Subject: the VoIP Paradox

From: S Woodside <[email-masked]>
Date: Sun, 31 Aug 2003 02:04:06 -0400

http://simonwoodside.com/projects/ict/voip_paradox.html

   The Voice over IP paradox

       Simon Woodside

*Abstract*

Voice over IP is paradoxically both internet and telephony at the same
time. This article presents the paradox, and associated arguments.

------------------------------------------------------------------------

*Table of Contents*

VoIP paradox and explanation
Regulation of VoIP
In the Real World
Conclusion

     VoIP paradox and explanation

In a nutshell:

     Voice over IP is paradoxically both internet and telephony at the
     same time.

To understand this paradox we must adventure into the wild lands of
reliability and availability.

internet

     The public internet. Availability on the public internet is /best
     effort/ which means that other factors (such as price and bandwidth)
     can be more important than availability.

telephony

     The public and private branch exchanges of the telephone network.
     Availability in telephony is counted as /five nines/. So, 99.999% of
     the time when you pick up the phone you get a dialtone. That's all
     but five minutes per year.

So what is this /availability/ beast?

availability

     Given a random point in time, how likely it is that the system is
     working at that moment.

The arbitrary point in time could of course be during an emergency. Will
VoIP work during an emergency? Here we run headlong into the paradox!
Because the internet is most emphatically not available in an emergency,
while telephony must be in order to have a functioning emergency 
response.

     Regulation of VoIP

It is easy to restate the VoIP Paradox in terms of regulation (by the
government). (Consider emergency use.)

     a. VoIP is telephony and should be regulated.

     b. VoIP is internet and should not be regulated.

Both seemingly reasonable statements, given the nature of regulation on
telephone systems and the public internet these days.

     In the Real World

In the real world there are two types of implementations of VoIP that
reflect the paradox. First are the telephony-style implementations where
the phones come out and the VoIP goes in. Opposed are the internet-style
voice chat systems such as Microsoft NetMeeting, GnomeMeeting, and iChat
which are usually supplemental to an existing phone.

     Conclusion

There is no conclusion. The situation is playing out in real time.

--
simonwoodside.com -- openict.net -- 99% Devil, 1% Angel

---

From: grenville armitage <[email-masked]>
Date: Tue, 02 Sep 2003 11:21:06 +0200

S Woodside wrote:
	[..]
> time. This article presents the paradox, and associated arguments.

Your paradox seems artificial. "IP Telephony" is both internet and telephony,
but Voice over IP makes no claims (except in sloppy reporting) to be
telephony. Unless, that is, you consider commerical 2-way radios, CB radios,
intercoms and tin-cans-and-string to also be telephony by virtue of involving
transport of voice.

cheers,
gja

---

From: S Woodside <[email-masked]>
Date: Tue, 2 Sep 2003 09:56:59 -0400

> intercoms and tin-cans-and-string to also be telephony by virtue of 

Sloppy reporting? Which way would you like it...

"The focus of the IP Telephony (iptel) group is on the problems related
to naming and routing for Voice over IP (VoIP) protocols."
     http://www.ietf.org/html.charters/iptel-charter.html

Period. If they meant otherwise they would have said "related to naming 
and routing for telephony-related VoIP protocol usage". There is no 
attempt on the IPtel WG page to distinguish between VoIP uses on the 
public internet vs. other IP networks.

(You say "VoIP makes no claims to be telephony" but the SIP page 
differs:

"SIP, the Session Initiation Protocol, is a signaling protocol for 
Internet conferencing, telephony, presence, events notification and 
instant messaging."
     http://www.cs.columbia.edu/sip/
)

simon

---

From: [email-masked]
Date: Tue, 02 Sep 2003 10:44:11 -0400

>      http://www.cs.columbia.edu/sip/

So what you're saying is that everything that includes a gasoline engine
is a truck, even though cars, lawnmowers, and some ultralight planes
use it as well.

---

From: Harald Tveit Alvestrand <[email-masked]>
Date: Tue, 02 Sep 2003 08:10:18 -0700

[note - the 2 sets of expectations for VoIP rollouts is a very true 
obsevation. however....]

paradox? what paradox?

the fact that VoIP has two largely orthogonal qualities at the same time is 
not a cause for calling it paradoxical; only if they have to have two 
incompatible values of the same metric should the "P" word be applicable.

>      can be more important than availability.

"best effort" means that you get no better service than what you pay for.
Why shouldn't that achieve five nines?

>      but five minutes per year.

and one has to carefully tune the measures of "availability" to achieve 
that figure.

for instance (personal experience from Norway, mostly):
- pabx availability is dependent on the janitor not tripping over the power 
cord, and not measured
- a cell phone that is out of range is not counted (of course!)
- a subscriber line that is down is not counted until the time the 
subscriber reports the error.
- "acts of God" like fires in telephone exchanges (and even some "backhoe 
fade" cable faults) are not counted.
- if you try to call Liberia, all bets are off.

in practice, five nines is a shared illusion between the operator and the 
regulator.

Conclusion:

statistics always lie.
what exists, exists.
paradox is in the mind of the beholder.

---

From: S Woodside <[email-masked]>
Date: Tue, 2 Sep 2003 12:16:25 -0400

On Tuesday, September 2, 2003, at 11:10 AM, Harald Tveit Alvestrand 
wrote:

> the fact that VoIP has two largely orthogonal qualities at the same 
> time is not a cause for calling it paradoxical; only if they have to 
> have two incompatible values of the same metric should the "P" word be 
> applicable.

the metric is availability.

> Why shouldn't that achieve five nines?

Because it's local-network reliability only. The remote party and 
everyone in between would also need to pay for the higher availability 
as well to ensure edge-to-edge availability at five nines. My 
assumption is that is a non-goal of the "best effort" network.

> and one has to carefully tune the measures of "availability" to 
> achieve that figure.
>
> - pabx availability is dependent on the janitor not tripping over the 
> power cord, and not measured
> - "acts of God" like fires in telephone exchanges (and even some 
> "backhoe fade" cable faults) are not counted.
> in practice, five nines is a shared illusion between the operator and 
> the regulator.

Perhaps, perhaps not. I live in Ontario Canada and in the recent 
blackout, my phone kept working. It was as one might say an "object 
lesson" in the difference between best-effort and five nines.

simon

---

From: Scott Bradner <[email-masked]>
Date: Tue, 2 Sep 2003 14:22:03 -0400 (EDT)

> blackout, my phone kept working.

i.e., you did not have a ISDN or wireless phone

Scott

---

From: Michael Richardson <[email-masked]>
Date: Tue, 02 Sep 2003 15:25:41 -0400

-----BEGIN PGP SIGNED MESSAGE-----

>>>>> "Scott" == Scott Bradner <[email-masked]> writes:

    Scott> i.e., you did not have a ISDN or wireless phone

  Wired POTS phones did not continue working for many Bell Canada
subscribers. It isn't clear why, but many rural folks were without 911
service for 18 to 20 hours. I expect that that the failsafe systems were
not tested recently enough.

]      Out and about in Ottawa.    hmmm... beer.                |  firewalls  [
]   Michael Richardson, Sandelman Software Works, Ottawa, ON    |net architect[
] [email-masked] http://www.sandelman.ottawa.on.ca/ |device driver[
] panic("Just another Debian/notebook using, kernel hacking, security guy");  [

---

From: S Woodside <[email-masked]>
Date: Tue, 2 Sep 2003 15:44:39 -0400

> i.e., you did not have a ISDN or wireless phone

Yes we still have an old-fashioned no frills basic telephone in the 
house. I also have a portable 900 MHz digital phone (dead), a DSL 
connection (dead, at a minimum because the modem had no power), a 
laptop (which worked long enough for me not to notice the outage at 
first, until I went to connect to the internet, when I noticed the net 
was down, when I noticed my 802.11 was down, when I noticed my DSL 
modem was down, when I noticed the power was out ...)

To get news I dug out an old walkman the batteries were still working. 
Also my cell phone DID work (with Bell Mobility in Canada).

It is my impression that wireless local loop systems (WLL) for 
telephony include backup batteries in subscriber units as well. That 
might be due to either regulation or expectations or both.

simon

--
      anti-spam: do not post this address publicly
www.simonwoodside.com -- 99% Devil, 1% Angel

---

From: Scott Bradner <[email-masked]>
Date: Tue, 2 Sep 2003 15:46:49 -0400 (EDT)

> telephony include backup batteries in subscriber units as well. That 

I was referring to cordless phones - not cel phones

they also die when the power goes out, for some reason some people
do not expect that to be the case

Scott

---

From: Kireeti Kompella <[email-masked]>
Date: Tue, 2 Sep 2003 13:36:18 -0700 (PDT)

> do not expect that to be the case

which is why I still have _one_ corded phone, plugged into the power
outlet sometimes referred to as a phone line.

Kireeti.

---

From: Michael Richardson <[email-masked]>
Date: Tue, 02 Sep 2003 17:20:43 -0400

-----BEGIN PGP SIGNED MESSAGE-----

>>>>> "S" == S Woodside <[email-masked]> writes:
    S> Yes we still have an old-fashioned no frills basic telephone in the 
    S> house. I also have a portable 900 MHz digital phone (dead), a DSL 
    S> connection (dead, at a minimum because the modem had no power), a 

  I had UPS backup for laptop, switch, firewall and DSL.
  The LINK light on the DSL was on. There was nobody home.

  My ISP happened to call me on a DNS question, and reported that their
generator worked fine. And that things upstream were just fine. In fact, very
fast, since most of the traffic was gone.
  What was dead? The Bell Nexxia ATM network connecting us. I.e. my layer 2. 
  So, we aren't that far away.

  Power-Over-Ethernet would be great... if I could get ethernet to my office.

---

From: Iljitsch van Beijnum <[email-masked]>
Date: Tue, 2 Sep 2003 23:49:50 +0200

> i.e., you did not have a ISDN or wireless phone

The telco can provide power over the ISDN line for a single device on 
the ISDN bus if that device can operate under the necessary 
restrictions. (This power is so limited that it takes several seconds 
for the phone to become operational in emergency power mode.)

But what good does it do to have DC on your phone line if the network 
is utterly congested? With IP the service level degrades more 
gracefully. (Although this wouldn't necessarily work well for _voice_ 
over IP.)

---

From: Masataka Ohta <[email-masked]>
Date: Wed, 3 Sep 2003 07:23:34 +0859 ()

Simon;

> time. This article presents the paradox, and associated arguments.

There is no paradox. The internet carries information.

You should, at least, distinguish VoIP as a telephone network
and the Internet telephony.

In Japan, TAs to connect the Internet and POTS telephone devices
are rapidly replacing the telephone network including VoIP ones.

>      b. VoIP is internet and should not be regulated.

Why, do you think, the Internet without voice should not be regulated?

It is.

Paradoxical reguration on voice in US is a US local issue.

						Masataka Ohta

---

From: Richard Shockey <[email-masked]>
Date: Tue, 02 Sep 2003 20:06:30 -0400

At 11:49 PM 9/2/2003 +0200, Iljitsch van Beijnum wrote:

>But what good does it do to have DC on your phone line if the network is 
>utterly congested? With IP the service level degrades more gracefully. 
>(Although this wouldn't necessarily work well for _voice_ over IP.)

I'm sorry but obviously you've never used SIP on a connection with greater 
thatn 128K of upstream bandwith or properly configured ethernet network 
with priority bitting.

my sincerest sympathies..

Richard Shockey, Senior Manager, Strategic Technology Initiatives
NeuStar Inc.
46000 Center Oak Plaza  -   Sterling, VA  20166
sip:rshockey(at)iptel.org   ENUM +87810-13313-31331
PSTN Office +1 571.434.5651 PSTN Mobile: +1 703.593.2683,  Fax: +1 815.333.1237
<mailto:richard(at)shockey.us> or <mailto:richard.shockey(at)neustar.biz>
<http://www.neustar.biz> ; <http://www.enum.org>
<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<

---

From: [email-masked]
Date: Tue, 02 Sep 2003 16:12:06 -0700 (PDT)

> in practice, five nines is a shared illusion between the operator and the

It's an illusion in my experience as well. Growing up in Oklahoma, long
distance calls (that is, any call not to one of the 700 other people that lived
in the town of Perkins) could be direct dialed but then an operator had to come
on the line to ask for the caller's number (no, I'm not fooling about this). No
number gathered meant no call got completed. The failure rate for this setup
was, for whatever reason, non-negligable. I'd estimate its reliability at two
9s at most. The fact that the initial dial tone was always present didn't
translate into a reliable phone service, and worse, you could waste a
considerable amount of time before it was evident the call had failed.

Once I moved to Los Angeles I spent some time working as a technical director.
One of the things technical directors do is make phone calls -- lots and lots
and lots of phone calls. Unfortunately the PABX I was "behind" had an interop
problem with the telco with lots of finger pointing on either side as to  where
the fault was. The result was a 25% call success rate. The failure modes were
also many and varied, which added to the fun. (I used to keep a tally on a pad
next to the phone, so I had actual data to back up this figure.)

These days things are much better. But phone problems are nevertheless quite
common around here. On several occasions my DSL connection has worked fine but
there was no dial tone on the phone line. (In one case one of the conductors
was actually broken. The DSL circuit managed to work, albeit with a high error
rate, over a single piece of copper. POTS service did not. Ain't capacitive
coupling grand?) And in talking with other people who live around here, I find
that my experiences are hardly unique. If anything, I have had fewer problems
than most.

As far as power failures go, I have full battery backup at home, and when the
power goes my experience has been that both POTS and DSL have continued to
operate, but call completion rates tend to go way down.

> statistics always lie.

Either that or an awful lot of people must be experiencing truly spectacular
phone service to balances things out.

				Ned

P.S. Nothing prevents you from having battery backup on cordless phones. That's
what I do, for the important ones at least.

---

From: Michael Richardson <[email-masked]>
Date: Tue, 02 Sep 2003 21:11:56 -0400

Last IETF in Minneapolis, I couldn't call my home.
Why? new exchange in Ottawa. 715. Minneapolis thinks that is an area
code... Wisconsin. No operator could understand this concept or problem, and
even 1800 calling card access seemed screwed. I SMS'ed or IRC'ed my wife
to say I was going to my room, and she called me.

Five "9"s indeed :-)

---

From: S Woodside <[email-masked]>
Date: Tue, 2 Sep 2003 21:10:48 -0400

> and the Internet telephony.

There is no "internet telephony"... there is "IP telephony" which is 
not running on the public internet. There is also VoIP on the public 
internet which I like to call "Voice Chat".

> are rapidly replacing the telephone network including VoIP ones.

... do they provide PSTN-level availability? in an emergency / power 
failure?

> Why, do you think, the Internet without voice should not be regulated?

It is? Not to my knowledge, and especially, not on the issue of 
availability and reliability.

> Paradoxical reguration on voice in US is a US local issue.

Please cite a document, I don't find any japanese regulation that makes 
it any different there...

simon

---

From: S Woodside <[email-masked]>
Date: Tue, 2 Sep 2003 21:38:21 -0400

> to say I was going to my room, and she called me.

wandering a little off topic...

My experience is the phone system in USA is far inferior to in Canada.  
In Silicon Valley of all places, I would get max 28.8 on a noisy line  
with a 56K modem, and get DSL? joking... There's a huge debate about  
cell phones failing in the states in the powerout but my cell phone in  
Toronto worked A-OK.

"All four Canadian cellphone service providers reported sporadic  
connections during the power outage, but defended the overall wireless  
performance."
      
http://www.canada.com/technology/story.html?id=6B2CB9DE-F15C-46A1-BCF2- 
04888F2098AC

"All four large mobile players, a group that includes Bell Canada and  
Microcell Telecommunications Inc., suffered problems during the power  
outage. AT THE WORST [emphasis mine], it is estimated that between  
one-fifth and one-quarter of mobile networks did not work."
      
http://www.globetechnology.com/servlet/story/RTGAM.20030821.ucell0821/ 
BNStory/Technology/

compare: NY City...
"cell phone service got worse, not better, as the blackout continued,  
when thousands of cell phone towers and transmitters lost power because  
their battery backups only lasted from two to six hours. Cell phone  
companies didn't have enough generators to recharge the batteries and  
found that recharging was an hours-long process for each of the  
thousands of cell phone transmitters in New York."
     http://www.cellular-news.com/story/9590.shtml

simon

---

From: Masataka Ohta <[email-masked]>
Date: Wed, 3 Sep 2003 21:54:02 +0859 ()

Simon;

> There is no "internet telephony"...

See my paper "Simple Internet Phone" presented at INET2000.

	http://www.isoc.org/inet2000/cdproceedings/4a/4a_3.htm

It, for example, says:

	However, it is obvious that the telephone network will be
	replaced by the Internet, and will eventually disappear.

> there is "IP telephony" which is 

Apparently, you don't recognize the current situation, which I
foresaw several years ago.

Voice chat, of course, is no internet telephony.

> it any different there...

Japanese telecommunication laws (available at
http://law.e-gov.go.jp/cgi-bin/idxsearch.cgi) does not distinguish
telephony or voice something special and the requirement on
providers is same, though detailed requirements varies.

> ... do they provide PSTN-level availability?

In theory, yes.

In practice, there is no such thing as PSTN-level availability.

> in an emergency / power 

In emergency, best effort network works better than circuit
swithced one, of course.

As for power, have you ever used ISDN with TAs?

						Masataka Ohta

---

From: Michael Richardson <[email-masked]>
Date: Wed, 03 Sep 2003 14:21:46 -0400

I was downtown Ottawa on the Friday, eating at a restaurant that had power,
since we had none at home. (at least, when we arrived they had power...)

What I noticed is that my GSM (Fido/Microcell) had very poor reception,
and I frequently didn't get a signal. My conclusion - they don't have all
of the transponders on generator backup, so they have less capacity during
a blackout.

Repeating this design for IP telephone would not be a good idea :-)

---

From: Michael Thomas <[email-masked]>
Date: Wed, 3 Sep 2003 11:48:50 -0700 (PDT)

> Repeating this design for IP telephone would not be a good idea :-)

Actually, we're about to repeat it in a much worse
way. John pointed out that IP routed around
problems during these outages, but I don't think
that we should too glib about how real life those
tests really were wrt VoIP: voip traffic is still
a tiny fraction of TDM where it counts (ie, at
congestion points and especially at the slow
edges).

I despair that it will not be till way too late
that we discover -- unsurprisingly -- that flash
crowds and IP brownouts are not only possible, but
to be expected. More's the pity that we have both
the standards and the deployed code (RSVP) to largely
avoid this disaster in the making. 

I think that there's some belief that this is a
technical problem with RSVP (too heavy, too
whatever), but I think that's a gloss: signaled
QoS is just plain hard and heavy and slow and all
kinds of other unpleasant things by its very
nature. No technical solution is going to make it
into diffserv or best effort. So we're going to
have a disaster and then Congress will do what the
industry couldn't...

		Mike

---

From: Dean Anderson <[email-masked]>
Date: Wed, 3 Sep 2003 15:30:30 -0400 (EDT)

> avoid this disaster in the making.

This overstates things by quite a bit. RSVP is not up to the task in a
very significant way. Not only is RSVP not scalable (in similar ways that
affect Multicast), but even assuming those problems were solved, which is
possible, even given an ideal labatory setting, RSVP does't solve the
problem,

RSVP is not "too heavy".  It doesn't work.  Not even a little bit.
Assuming every router in the path played RSVP, there are two show-stopper
problems: It can't detect a network failure, and the path might change for
other reasons, so traffic is flowing places where resources weren't
reserved.

For RSVP to work, every router, end to end has to use it.  If ISPs used
RSVP between ISPs, some provider somewhere else would be able to really
screw up your network. (Just like multicast routing)

RSVP was a good try, but not a production solution.

---

From: grenville armitage <[email-masked]>
Date: Thu, 04 Sep 2003 09:36:11 +0200

S Woodside wrote:
	[..]
> There is no

Considering that their focus is, as you observed, on the naming and
routing aspect I consider this an understandable simplification. But
it is, of course, merely a simplification and not a paradox.

>      http://www.cs.columbia.edu/sip/

"SIP" != "VoIP" in any way meaningful to our discussion of your "paradox".

cheers,
gja