I don't think the proper
argument is about credentials. The proper argument is about design and
architecture. Bennett keeps trying (on this and other lists) to
impute motivations to people, to make claims about their deviousness,
etc.
Vint's original point is about putting the user in control of priority,
since the users (and the services the user uses on the other side of
the network) know what's important and what's not. Reading tea leaves
by inspecting the contents of packets for clues is a piss-poor way to
judge what the user wants. Let the user say "this stream of packets is
life and death" even if it looks like a music download, and this is
"not terribly important" even if it looks like a telephone call.
It's not up to the ISP to decide for the user what services are
important and what protocols are important.
Trying to claim that Vint's view on this is a "fringe" idea is just
nonsensical.
On 11/02/2009 06:34 PM, George Ou wrote:
Vint Cerf says: “I don't understand why
a low
bandwidth application is necessarily higher priority than a high
bandwidth one
for example.”
With
all due respect to your credentials, it seems like you’re
taking end-to-end too literally and even more so than most of the
authors of
that paper.
I
think you have a fringe position that a lot of great engineers
and academics would vehemently disagree with. In fact it violates the
most fundamental concepts of fairness that a low bandwidth and non
jitter-inducing applications such as VoIP or online gaming (sub 100
Kbps)
shouldn’t have their packets forwarded first. Despite the lower
priority state, the high bandwidth applications WILL STILL receive the
highest
average bandwidth application and the overall file transfer speed of a
P2P
application would be unchanged. So the P2P application will experience
zero degradation (I’d argue it would improve in performance because
fewer
people would shut P2P off if it is less toxic) and VoIP or online
gaming would
experience close to zero jitter. The fact that we’re doing round
robin on the transmit queue is fundamentally more fair than a First In
First
Out (FIFO) system.
The
system if implemented very accurately if it measures
protocols based on data patterns and not just simple port number
identification, it would prevent protocol masquerading abuse and it
would avoid
misclassifying some “P2P” protocols such as Skype as a “background”
application.
Vint Cerf says: “Nor do I see that low
duration
should necessarily have precedence over high duration (regardless of
bandwidth).”
I
have made it clear in figure
4 of my article on why this makes sense (concept thanks to Bob
Briscoe).
Assuming that both applications are bursty e.g., they take whatever
bandwidth
the network can feed them, the lower duration application with much
smaller
transfers should always get higher priority. Again, this would result
in
no performance declination for a large bulk transfer since the low
duration application
would simply get out of the way sooner. The difference is that the low
duration application (web surfing) would run MUCH better than before
which would
allow users to leave their P2P or any other file transfer application
running
24x7 without fear of degrading their network. The result is that web
browsing and other low duration applications run much better and P2P
would run
faster due to the increase in available seeders.
Vint Cerf says: “I can readily
understand, for
example, the shaping of the overall traffic envelope for a given user,
based on
the service class to which that user belongs (here I am thinking of
maximum
burst capacity as a measure of "class").”
As
I’ve mentioned before, you are severely limiting the
tools available to engineers and services by suggesting that the only
permissible differentiator between classes should be maximum
bandwidth.
Moreover, there’s no reason that users shouldn’t be allowed to
purchase different levels of fractional ownership (in the form of usage
caps)
and be permitted to purchase multiple usage caps e.g., one for
low/medium/high
priority where the lower priorities will have the most generous usage
caps
(possibly no caps).
George
Ou
From: Vint
Cerf
[mailto:vint@google.com]
Sent: Monday, November 02, 2009 3:06 PM
To: George Ou
Cc: 'David P. Reed'; 'NNSquad'; 'Lauren Weinstein'; 'Richard
Bennett'
Subject: Re: [ NNSquad ] Re: [IP] BitTorrent uTorrent 2.0 uTP
will
self-throttle to protect networks
george,
Yes I do have problems with the default choices
as I am not
sure it is clear that these defaults make sense. I don't understand why
a low
bandwidth application is necessarily higher priority than a high
bandwidth one
for example. Nor do I see that low duration should necessarily have
precedence
over high duration (regardless of bandwidth). These choices seem bereft
of
clear rationale. I think one area that may drive our differences is
whether there is an overall workable way to allocate capacity among
users,
independent of priority within that capacity. I can readily understand,
for
example, the shaping of the overall traffic envelope for a given user,
based on
the service class to which that user belongs (here I am thinking of
maximum
burst capacity as a measure of "class"). In times of congestion, I
think I would be inclined to argue for user prioritization within a
"fair
share" of the available capacity for that user.
On Nov 2, 2009, at 5:58 PM, George Ou wrote:
I
understand that Google and others like to tout “user
preference prioritization”, but you haven’t addressed some of the
key limitations to that system. I am fine with user-labeled priority
so
long as it operates with reasonable priority quotas and budgets, but
what do
you do about the vast majority of users and applications that fail to
label
accurately or fail to label at all? So my question to you is this:
· Do
you have a problem with a
default priority mechanism - one that would cede control to user or
application
preference so long as it is within quota – that is implemented by the
ISP
which always gives higher priority to low bandwidth applications over
high
bandwidth applications, and gives priority to low duration applications
over
high duration applications? Do you have a problem with this type of
good
discrimination?
· If
you do have a problem with
a default ISP priority, please explain your reasoning. Is the
objection
based on a concern that a default prioritization scheme would
inaccurately
classify information (even though we can classify based on packet
patterns
rather than simple port identification), or do you have a philosophical
problem
with it? And if so, how would this be any different Comcast’s
“Fair Share” system which prioritizes low bandwidth users (average
measured over 15 minutes) over high bandwidth users which the FCC
reviewed and
considers fair?
From: Vint
Cerf
[mailto:vint@google.com]
Sent: Monday,
November 02,
2009 2:33 PM
To: George Ou
Cc: 'David P.
Reed';
'NNSquad'; 'Lauren Weinstein'
Subject: Re: [
NNSquad ]
Re: [IP] BitTorrent uTorrent 2.0 uTP will self-throttle to protect
networks
This discussion
suggests that
users should have something to say about the priority of packet flows
WITHIN
the capacity they are paying for (capital letters just in lieu of
italics; I am
not shouting). If the access ISP can do traffic shaping to keep users
within
their pro-rata envelopes and also respond to user-specified priority, I
would
think we would be moving toward a balance that seems useful.
On Nov 2, 2009, at
1:54 PM, George
Ou wrote:
I’ve published my
results
here.
Dr. Reed. Your use
of the
words “rhetoric” and “tricks” aren’t very useful
to this discussion, and I would take issue with your comments.
1. BitTorrent
still hogs
over 90% of my broadband connection over HTTP. This has significant
ramifications beyond just real-time applications like VoIP and online
gaming.
2. You
shouldn’t be so
quick to discount VoIP and online gamers. A very large number of
BitTorrent (or any P2P app) users also do online gaming and VoIP, and
they’re forced to shut down their P2P application when the use VoIP or
game and that actually hurts the P2P upload and download throughput for
the
entire P2P community since there are fewer seeders.
3. Don’t
conflate wireless
with wired broadband. Just because 150 ms ping for wireless is best
case
doesn’t make 70 ms additional on a wired network bearable for online
gaming. Maybe you’re different, but I don’t know any gamer
that will put up with an additional 70 ms if they can help it. I
thought
it would be tolerable for VoIP, but my Lingo VoIP phone service drops a
significant amount of audio even when I merely upload with BitTorrent.
I find the word
games/rhetorical
tricks that Ou and Bennett use fascinating. We'll see whether Farber
posts my response below.
George Ou wrote:
Subject:
RE: [ NNSquad ] BitTorrent uTorrent 2.0 uTP will self-throttle to
protect networks
Too bad nobody ever bothered to test if these claims actually hold water
before repeating them endlessly. I just tested uTorrent version 2 build
16850 today and it still grabs all the bandwidth and jacks up the ping
to
unbearable levels for online gaming and VoIP. It certainly does NOT
protect
my network.
I will do
some testing myself, because I am curious about the
mechanism in uTorrent 2.0. I do note that "unbearable levels for
online gaming and VoIP" is an interesting statement.
If true that means that ping times might be 100 msec or more. Now,
since I have been recently measuring ping times on networks where there
are no
"uTorrent" or other P2P services running, I can tell you that on a
variety of commercial providers, 150 msec. ping times are common - and
on ATT
3G in several cities, there are stable ping times that can be measured
that are
on the order of 2000-5000 msec.
So the "data" presented by Mr. Ou represents a very, very interesting
choice of phrase. Say that it is "unbearable" for two of
the most sensitive-to-latency applications (only).
I would, myself, stick to scientific measurements: how many
milliseconds? Clearly he has measured that data. But I
presume the hope of a talented columnist is to get the word
"unbearable" to stick in the mind, and leave the "bumper
sticker" impression without the qualifying information.
Rhetorical trickery? You be the judge. I'm gonna report
numbers.
|