I'm not sure I totally agree. On Tue, Jun 24, 2008 at 2:07 PM, Jim Davis <[EMAIL PROTECTED]> wrote: > USENet is actually pretty bandwidth inefficient beast. "Your" server is > peered > with any number of other servers. Periodically your server asks all its peers > "got anything new?" - if so they send everything.
The number of peers for a news farm is pretty small. The number of peers for a P2P network is comparatively very large. My understanding is that most news goes through a small number of central hubs now-a-days and it's very unlikely that TWC (for example) is peering with 50 other nodes, but probably only 2-3 news major provider hubs. These are also likely the same hub companies their users are going to start using once they no longer have a local news source, effectively converting traffic that was local to the ISP network into public internet traffic. > In specific however each peer may choose to accept "everything", only some > groups or only certain messages (just new ones, or ones younger than a > certain age for example). In the end however if you've got a network of a > million peers then you've got a million copies of the message. There are almost certainly not a million news peers on the internet. Nowhere close. > Since the servers have vastly different speed and storage profiles you get > huge > diffences in "retention" - a huge server might be able to store a year's > worth of > data while an average server only a month and a tiny server only a day or two. True. > Compared to peer-to-peer which leaves the actual data on the "home" servers > until requested and, until then, just sends metadata USENet isn't as resource > friendly. Even a large binary message is shared amongst ALL peers even if > NOBODY ever requests it - if it's posted, it's transfered (again and again > and again). True, and these news propogation connections are (in theory) between two ISPs on a very high bandwidth connenction. Home based data transfers also go over this high speed connection, but at a the speed of the slowest user's home connection, usually the upspeed max of that user divided by the number of upload fragments, which is very, very, very slow in comparison. > USENet was also not designed for binary transfers (although they make up > the vast bulk of the bandwidth used) and need to convert any binary files to > text - this often expands the files making them bigger in transmission than > in the native format. True. > Because of the uncertainty of USEnet (retention rate, peerage, etc) most > groups > have adopted procedures for ensuring quality transfers. One of these is > provide > PAR (parity) files for large binaries. Using these files any corrupted or > missing > message parts can be rebuilt (as far as I'm concerned it's witchcraft pure and > simple). The trouble is a full "PAR set" needs to be, usually, about 20% of > the > file size. It's also generally accepted practice to include a sample of any > media files. True. > So a 700 Meg movie downloaded from peer-to-peer would be 700 meg. A 700 Meg > movie on USENet is 750 meg converted to text, plus, say 160 meg of PAR files > plus maybe a 30 meg sample file. And, again - these are all copied to every > peer > regardless of demand. A 700 Meg movie on a peer-to-peer network that nobody > ever requests uses essentially zero bandwidth. Okay, let's accept those numbers and do some math. Given 1000 clients downloading the same 700 meg file two ways. Either P2P clients or via News. Let's say there are 100 news servers, each feeding 10 people. 1) First, P2P - 1000 clients on a 700mb file at a 1:1 UL/DL ratio - 700,000mb over the public internet - 700,000mb over local ISP network 2) Next Usenet - 100 news servers transferring 780 (file+encoding+pars) a max of 99 times - 77,200mb over the public internet - 780,000mb over local ISP lines 3) Last, consider my numbers are wrong and it's 10 news servers feeding 100 people each - 7,020mb on public internet - 780,000mb over local ISP lines Even the worst usenet case (2) leaves 622,800 spare mb of internet bandwidth for those messages that get downloaded and never read off a server. That's 89%. If 89% of the messages on a news server were never read, P2P would only just break even with usenet. Yes, the local bandwidth is higher, but the trade off is worth it methinks. > USENet is also limited geographically: you connect to whatever server you > connect to. A closer server (even a peer) might be faster, but you don't have > access. Only if you are using a public server and not a local ISP server. > Peer-to-peer attempts to optimize the connection by downloading files from > the closest/fastest peer that hosts them and downloading using multiple hosts. > Once you have the file you also become a new node, a new host, for that file > thus allowing the system to optimize even further. Once I download something > from USENet it's mine and nobody else can see it. True, but all that P2P traffic is still public internet traffic. Usenet traffic is primarily local ISP traffic. > In short USENet servers act a lot like a peer-to-peer network where everybody > is constantly requesting every file from everybody else. For the end user > USENet is more like the Web - a provider and a consumer with a very large > downstream and very small upstream data flows. I'd say more like Akami than the general web. Again, news servers don't peer with "everyone", just certain peers they have agreements with. At the ISP I worked at just after college, we actually only peered with one provider. > This is simplistic of course - there are all sorts of tricks. On-the-wire > compression helps text-only USEnet more than peer-to-peer and much > of USENet traffic is still run over the relatively open backbone connections - > it's the last mile connections that are truly getting clogged and these are > exactly what's leveraged most by peer-to-peer. Yup. Plus, usenet doesn't saturate your upstream like P2P > But in the end I'm still a little suprised that USENet doesn't have a > stronger showing. Heh - longer reply than I meant, but I am still not surprised. ;) -Cameron ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~| Adobe® ColdFusion® 8 software 8 is the most important and dramatic release to date Get the Free Trial http://ad.doubleclick.net/clk;203748912;27390454;j Archive: http://www.houseoffusion.com/groups/CF-Community/message.cfm/messageid:262630 Subscription: http://www.houseoffusion.com/groups/CF-Community/subscribe.cfm Unsubscribe: http://www.houseoffusion.com/cf_lists/unsubscribe.cfm?user=89.70.5
