Path: utzoo!attcan!utgpu!jarvis.csri.toronto.edu!mailrus!cs.utexas.edu!uunet!zephyr.ens.tek.com!tektronix!psueea!parsely!bucket!leonard
From: leonard@bucket.UUCP (Leonard Erickson)
Newsgroups: news.groups
Subject: Re: Well, use it...
Keywords: get the facts, jack
Message-ID: <1796@bucket.UUCP>
Date: 6 Dec 89 00:37:19 GMT
References: <7551@fear+loathing.UUCP> <128533@sun.Eng.Sun.COM> <17386@umn-cs.CS.UMN.EDU> <128633@sun.Eng.Sun.COM>
Organization: Rick's Home-Grown UNIX; Portland, OR.
Lines: 43

briang@bari.Sun.COM (Brian Gordon) writes:

<My understanding of usenet topology and yours must differ widely if you think
<that the problem is some single point.  Moreover, my understand of usenet
<"policy" and yours must differ widely if you think I can "apply pressure" to
<a feed.

<Usenet, as I understand it, can be viewed as a ring (ignoring the leaf nodes
<and the relatively uncommon site with multiple feeds).  Messages posted from a
<site are sent in both directions around the ring (again ignoring leaf nodes)
<and the message-id is used to keep it from "passing itself" in either
<direction.

<Suppose there are only 1,000 machines on this ring, and there are 200 between
<me and you in one direction and 800 in the other.  Suppose there are only
<10% of the sites that either do not carry sci.aquaria, or alias it to
<something else (so that articles that arrive in that newsgroup leave in
<another).  Assuming uniform distribution of those 100 sites, there are 20
<places in one direction and 80 in the other where your article is blocked from
<reaching your site, and the same number where your articles are blocked from
<reaching mine.  Even if it is 5% instead of 10%, the group, in effect, just
<doesn't exist as a net-wide information exchange medium.

The above bears no resemblance to the structure of the net. Check map entries.
Multiple feeds are *common*. The topology of Usenet is nowhere near as simple
as a ring or a tree. It's more of a multiply connected nightmare.

Many "leaf" sites have multiple feeds so as to cut down on the load to their
feed. Or to pick up groups that their feed doesn't get. I've seen articles
trickle in through the "leaf" sites here at bucket when our main feed was
down.

On the other hand, we missed a *lot* of articles, because newsadmins try to
keep the feeds set up as something resembling a tree. It *is* possible for
a single site to cut off most of the traffic in a group for *some* sites.
For other sites it's almost impossible.


-- 
Leonard Erickson		...!tektronix!reed!percival!bucket!leonard
CIS: [70465,203]
"I'm all in favor of keeping dangerous weapons out of the hands of fools.
Let's start with typewriters." -- Solomon Short