wb8foz@mthvax.cs.miami.edu (David Lesher) (03/31/91)
This is such a naive question, and so clearly displays my lack of
knowledge, that I might as well ask........:-]
As I understand it, there are several methods that keep Site X from
getting a given article multiple times.
The first is the path line. News @ X looks at the path, and if it sees
itself, it spits it out. Second, for a given article, it compares the
message-ID to those in the active file.
Now on an leaf node UUCP site, the sending site sends everything, cuz
there is no way that stuff (except locally posted things) get there.
On a non-leaf UUCP fed site, I've seen "I have" and "Send Me" messages
in the control group and I guess that is how the receiver tells the
sender what to {not} pass.
How do sites with multiple NNTP feeds keep from getting thousands of
duplicates? I can see how they can TRASH them (when they get them) by
comparing the message-ID's to those in the active file, but how do they
avoid wasting the bw to get them in the first place? Do they engage in
their own version of "I Have/Send Me" somehow?
Where in Cnews are such items as what you send to whom, and what
you receive from whom, set?
{Please regard this message as one of those "There are 12 things
wrong in this picture" problems. Correct all parts of it.}
--
A host is a host from coast to coast.....wb8foz@mthvax.cs.miami.edu
& no one will talk to a host that's close............(305) 255-RTFM
Unless the host (that isn't close)......................pob 570-335
is busy, hung or dead....................................33257-0335henry@zoo.toronto.edu (Henry Spencer) (04/02/91)
In article <1991Mar30.212159.16368@mthvax.cs.miami.edu> wb8foz@mthvax.cs.miami.edu (David Lesher) writes: >How do sites with multiple NNTP feeds keep from getting thousands of >duplicates? NNTP is an interactive protocol; those other sites don't feed you duplicates because they ask you "do you have xxx already?" before they send it. >Where in Cnews are such items as what you send to whom, and what >you receive from whom, set? The sys file decides the vast majority of such issues. See news(5). -- "The stories one hears about putting up | Henry Spencer @ U of Toronto Zoology SunOS 4.1.1 are all true." -D. Harrison| henry@zoo.toronto.edu utzoo!henry