole conversation appears to be predicated on some tacit and false
assumptions.

The principal assumption seems to be that the entire capacity of a hop
is taken up with VOICE conversations so that the solution to
oversubscription is to shed some of those VOICE conversations.  

If you come to the conversation with a bellhead mentality, then we can
probably read up on Erlangs and reach much the same conclusion that the
circuit switch world reached years ago.

If you have a priority voice conversation and experience congestion, it
would seem to me that we would want to bump something other than other
voice conversations:
	- anything file transfer (incl e-mail enclosures) with .ppt in the file
label.  The content:bit-bloat ratio there is terrible to the extent that
I'm calling powerpoint a virus these days.
	- cut back a VTC to voice only.  The psychologists tell us that a
talking-head VTC has visual cues that we use for about 5-10 minutes;
after that we might as well turn the video off and just leave the
audio.  The problem here is that we can't know by looking at port
numbers whether someone has turned the camera around and is sharing view
of a crime scene
	- filter out any ftp-based operating system installs (they can wait). 
Only picking on this example because I did it this morning.
	What we have to be careful not to do is filter out things that are
higher priority than the priority voice conversation.  LSAs (router link
state announcements, necessary to keep the network converged and
functioning) is one example.  

-- 
b

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From: [email-masked] (Scott Bradner)
Date: Wed, 26 Nov 2003 17:16:27 -0500 (EST)

>         - anything file transfer (incl e-mail enclosures) with .ppt in the file

kinda tricky for a router to figure out if the data stream is a ppt file

Scott