Xref: utzoo tor.news:140 ont.uucp:386
Path: utzoo!yunexus!gen1!yunccn!shields
From: shields@yunccn (Paul Shields)
Newsgroups: tor.news,ont.uucp
Subject: Re: news
Summary: REPOST - The oscillations can be damped by restructuring connectivity
Keywords: news, flood, alarm
Message-ID: <304@yunccn>
Date: 16 Mar 88 05:51:28 GMT
Article-I.D.: yunccn.304
Posted: Wed Mar 16 00:51:28 1988
References: <8802050452.AA03771@gpu.utcs.toronto.edu> <314@yunexus.UUCP> <584@ncrcan.Toronto.NCR.COM> <440@spectrix.UUCP>
Reply-To: shields@yunccn.UUCP (Paul Shields)
Distribution: ont
Organization: York NCCN
Lines: 45

I'm re-posting this article because it didn't get out the last time
(about 3 weeks ago.)

In article <440@spectrix.UUCP> clewis@spectrix.UUCP (Chris R. Lewis) writes:
>...Spectrix has no real outgoing
>feeds, and we don't get a full feed either - still our spool area seems
>to "breathe" by 50% over a 3-7 day cycle.  A lot of this is due to
>our incoming throttle slowing down the incoming feed.

[...]
>Doesn't take much to see that without sufficient "damping" this could
>be self-perpetuating.  And, perhaps more importantly would induce very
>similar problems on both upstream and downstream neighbors.  Particularly
>if you're throttles were set very close to the end of the disk.

Here are a couple of ways to damp the oscillations: 

1) If we assume that the rate of news creation doesn't oscillate, but its 
delivery just comes in waves, we can make the waves cancel each other out
as follows: 

    (a) Have redundant connections to upstream neighbours (use the 
	ihave/sendme protocol.)

    (b) Divide the work amongst upstream neighbours. Ideally, the upstream
        sites will be chosen so that they are at different points in
        the curve of the wave from each other.  

	This reminds me, would it be a good idea to send the message size
	in the ".ihave" messages?  This would enable a site to pick up equal 
	amounts of news from two adjacent upstream neighbours. 

This may not be possible, as one upstream site may oscillate at a different 
frequency.  It would also not work if the entire network oscillates in one 
giant wave.

2) Make the flow as continuous as possible, by making the batches smaller,
and sending them more often.  Sites should send no more than x MB in any 
given session, and connect as frequently as possible to upstream and 
downstream sites.  This would increase the frequency of oscillations, but
decrease their amplitude.
-- 
Paul Shields, shields@yunccn.UUCP

Communication is a two-way street.  Don't get run over.