PLEX86  x86- Virtual Machine (VM) Program
 Plex86  |  CVS  |  Mailing List  |  Download  |  Computer Folklore

Tokenring vs Ethernet 10 years later 3743


Gilbert Saint-Flour

there are a whole bunch of issues.

as part of the SAA terminal emulation strategy,

the T-R cards were built with per adapter thruput targeted at the terminal emulation market segment (say 300 PCs on the same ring). austin had designed & built their own 4mbit t-r (16bit isa) for workstation environments. for rs-6000 they were forced to use the corporate standard 16mbit microchannel t-r card. this card had lower per card thruput than the pc-rt 4mbit t-r card (they weren't allowed to do their own 16mbit microchannel t-r card that had even the same per card thruput as their 4mbit 16bit ISA t-r card).

as part of moving research up the hill from sjr to alm, the new alm building had extensive new wiring. however, in detailed tests they were finding that 10mbit ethernet had higher aggregate thruput and lower latency over the cat5 wiring than 16mbit t-r going over the same cat5 wiring.

in the SAA time-frame we had come up with 3-tier architecture

and were out pitching it to customer executives .... including examples showing 10mbit (cat5 wiring) ethernet deployments compared to 16mbit t-r deployments (using same cat5 wiring).

we were taking lots of heat from SAA forces which were actively trying to contain 2-tier-client-server and return the paradigm to the terminal emulation from the first half of the 80s (so you didn't need faster per card thruput because you were stuck in terminal emulation paradigm and you were stuck in terminal emulation paradigm because of the limited per card thruput).

we were also taking lots of heat from the t-r contingent. one of the t-r centers had published a paper showing 16mbit t-r compared to "ethernet" ... with ethernet degrading to less than 1mbit aggregate effective thruput. it appeared to be using the ancient 3mbit ethernet specification which didn't even include listen before transmit (part of the 10mbit standard).

Google Architecture 3744
Bill Richter and the difference between that and loosely-coupled or parallel sysplex? long ago and far away, my wife was con'ed to going to POK to...

about the same time, annual acm sigcomm had a paper that did some detailed look at commoningly deployed ethernet. one of the tests had 30 stations in tight low-level device driver loop transmitting minimum sized packets as fast as possible. In this scenario, effective aggregate thruput of 10mbit ethernet dropped off to 8.5mbits from a normal environment with effective aggregate thruput of 9.5mbits.

disclaimer: my wife is co-inventor for token pbutting patents (US and international) from the late 70s.


List | Previous | Next

Google Architecture 3744

Alt Folklore Computers Newsgroups

Tokenring vs Ethernet 10 years later 3742