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To: cs551@merlot.usc.edu
Subject: Re: Landmark routing
Date: Sat, 18 Oct 2008 14:59:46 -0700
From: Bill Cheng <william@bourbon.usc.edu>

Someone wrote:

  > I had a question about slide 9 of lecture 8. During the lecture after node 8
  > was promoted to LM2 we verified the red rule.

Yes.  You need to verify the red rule for i=1, i.e., "every
LM1 router is seen by at least one LM2 router".

  > Was this necessary since we
  > already verified that Node 3 was an LM1 router than could see everyone (you
  > could route downward to everyone with this information).  Wouldn't we only
  > need to recheck the red rule if we had needed multiple level 1 routers
  > (which were potential "far" away from each other) to satisfy the red rule in
  > the previous iteration.

May be for the particular network it works out.  But in
general, we must check after every round.
--
Bill Cheng // bill.cheng@usc.edu <URL:http://merlot.usc.edu/william/usc/>