Re: wanted: wireless magic tricks
Well, that is quite wonderful, but when I approached this problem with a collegue of mine over a sat link for a client that wasn't our experience and after considerable tweaking we ended up having to settle for less.
PS: got pointers to documents detailing the 500mbps over OC-12 sat link? email addr will do, as well, I'd love to find out what they did.
Yep, sorry -- I should have included a pointer. Try: David E. Brooks, Craig Buffinton, Dave R. Beering, Arun Welch, William D. Ivancic, Mike Zernic, Douglas J. Hoder. ACTS 118x Final Report High Speed TCP Interoperability Testing, July 1999. http://ctd.grc.nasa.gov/5610/publications/TM-1999-209272.pdf In the first couple of pages they show a results of 473 Mbps over an OC-12 circuit (a little less than line rate, but still quite good) using Solaris. Results with other operating systems varied. I seem to remember a presentation at the TCP Over Satellite IETF WG where over 500 Mbps was reported. My main point was that there is nothing wrong with the TCP *protocol* that makes it under-perform at large delay*bandwidth products. The implementations are not necessarily up to the job in some cases, but the protocol is sound. (Further reference might be the TCPSAT WG's two RFCs: 2488 and 2760). allman --- Mark Allman -- BBN/NASA GRC -- http://roland.grc.nasa.gov/~mallman/
On Thu, Aug 16, 2001 at 02:00:24PM -0400, Mark Allman wrote:
Well, that is quite wonderful, but when I approached this problem with a collegue of mine over a sat link for a client that wasn't our experience and after considerable tweaking we ended up having to settle for less.
PS: got pointers to documents detailing the 500mbps over OC-12 sat link? email addr will do, as well, I'd love to find out what they did.
Yep, sorry -- I should have included a pointer. Try:
David E. Brooks, Craig Buffinton, Dave R. Beering, Arun Welch, William D. Ivancic, Mike Zernic, Douglas J. Hoder. ACTS 118x Final Report High Speed TCP Interoperability Testing, July 1999. http://ctd.grc.nasa.gov/5610/publications/TM-1999-209272.pdf
Thanks. [..]
My main point was that there is nothing wrong with the TCP *protocol* that makes it under-perform at large delay*bandwidth products. The implementations are not necessarily up to the job in some cases, but the protocol is sound. [..]
FWIW, I wasn't bashing TCP, I was reporting experience data. -- Christian Kuhtz <ck@arch.bellsouth.net> -wk, <ck@gnu.org> -hm Sr. Architect, Engineering & Architecture, BellSouth.net, Atlanta, GA, U.S. "I speak for myself only."
Christian Kuhtz <ck@arch.bellsouth.net> writes:
My main point was that there is nothing wrong with the TCP *protocol* that makes it under-perform at large delay*bandwidth products. The implementations are not necessarily up to the job in some cases, but the protocol is sound.
FWIW, I wasn't bashing TCP, I was reporting experience data.
You can find details of tuning TCP for different operating systems courtesy of the Pittsburgh Supercomputing Center at: http://www.psc.edu/networking/perf_tune.html -tex -- ------------------ Jon Allen Boone tex@delamancha.org
Then there are performance-enhancing proxies that terminate the TCP session, turn the data into UDP to send over sat, and then re-originate as TCP. This eliminates the adverse effects of bandwidth-delay over sat links. See Mentat, FlashNetworks and Fourelle for PEPs. This is of course doable over satellite, the problem probably is the "occasional-use" nature of the BW requirement, its likely to bump up the cost per Mb considerably over operating a full time connection. jm
Well, that is quite wonderful, but when I approached this problem with a collegue of mine over a sat link for a client that wasn't our experience and after considerable tweaking we ended up having to settle for less.
PS: got pointers to documents detailing the 500mbps over OC-12 sat link? email addr will do, as well, I'd love to find out what they did.
Yep, sorry -- I should have included a pointer. Try:
David E. Brooks, Craig Buffinton, Dave R. Beering, Arun Welch, William D. Ivancic, Mike Zernic, Douglas J. Hoder. ACTS 118x Final Report High Speed TCP Interoperability Testing, July 1999. http://ctd.grc.nasa.gov/5610/publications/TM-1999-209272.pdf
In the first couple of pages they show a results of 473 Mbps over an OC-12 circuit (a little less than line rate, but still quite good) using Solaris. Results with other operating systems varied. I seem to remember a presentation at the TCP Over Satellite IETF WG where over 500 Mbps was reported.
My main point was that there is nothing wrong with the TCP *protocol* that makes it under-perform at large delay*bandwidth products. The implementations are not necessarily up to the job in some cases, but the protocol is sound.
(Further reference might be the TCPSAT WG's two RFCs: 2488 and 2760).
allman
--- Mark Allman -- BBN/NASA GRC -- http://roland.grc.nasa.gov/~mallman/
-- jon@interpacket.net Chief Science Officer ------------------------------------------------------------------ Verestar Networks, Inc. http://www.verestar.com 1901 Main St. tel (310) 382 3300 Santa Monica, California 90405 fax (310) 382 3310 ------------------------------------------------------------------
participants (4)
-
Christian Kuhtz -
Jon 'tex' Boone -
Jon Mansey -
Mark Allman