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From: LENOIL@XX.LCS.MIT.EDU.UUCP
Newsgroups: comp.protocols.appletalk
Subject: Re: appletalk error rates
Message-ID: <12346139500.18.LENOIL@XX.LCS.MIT.EDU>
Date: Wed, 28-Oct-87 13:49:49 EST
Article-I.D.: XX.12346139500.18.LENOIL
Posted: Wed Oct 28 13:49:49 1987
Date-Received: Sat, 31-Oct-87 09:23:41 EST
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Organization: The ARPA Internet
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    Date: 27 Oct 87 12:14 -0800
    From: Rick Sample <sample%ubc.csnet@RELAY.CS.NET>
    Subject: appletalk error rates
    
    Can someone tell me a reasonable rate for errors on the AppleTalk?
    Running Peek gives three types of errors: overruns, CRC errors,
    and time outs.  Are collisions included in these errors?  Is an
    error rate of 5% much more than normal?  Seems rather high to me.
    What might cause such a high rate?
    
    We have been having a lot of trouble with a flaky appletalk, and I
    am trying to debug it.  Any advice would be appreciated.

A reasonable CRC rate for AppleTalk Personal Network cabling would be .1% of
the total packets.  CRC errors in excess of that rate usually indicate an
unterminated network, or a network with a loop or spur.
 
 
Wrong:  --M--M--M
 
Wrong: M--M
       |  |
       M--M
 
Wrong: M--M--M--M
           |
           M
 
The least likely possibility (although it does occur) is a bad cable or
connection box.  The brute force way to isolate the fault is to use a
binary search: cut your network in half and see which half produces the CRC
error; divide that segment in half, etc.

Robert Lenoil
Apple Computer Inc.
Network Systems Development
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