[e2e] [SPAM] opening multiple TCP connections getting popular
Jon.Crowcroft at cl.cam.ac.uk
Wed Aug 29 11:54:05 PDT 2007
I dont really see the new problem, or any problem at all -
every day I have an SSH session, a remote file system mounted and two different browsers
- so i have lots of TCP connections mostly from one site to another site, albeit
to possibly slightly different machnes (although often all via the ssh tunnel, so
via th e same end point)
the point is that, like topological DDoS attacks, the crucial point is what share
ot the bottleneck piint in the net I get - since in my caser the bottleneck is a
20Mbps DSL line I pay for, i see it is fair, and agnostic of me t, to run as many
or few TCP conenctions as I choose over my (I bought it) dsl line, and I see the
access ISPs right to choke the line if they have a problem - it is way below the
IP or TCP level and is to do with traffic engineering in general how thee trade
off between my use of capacity and the service provider's offering of capacity
are matched - tcp is not about resource allocation, it is about congestion
control which is about avoiding probklems when they arise, not about normal
operational cake-slicing imho.
bob: you are suffering from what I might call the TCP-delusion, (with apologies
to richard dawkings)
In missive <46D5B665.6090800 at reed.com>, "David P. Reed" typed:
>>It's worth pointing out that this is nothing new. So-called
>>download-accelerators that do exactly that have been around for at least
>>5 years now, and are extensively used on Windows platforms, because
>>they work as advertised. I think the one I used to use on Windows was
>>called "Lightning Download" and it was freeware.
>>But a deeper question is this: if I want a movie each day, and my daily
>>average rate of consumption is not going to change because I can't watch
>>movies faster than my eyeballs work, why is this going to be a big
>>problem? Is there any evidence of people downloading movies that they
>>The mitzvah gained from shorter latencies allows other people to
>>download at their convenience with out me competing with them.
>>In fact, isn't dragging one's download out just maximizing all the users
>>Maybe the sky isn't falling?
>>Bob Briscoe wrote:
>>> e2e-interest folks,
>>> This product is being very aggressively marketed:
>>> It opens 10 HTTP/TCP connections to accelerate video downloads -
>>> essentially using the well-known broken feature of TCP (see the I-D
>>> below) to enable one user to compete more aggressively for the same
>>> bandwidth against other users. But it flies below the limit of 10
>>> concurrent half open connections added to Windows XP SP2 - claimed to
>>> be added to slow down worms but also limiting p2p filesharing clients.
>>> Amazingly, these guys are approaching ISPs to re-sell this product -
>>> so their customers will just be competing more aggressively with each
>>> other and largely end up back where they started. It's worth reading
>>> the Business Week article linked off the above page to see just how
>>> convincingly this is being marketed - They fooled the technology
>>> assessment people in at least one large ISP (mentioning no names).
>>> If you're tempted to poke fun at all these people because they clearly
>>> don't understand, I actually think we should be chastened ourselves.
>>> Why shouldn't app-layer people expect the transport layer to correctly
>>> handle fairness?
>>> To quote the Internet Draft "Flow Rate Fairness: Dismantling a Religion"
>>> "...flow rate fairness isn't even capable of reasoning about questions
>>> like, "How many flows is it fair to start between two endpoints? ...
>>> ...there will certainly be no solution until the networking community
>>> gets its head out of the sand and understands how unrealistic its view
>>> is; and how important this issue is--a conflict between the vested
>>> interests of real businesses and real people."
>>> King Cnut commanded the tide not to wash over him sitting on his
>>> throne on the English beach, but at least when the experiment failed
>>> he humbly accepted he was subject to greater powers, never wearing his
>>> crown again. I'm worrying away at the IETF to work on a proper
>>> solution to the TCP-fairness problem, rather than merely issuing the
>>> decree that RFC2616 HTTP/1.1 clients should observe a 2 connection
>>> limit to each server.
>>> Bob Briscoe, <bob.briscoe at bt.com> Networks Research Centre, BT
>>> B54/77 Adastral Park,Martlesham Heath,Ipswich,IP5 3RE,UK. +44 1473
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