Re: ARPAnet "Congestion"


Mark Horton (mark@cbosgd.att.com)
Tue, 30 Sep 86 17:05:41 edt


>My host spends
>90% of it's time on the ARPAnet sending and receiving INFO-THIS, and INFO-THAT.
>Also, I have multiple users receiving the same message from INFO-WHATEVER
>as separate TCP connections to my host.

If the ARPANET mailing lists do turn out to be the cause of the problem,
I'd like to suggest a possible solution: Netnews.

Netnews was invented on the UUCP network, where we didn't have the
seemingly "unlimited" bandwidth of the ARPANET. It had to survive
on 1200 baud dialup lines with UUCP. Nonetheless, we still manage
to push around about a megabyte/day of traffic over dialups. (This
figure 1MB/day counts each message only once, not once per recipient.)

It's been possible for UNIX sites on the ARPANET to exchange netnews
via UUCP or SMTP Mail for years now. Even these primitive methods
have many benefits (in our perception) over mailing lists:

(1) Only one copy of each message is sent to each system (although
we do sometimes have redundant links, sending redundant copies, for
extra reliability, duplicates are weeded out using Message-ID so
the users rarely see a duplicate.)

(2) Error messages don't go to the sender, they automatically go to the
person responsible for the link in question.

(3) Users see their "news" separately from their "mail" (unless they
want their news mailed to them, which is also possible but inefficient)
which means that mail will have higher priority than news for most users.
(By "news" I mean what's considered "mass mailing" on the ARPANET.)

(4) Users get other benefits, such as grouping of subjects and discussions,
and never have to go through a moderator or list maintainer to start
reading or posting to a newsgroup.

(5) Only one copy is kept on each machine's disk, rather than one copy
in each user's mailbox.

(6) News is automatically expired after two weeks (or whatever it's
locally configured to) so the disk usage is fairly constant; still,
users can join into the middle of a discussion and immediately have
two weeks worth of "back issues".

(7) Cross-posting allows a discussion to go on in multiple forums
(e.g. header-people and namedroppers) while sending only one copy
of each message around, and each user sees each message only once.

(8) By batching news, there is less transport overhead. Each hour,
a host may accumulate all new news and send it to its neighbors.

(9) All news goes through the same pipe, so it's easy to gather
statistics about traffic volume, both total and per-group. We
have also recently found a way to measure readership.

Even better methods are evolving. NNTP allows transfer of netnews
efficiently over TCP, and allows one machine to serve as a remote
disk so you don't need a copy of netnews on every machine. Stargate
will allow you to get moderated news from any cable TV service that
carries WTBS, or any satellite dish that can get WTBS.

The major problems with using netnews on the ARPA Internet have
historically been

(1) The implementations run under UNIX, and nobody has written one
for TOPS 20. (But I've heard rumors of an NNTP compatible TOPS 20
implementation under development.)

(2) Many users prefer to keep their mail and news lumped together
in their mailbox. (I can't understand this, but I guess it's a
religious issue, like which editor you use.) We have several
user interfaces for netnews, optimized to reading large volumes
of traffic, and encouraging good manners among the posters.

Usenet is the network currently carrying netnews, and includes large
chunks of UUCP as well as many ARPA Internet Usenet hosts. (If the
host runs UNIX and is a major Internet host, chances are good it's
on Usenet, although representation is light at some of the senior
ARPANET universities like MIT, CMU, and Stanford.) Some fraction of
the ARPA mailing lists are gatewayed into Usenet newsgroups, including
the TCP-IP list (I'm posting this as a Usenet message, and it will be
transparently be sent to the moderator.)

Usenet is a network, netnews is a technology. If mailing lists are
congesting the ARPANET, it may be possible to use the netnews technology
to carry the same amount of traffic at far less cost to the network,
simultaneously making the mailing lists more widely available and
cutting down on the workload of mailing list maintainers. (Most unmoderated
Usenet newsgroups don't have anyone "in charge" of them, they run themselves.)

Let's see where the load is really coming from; if mailing lists turn
out to be the culprit, I offer netnews as an alternative to cutting back.

        Mark



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