Possible scenario... Subscriber bandwidth caps are in theory too high, if the ISP can't support it -- but if the ISP were to lower them, the competition's service would look better, advertising the larger supposed data rate -- plus the cap reduction would hurt polite users. In the absence of the P2P applications, the limits were fine, so hurting the P2P application may be a preferable solution to the ISP charging everyone more to support the excessive bandwidth usage of the 2-3% of subscribers who use P2P applications, or dropping that 6m bandwidth cap to a 256 kilobit cap just to be able to guarantee everyone can use it all at the same time. Many ISP customers might thank them for blocking P2P, if it keeps their subscription costs low --- in the absence of sufficient customer demand for P2P, it will be throttled, or filtered; if they're paying for a 1.5m connection (not a 6m) and it costs half the price of a normal 1.5m connection, but blocks P2P, many customers might like to make that tradeoff.
That's the ONLY thing they have to give us. Forget looking at L4 or alike, that will be encrypted as soon as ISPs start to discriminate on it. Users have enough computing power available to encrypt everything.
I'm afraid the response could then be for providers that limit P2P to begin treating everything encrypted as suspicious. The source and destination address are enough to do a lot in theory.... If the first packet exchanged between two hosts was sourced from a subscriber, then ISP monitoring mechanism can record a session... "Session started from inside to outside"; just like a stateful firewall. The ratio of bytes a customer sends to an address versus number of bytes they receive from that address can be used: anything above 1.0 is an upload, anything below 1.0 is a download; high ratio = reduced bandwidth cap. Very poor treatment could be given to sessions started from outside to inside. An address that only one or two subscribers exchange traffic with is probably a P2P app. An address that many subscribers try to exchange traffic with is probably an E-commerce site. Thus the whitelists could be built through automated means, just by counting the number of distinct inside sources per outside destination. ( if 1000 different customer source addresses send encrypted port 443 to one host, then that host could be automatically listed as "probably not a P2P host") -- a second possibility is the ISP could examine SSL certificate of remote destination -- f a site has gone through the trouble of having a high-grade X509 certificate signed by a for-fee official CA, then it's probably not a P2P peer. If a user tries to connect to a site that has no certificate signed by a recognized CA, then it's probably either a possible phisher a P2P peer --- these could in theory be blocked as a "stop phishing" measure. "Security" measure
Only if P2P shared network resources with other applications well does increasing network resources make more sense. If your network cannot handle the traffic, don't offer the services.
Exactly what they would seem to be doing. By blocking P2P uploads or throttling them, they are choosing to not offer full P2P access. Some ISPs may block P2P and be very quiet about it, and it's unfortunate, as customers would want to know about extra restrictions on the use of their X-megs connection. Generally warnings that excessive-bandwidth applications may be limited will be mentioned in ISPs' existing Acceptable Usage policies, they're probably just not outright saying "we block Xyz". P2P applications seem to be a valuable tool; however, it would be an ISP's available choice to refuse to offer it -- or require P2P users to pay extra, in proportion to the additional usage of their networks that are required to function with the service. When P2P usage is a burden on their network. Their network, their rules. The bigger issue I would say, is that in many areas, provider monopolies exist on affordable residential access services. So if "Provider A" happens to be the cable company in a local area, that owns all that infrastructure, and the rights to hang cable -- there's no opportunity for a "Provider B" to satisfy the demand, if they can't get a wire between them and their would-be customer.... No competition and no cost-effective alternative access path gives "Provider A" too much free reign. Free reign in terms of limiting consumer choice and forcing customers to accept substandard or partial services, when customers are tricked by shiny advertising into thinking they are buying high-grade fully featured services. -- -J