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From: sc268116@seas.gwu.edu (Kavosh Soltani)
Newsgroups: comp.sys.isis
Subject: ISIS Internals ???
Message-ID: <3128@sparko.gwu.edu>
Date: 26 Apr 91 16:14:28 GMT
Article-I.D.: sparko.3128
Reply-To: sc268116@seas.gwu.edu (Kavosh Soltani)
Distribution: na
Organization: The George Washington University, Washington D.C.
Lines: 24

After reading the ISIS manual and technical papers (TRs), I am still not 
completely clear on how ISIS exactly works.  Does any of the ISIS gurus out
there know the answer to the following:

   1) I know that monitors and watches are implemented as tasks by ISIS.
      But, where is the guarantee that they work?

      Example:
      If we have three user tasks, while the first is running, a value
      monitored is changed.  As described in the manual, the monitor is not
      triggered until all three tasks are completed.  But in the meantime
      the value may change again or something else may happen...

      Am I missing something?

   2) Original broadcast system of ISIS uses a sequencer and Coordinator-
      Cohort mechanism to implement its virtual synchronization and
      atomicity. But how is the original algorithm implemented to gurantee
      these features for the protocol itself?

      Does ISIS use timeouts, some form or token passing, or what to
      implement the protocol itself?

Thank you,