Subject: RE: [Ieprep] Measurement of Internet Congestion

From: "Nguyen, An" <[email-masked]>
Date: Tue, 12 Nov 2002 15:42:07 -0500

-----Original Message-----
From: Bill Woodcock [mailto:[email-masked]]
Sent: Tuesday, November 12, 2002 12:57 PM
To: Nguyen, An
Cc: RJ Atkinson; [email-masked]
Subject: RE: [Ieprep] Measurement of Internet Congestion

      On Tue, 12 Nov 2002, Nguyen, An wrote:
    > In short, G.711 is G.711 regardless of the transport layer.

Yes, of course.  However, on the PSTN, that's switch-to-switch.  Several
miles of bridge-tapped 28-gauge junk away from each user, in nearly the
best case.  In an ideal world, you'd have ISDN desk-sets in front of every
POTS user, but I don't hear anyone suggesting that.

    > Let me tell the experience with the VoiceIP deployment...
    > None of [the RFP-respondents] wanted to guarantee end-to-end High
    > Availability of 99.999

That's not deployment experience, that's you talking to a salesperson.
Which has exactly nothing to do with networks or operational reality, or
voice quality.

No, actually we had several conference calls with the network design and
engineering folks on the issue. And they all said the same things. They also
said in order to boost 3 nines to four nines we have to add a parallel
(access) circuit to each of the endpoint, which is not economical at all to
us. And we only get 99.99 if we chose to go down that route. 

    > They said the max they could provide was 99.9

Okay, hypothetically, let's say they really are as bad as the worst that
they were actually willing to guarantee in writing.  If they lose one
packet in a thousand, do you really think that VoIP will fall apart at the
seams?  Do you think that'll even have an effect which could be measured
in the lab?  Much less noticed by happy users?  VoIP seems to me to work
pretty darned well at 96%-97%. 

     99.9 means 8.76 hrs/yr in down time and 99.99 means 52.56 min/yr.
     Three nines could be a big problem for emergency personnel specially
when they are in
     a disaster area and want to communicate with their counterparts. These
three nines are  
     given with the assumption that there is absolutely nothing wrong with
the networks.

    > ATM for transport

Ouch.  Yeah, well, if you actually did build the network and had problems,
there's your source.  Fortunately the Internet hasn't used any significant
quantity of ATM since it was deprecated a few years ago.

     It's not pure ATM as you thought. It's actually IP over ATM AAL5.

    > NCS has to deal with many ISPs to address this issue
    > in order to get ubiquitous.

Yes, tens of thousands.  I'm still having a bit of a hard time with the
notion that NCS really wants to enter into and manage SLA contracts with
tens of thousands of ISPs.

     Our goal is to be ubiquitous (as technically and financially as
possible). We hope in dealing with large ISPs they will give us better
coverage.

                                -Bill

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From: Bill Woodcock <[email-masked]>
Date: Tue, 12 Nov 2002 16:40:49 -0800 (PST)

On Tue, 12 Nov 2002, Nguyen, An wrote:
    > engineering folks on the issue. And they all said the same things.

Correct.  That's _talk_, not _deployment experience_.  We're in violent
agreement, I think.

    >> If they lose one packet in a thousand, do you really think that
    >> VoIP will fall apart at the seams?

Okay, that's if taken together, rather than evenly distributed.  In point
of fact, you'll have a little bit of both.  But since you suggest it, what
are the odds of an emergency occurring at a specific site within any
arbitrary single 9-hour window, each year?  Since you say that it wasn't
worth the cost of a second local loop to reduce that to one hour,
presumably the odds are already awfully low.

    > It's not pure ATM as you thought. It's actually IP over ATM AAL5.

Correct...  Voice directly over ATM isn't a bad thing, particularly, if
you know how to run an ATM network...  It's when you try to run data over
ATM that it doesn't particularly work.  And of course, it's irrelevant
now, since there haven't been ATM products that could keep up with
production network speeds in the last few years.  But this is taking
the conversation off into the weeds.

    >> I'm still having a bit of a hard time with the notion that NCS
    >> really wants to enter into and manage SLA contracts with tens of
    >> thousands of ISPs.

Yes, slightly, but not significantly.  That's one of the major ways in
which the Internet differs from the PSTN.  And it's something you guys
really need to analyze, in order to determine whether you're asking for a
product that you're not going to be able to afford to buy.

                                -Bill