Sean Donelan wrote:
Much of the same content is available through NNTP, HTTP and P2P. The
content part gets a lot of attention and outrage, but network
engineers seem to be responding to something else.
If its not the content, why are network engineers at many university
networks, enterprise networks, public networks concerned about the
impact particular P2P protocols have on network operations? If it was
just a
single network, maybe they are evil. But when many different networks
all start responding, then maybe something else is the problem.
The traditional assumption is that all end hosts and applications
cooperate and fairly share network resources. NNTP is usually
considered a very well-behaved network protocol. Big bandwidth, but
sharing network resources. HTTP is a little less behaved, but still
roughly seems to share network resources equally with other users. P2P
applications seem
to be extremely disruptive to other users of shared networks, and causes
problems for other "polite" network applications.
What exactly is it that P2P applications do that is impolite? AFAIK they
are mostly TCP based, so it can't be that they don't have any congestion
avoidance, it's just that they utilise multiple TCP flows? Or it is the
view that the need for TCP congestion avoidance to kick in is bad in
itself (i.e. raw bandwidth consumption)?
It seems to me that the problem is more general than just P2P
applications, and there are two possible solutions:
1) Some kind of magical quality is given to the network to allow it to
do congestion avoidance on an IP basis, rather than on a TCP flow basis.
As previously discussed on nanog there are many problems with this
approach, not least the fact the core ends up tracking a lot of flow
information.
2) A QoS scavenger class is implemented so that users get a guaranteed
minimum, with everything above this marked to be dropped first in the
event of congestion. Of course, the QoS markings aren't carried
inter-provider, but I assume that most of the congestion this thread
talks about is occuring the first AS?
Sam
