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To: cs551@merlot.usc.edu
Subject: Re: CS551 Final1
Date: Thu, 30 Oct 2008 18:25:03 -0700
From: Bill Cheng <william@bourbon.usc.edu>

Someone wrote:

  > From the spec: "The check message is used by a node to see if it is still
  > connected to the core of the SERVANT network."
  > The Beacon node is a part of the core of the SERVANT network. If a beacon
  > node goes down, the rest of the beacon nodes would keep retrying to connect
  > to this node. Then why should a beacon node send check message?

You are absolutely correct.  Sorry, I miss-read the question!
(I guess I've been anwering too many e-mails!)  Although my
answer was correct (except for the "yes" part).  I thought
the question was about NOTIFY.
--
Bill Cheng // bill.cheng@usc.edu <URL:http://merlot.usc.edu/william/usc/>







  On Thu, Oct 30, 2008 at 2:22 PM, Bill Cheng <william@bourbon.usc.edu> wrote:
  
  > Someone wrote:
  >
  >  > Does a beacon node need to send check message when it loses
  >  > connection from one of its neighbors?
  >
  > Yes.  Remember, the rule is that if you have sent HELLO,
  > you need to send GOOD-BYE (i.e., NOTIFY).
  >
  >  > If a beacon node's NoCheck=1 and a non-beacon node's NoCheck = 0,
  >  > the beacon node will ignore the check message, so it means that
  >  > the non-beacon node will think itself is not part of the network,
  >  > is it right?
  >
  > This will never happen during grading.  Either NoCheck=0 for
  > all nodes, or NoCheck=1 for all nodes.  This is done so that
  > your part (2) does not depend on part (1) *completely* working
  > properly.
  >
  >  > For Error Code of notify message, which value does timeout (Auto
  >  > shutdown) use?
  >
  > Please see:
  >
  >    http://merlot.usc.edu/cs551-f08/msgs/bill/341.txt
  > --
  > Bill Cheng // bill.cheng@usc.edu <URL:http://merlot.usc.edu/william/usc/>