Talk:ALOHAnet

Two reasons?

The following discussion is closed. Please do not modify it. Subsequent comments should be made on the appropriate discussion page. No further edits should be made to this discussion.

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First section said it was important for two reasons, but only listed one. Was the other removed? Removed "two reasons". Tualha 16:30, 30 Nov 2003 (UTC)

I know the answers to lots of the questions here, after doing a lot of digging. I am writing a paper/talk about this, and will write up a summary for this place, but please be a bit patient. [Ignatios Souvatzis]

The discussion above is closed. Please do not modify it. Subsequent comments should be made on the appropriate discussion page. No further edits should be made to this discussion.

Menehune

I figure the menehune needs a mention (and some explanation). The page at http://research.microsoft.com/~gbell/Computer_Structures_Principles_and_Examples/csp0432.htm explains it a bit (with a uselessly small diagram). And I think we should say something like "...this network concentrator was named the MENEHUNE, after a mischievous type of polynesian fairy (see Menehune)". I'd add it in myself, but I can't really figure out where it belongs in the article. -- Finlay McWalter | Talk 21:37, 16 Feb 2004 (UTC)

Discussed in [[ALOHAnet#Hardware}} and ALOHAnet#Network_architecture ~Kvng (talk) 17:40, 25 June 2024 (UTC)

The ALOHAnet did not have CS!

It seems clear to me that the article is incorrect in stating that the ALOHAnet network was using CSMA.

With one frequency being used for "multiple access" and the other for the acknowledgements "broadcast" it is clear that this cannot be the case.

Stations would not be able to "listen" (detect carrier) since they just transmitted on MA channel and listened only to the "broadcast" channel for the acknowledgements of their messages.

The system would therefore be best described as MA/CD, but even the "CD" is with a twist. The stations did not really detect collisions, however, they "knew" there had been a collission (or some other problem) when they did not get their acknowledgement on the broadcast channel.

CS was only "invented" by Metcalfe around 1976 and he also made CD a feature of every station ...

Agreed

I'm going to rewrite this later... Notanotheridiot 18:26, 24 April 2007 (UTC)

ALOHAnet#Other_protocols indicates that ALOHAnet led to development of CSMA but there is no longer an assertion the CSMA was used in ALOHAnet. ~Kvng (talk) 17:43, 25 June 2024 (UTC)

The ALOHA protocol

I removed: (like a grade school classroom at recess) from the end of: This means that 81.6% of the total available bandwidth is basically being wasted due to stations trying to talk at the same time.

possible mistake

I have never cotributed to wikipedia before, so I won't change the article itself, since I don't really know how. But, as I am currently doing a project concerning ALOHANET, while searching for the actual bitrate of ALOHANET I found this document: http://ethernethistory.typepad.com/papers/ALOHAnet.pdf On page 12 it says that ALOHANET was run on two [u]24000 baud[/u] channels, not 9600 as it is written in this article. Someone visiting this place - please verify my information.

Dariusz Wawer [scyth*at*tenbit.pl], 02.12.2007 18:26 —Preceding unsigned comment added by 82.210.137.42 (talk) 17:28, 2 December 2007 (UTC)

24,000 is mentioned on the page labeled 7, the 12th page in the above-linked PDF. This paper was published in 1970 before the network was operational so is probably not a great source for the capabilities of the built network. Another source from 1981 cited in this WP article indicates 9600. ~Kvng (talk) 17:53, 25 June 2024 (UTC)

Miscellaneous Mistakes

Reading the original ALOHANET paper [1] is helpful. Errors:

• The data rate on the radio channels was 24,000 baud, not 2400 or 9600 baud. That's consistent with the allocation of 100 kilohertz of spectrum for each channel. By modern standards, that's terrible bandwidth utilization, but modems were very primitive then.
• The remote terminals were not "teletypes". The article uses that word, but the paper does not. The paper describes a typical load as "each user sending one message every 30 seconds". So this was a store-and-transmit terminal, like some predecessor of an IBM 3270. That makes sense: the central machine was an IBM 360/65. which was designed to work with such terminals, not with teletypewriters. It also meant that response delays on the order of seconds weren't a problem.
• Note that there's no contention on the outbound traffic from the Menuhene, and that most of the traffic is outbound (computer to user).

Incidentally, when I first saw an Ethernet on a tour of the Xerox PARC in 1975, and it was described to me by Alan Kay as "an ALOHAnet with a captive ether". --John Nagle (talk) 06:33, 24 October 2008 (UTC)

See above for speed discussion.

ALOHAnet#Hardware mentions teletype as a possible interface but that connects to the TCU which presumably does the store-and-transmit you describe ~Kvng (talk) 17:57, 25 June 2024 (UTC)

1) There are N nodes attempt to send data at time T. 2) The probability of successful transmission of one node is p s

The equation put like this out of context is difficult to understand. Where does this comes from? What are the symbols (i for example is not defined anywhere)? If someone can provide me the reference from where this comes from, I can fix it. — Preceding unsigned comment added by Ingframin (talk • contribs) 15:02, 24 July 2019 (UTC)

i no longer appears in the equations. They look adequately documented and self-consistent at this point. Their derivation is not explained.

The section has a reference to Tannenbaum but no page number is given so not immediately clear where the content in ALOHAnet#Protocol comes from. There is a discussion of probabilities starting on page 10 in [2] and similar equations. Perhaps this would be a better source. ~Kvng (talk) 18:09, 25 June 2024 (UTC)