My apologies if I wasn't clear -- my point was that caching toward the client base changes installed architectures, an expensive proposition. If caching will find any success it needs to be at the lowest possible price point, which means collocating where access and transport meet, not in the field. I have little reason to believe that providers are going to cache for the internet to solve their last-mile upstream challenges. Frank -----Original Message----- From: Rich Groves [mailto:rich@richgroves.com] Sent: Monday, October 22, 2007 11:49 PM To: frnkblk@iname.com; nanog@merit.edu Subject: Re: Can P2P applications learn to play fair on networks? Frank, The problem caching solves in this situation is much less complex than what you are speaking of. Caching toward your client base brings down your transit costs (if you have any)........or lowers congestion in congested areas if the solution is installed in the proper place. Caching toward the rest of the world gives you a way to relieve stress on the upstream for sure. Now of course it is a bit outside of the box to think that providers would want to cache not only for their internal customers but also users of the open internet. But realistically that is what they are doing now with any of these peer to peer overlay networks, they just aren't managing the boxes that house the data. Getting it under control and off of problem areas of the network should be the first (and not just future) solution. There are both negative and positive methods of controlling this traffic. We've seen the negative of course, perhaps the positive is to give the user what they want ......just on the providers terms. my 2 cents Rich -------------------------------------------------- From: "Frank Bulk" <frnkblk@iname.com> Sent: Monday, October 22, 2007 7:42 PM To: "'Rich Groves'" <rich@richgroves.com>; <nanog@merit.edu> Subject: RE: Can P2P applications learn to play fair on networks?
I don't see how this Oversi caching solution will work with today's HFC deployments -- the demodulation happens in the CMTS, not in the field. And if we're talking about de-coupling the RF from the CMTS, which is what is happening with M-CMTSes (http://broadband.motorola.com/ips/modular_CMTS.html), you're really changing an MSO's architecture. Not that I'm dissing it, as that may be what's necessary to deal with the upstream bandwidth constraint, but that's a future vision, not a current reality.
Frank
-----Original Message----- From: owner-nanog@merit.edu [mailto:owner-nanog@merit.edu] On Behalf Of Rich Groves Sent: Monday, October 22, 2007 3:06 PM To: nanog@merit.edu Subject: Re: Can P2P applications learn to play fair on networks?
I'm a bit late to this conversation but I wanted to throw out a few bits of info not covered.
A company called Oversi makes a very interesting solution for caching Torrent and some Kad based overlay networks as well all done through some cool strategically placed taps and prefetching. This way you could "cache out" at whatever rates you want and mark traffic how you wish as well. This does move a statistically significant amount of traffic off of the upstream and on a gigabit ethernet (or something) attached cache server solving large bits of the HFC problem. I am a fan of this method as it does not require a large foot print of inline devices rather a smaller footprint of statics gathering sniffers and caches distributed in places that make sense.
Also the people at Bittorrent Inc have a cache discovery protocol so that their clients have the ability to find cache servers with their hashes on them .
I am told these methods are in fact covered by the DMCA but remember I am no lawyer.
Feel free to reply direct if you want contacts
Rich
-------------------------------------------------- From: "Sean Donelan" <sean@donelan.com> Sent: Sunday, October 21, 2007 12:24 AM To: <nanog@merit.edu> Subject: Can P2P applications learn to play fair on networks?
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.
While it may seem trivial from an academic perspective to do some things, for network engineers the tools are much more limited.
User/programmer/etc education doesn't seem to work well. Unless the network enforces a behavor, the rules are often ignored. End users generally can't change how their applications work today even if they wanted too.
Putting something in-line across a national/international backbone is extremely difficult. Besides network engineers don't like additional in-line devices, no matter how much the sales people claim its fail-safe.
Sampling is easier than monitoring a full network feed. Using netflow sampling or even a SPAN port sampling is good enough to detect major issues. For the same reason, asymetric sampling is easier than requiring symetric (or synchronized) sampling. But it also means there will be a limit on the information available to make good and bad decisions.
Out-of-band detection limits what controls network engineers can implement on the traffic. USENET has a long history of generating third-party cancel messages. IPS systems and even "passive" taps have long used third-party packets to respond to traffic. DNS servers been used to re-direct subscribers to walled gardens. If applications responded to ICMP Source Quench or other administrative network messages that may be better; but they don't.