[comp.protocols.appletalk] Fastpath 'halting problem'

kenw@noah.arc.CDN (Ken Wallewein) (11/27/88)

  In a variety of different configurations and protocols, interactive sessions
over Appletalk often exibit rather severe jerkiness;  the session will simply
'sieze up' for periods up to several seconds.  In fact, I have observed the 
the entire Mac may freeze durint that time.

  All of these sessions have the following in common, so far:  they involve 
Macintoshes talking over Appletalk through a Kinetics Fastpath (2/3 _or_ 4) 
and Ethernet to a Vax.  The protocol could be Telnet, CTERM, or Pacer's PNP.

  The problem seems to be worse on older Fastpaths on busier networks...  but
I don't seem to be able to establish the exact cause of the problem.  I
_suspect_ the Fastpath, but I can't prove it.  I know we're not the only site 
experiencing the jerkiness, but so far Kinetics professes to be unaware of 
such a problem.

  Who else has seen this?  Is there some way we can establish the exact cause?

/kenw

bwk@mitre-bedford.ARPA (Barry W. Kort) (11/30/88)

In article <1474*kenw@noah.arc.cdn> kenw@noah.arc.CDN (Ken Wallewein) writes:

> In a variety of different configurations and protocols, interactive sessions
>over Appletalk often exibit rather severe jerkiness;  the session will simply
>'sieze up' for periods up to several seconds.  In fact, I have observed the 
>the entire Mac may freeze durint that time.
>
> Who else has seen this?  Is there some way we can establish the exact cause?

This happens from time to time on our network as well.  I suspect the
problem is due to lost packets on the Appletalk, caused by irregularities
in the Appletalk cabling.  Sometimes I just go around reseating
Appletalk connectors where they have worked loose here and there.

Try deliberately opening the Appletalk cable at the far end.  This
will create echoes and standing waves which disrupt the network.
Then see if the interactive session freezes until you restore
the cable termination.

--Barry Kort