Due to the 'speed-of-light' thing, the culprit for the performance issue is TCP/IP. I had the privelage of speaking with an IBM genius in networking and he provided an easy explanation. TCP/IP uses 'sliding window' for flowcontrol. The window size can be up to 64k and varies depending on network conditions, configuration and other thngs. Assuming the full window during bulk downloads, you can send or receive 64k of data in one direction without waiting for an ack. Doing a bit of math reveals that 64k bytes end up being enough to keep a t1 busy even if there are long link delays. However, with very long delays, you cap out at about t1 speeds or whatever 64k times ack delay/time unit comes out to be no matter what the pipe advertises ( assuming large bandwidth). Things like http and ftp will feel it because they are TCP based. However, udp based communications are not locked into this since they do not manage a 'sliding window' or any other protocol level flow control, so in theory, you can transmit at wire speeds no matter what the delay, using udp. My understanding is that IPv6 anticipated this and is proposing a negotiated rate of transmission instead of a 'window' This would almost kill the effects of 'speed of light' concerns unless re-transmissions became an issue. With this in mind, the 'custom software' mentioned could easily be an IPv6 tunnel or similar. Since linux has IPv6 software in its collection, maybe using this would releive some of the perfoemance concerns experienced b y2 way sattelite communications....IMHO Jerry ----- Original Message ----- From: "Thomas Dodd" <ted@cypress.com> To: <psyche-list@redhat.com> Sent: Wednesday, October 23, 2002 4:17 PM Subject: Re: Direct TV Satellite connections > > > Neal D. Becker wrote: > > I believe you will find that this is a marketing decision. I am > > speaking strickly for myself on this, not as a representative of > > Hughes. > > My understanding is the software for DirectWay and StarBand > has some code to work around response times, and some caching > code to speed up browsing. > > The systems are useless for real 2 way work, so > don't put us a web server, or ftp file to another > machine. > > > But, this extra software makes browsing tolarable. > It's only written for M$ OSes, Win9x +, and I don't > know if it works well with NT either. > > A proprer way, would have been to write the code > for other OSes, but I think it was contracted out > to a a windoze shop. > > I've read that with StarBand you could remover the > ethernet->USB converter, and plug it in to a NIC. > It worked, but not well. DirectWay is probably > the same. Search for "StarBand" and "linux" to read more. > DirectWay will have the same issues. > > -Thomas > > > > -- > Psyche-list mailing list > Psyche-list@redhat.com > https://listman.redhat.com/mailman/listinfo/psyche-list -- Psyche-list mailing list Psyche-list@redhat.com https://listman.redhat.com/mailman/listinfo/psyche-list
