Path: utzoo!attcan!uunet!husc6!think!ames!pasteur!ucbvax!noah.arc.CDN!kenw
From: kenw@noah.arc.CDN (Ken Wallewein)
Newsgroups: comp.protocols.appletalk
Subject: Speed of LocalTalk, gateways
Message-ID: <964*kenw@noah.arc.cdn>
Date: 13 Oct 88 16:58:00 GMT
Sender: usenet@ucbvax.BERKELEY.EDU
Organization: The Internet
Lines: 35


  I keep hearing about people saying LocalTalk is slow.  Frankly, I'm 
skeptical.  

  Think about it.  LocalTalk is rated at about 230 Kbps -- about the same as a
floppy disk drive, but without seek and skew latency delays.  It works out to
about 28 Kbytes per second.

  Even at 50% of optimum throughput, a person should be a able to launch an
application via LocalTalk in about a third of the time it seems to take from a
floppy disk. 

  I've been doing a little checking, comparing different kinds of sources.
Here are informal, approximate times to launch MacWrite.  Note: these are
_approximate_ times only! 

15	Floppy disk drive (800 K on Mac Plus)
20	Corvus Omnidrive (note: has 38 Kbaud bottleneck)
30	Pacer Via Kinetics Fastpath 3 to MicroVax II
~10	Mac Se <==(Localtalk)==> Mac II
		 <==(Northern Telecom's Meridian Lanstar @ 2Mb/sec)==> ?Server

  I haven't yet timed AlisaTalk, Tops, a Mac-based Appleshare server, or 
anything using Ethernet.

  However, the figures I have so far seem to indicate that _nobody_ saturates
LocalTalk, and that the bottleneck may well be in the gateway.  There are
rumours that Kinetics KFPS-4s are somewhat faster. 

  I'd be most interested in hearing other people's test results.

 /kenw
                                                                 A L B E R T A
Ken Wallewein                                                  R E S E A R C H
kenw@noah.arc.cdn                                                C O U N C I L