[Make-wifi-fast] Re: [Cake] Re: [ih] Bandwidth v Capacity [Early Internet Report when Vint was at Stanford (and DARPA PI)]

[dan <dandenson@gmail.com>]

FWIW, we're happy to educate customers and then make them terminology
snobs.  'brandwidth is a lie' has multiple meanings.  When someone asks
what the speeds are, I very often say 'near the speed of light'.  We lean
on 'Capacity' as interchangeable with 'Throughput'.  I dislike 'throughput'
for marketing because it's a rather clumsy combination of words for the
average person, ie 'put' is an odd word choice and 'through' doesn't really
describe receiving of data very well.  Also worth noting, I absolutely
despise the use of 'goodput', yuck I say.  I understand the why, but the
words don't flow and it sounds clumsy.

I'd like to see 'capacity' used by ISPs as a replacement for bandwidth, and
per Sebastian's previous comment on 'c', only ISPs via their marketing and
labelling can start to make this change.

On Sun, May 31, 2026 at 11:55 PM Sebastian Moeller via Cake <
cake@lists.bufferbloat.net> wrote:

> Mmmh, from the meta-peanut gallery
>
> a) The man's name was Heinrich Hertz, and so the unit's name is hertz as
> well, not herz. Typically I would just silently correcting this internally
> when reading a text and not bother, but when a text is trying to show how
> to correctly name things, it should lead by example.
>
> b) Just to be contrarian, how about using "data rate" or "information
> rate" when talking about what is achieved, capacity being the achievable
> limit of said rate and bandwidth being the spectrum allotted (I know, too
> easy)?
>
> c) That ship has sailed, language is adaptable and typically dies not ask
> permission when changing connotations and usage/meaning.
>
> d) Not that it matters, I agree that bandwidth and capacity should not be
> confused (but see c) ) or we end up with bangers like:
>         "out of a bandwidth of X Hz our modulation and encoding scheme
> allows a total bandwidth of Y Bits/second out of which a bandwidth of Z
> Bis/seconds were achieved in real world testing."
>
> Re
>
>
> > On May 31, 2026, at 13:49, Frantisek Borsik <frantisek.borsik@gmail.com>
> wrote:
> >
> > Forwarding for visibility - a great "rant" on the usage of "bandwidth" vs
> > "capacity", from Brian E. Carpenter
> https://profiles.auckland.ac.nz/bcar071
> >
> > To read more, from people like Vint Cerf or John Day, on this topic,
> take a
> > look into the archive:
> >
> https://elists.isoc.org/pipermail/internet-history/2026-May/thread.html#start
> >
> > All the best,
> >
> > Frank
> >
> > Frantisek (Frank) Borsik
> >
> >
> > *In loving memory of Dave Täht: *1965-2025
> >
> > https://libreqos.io/2025/04/01/in-loving-memory-of-dave/
> >
> >
> > https://www.linkedin.com/in/frantisekborsik
> >
> > Signal, Telegram, WhatsApp: +421919416714
> >
> > iMessage, mobile: +420775230885
> >
> > Skype: casioa5302ca
> >
> > frantisek.borsik@gmail.com
> >
> >
> > ---------- Forwarded message ---------
> > From: Brian E Carpenter via Internet-history <
> > internet-history@elists.isoc.org>
> > Date: Sat, May 30, 2026 at 11:55 PM
> > Subject: [ih] Bandwidth v Capacity [Early Internet Report when Vint was
> at
> > Stanford (and DARPA PI)]
> > To: Internet History <internet-history@elists.isoc.org>
> >
> >
> > Hi,
> >
> > Yes, that's a very nice slice of history. It leads me to one of my hobby
> > horses: when did the solecism of using "bandwidth" to mean "capacity"
> first
> > arise? This is something that should annoy every physicist, or anyone who
> > has read Shannon's foundational paper [1]. Unfortunately, it's become
> > firmly established in the Internet community and beyond. And it matters
> > because it quite often creates confusion, particularly in media reports.
> >
> > * Bandwidth is measured in herz (cycles per second) and is the frequency
> > range that a communication channel can transmit.
> >
> > * Capacity is measured in bits per second and is the amount of binary
> > information that a communication channel can transmit.
> >
> > There is no fixed relationship between the two (which is more or less the
> > main point of Shannon's paper). Anyone who ever heard the startup
> screeches
> > of a modem should know this.
> >
> > To illustrate the issue, page 1 of Vint's report says:
> >
> > "During the months of December (1975) and January (1976), we undertook
> > extensive and detailed timing measurements of the ELF VDH behavior to
> > ascertain the degree to which VDH performance affected total TCP
> > bandwidth and delay."
> >
> > That (and the other 14 occurrences of "bandwidth") should be "capacity."
> >
> > Page 8 says:
> >
> > "The actual
> > line utilization is about 20% in each direction, assuming a nominal 50
> > kbits/second available full-duplex capacity between ELF and the IMP."
> >
> > That's correct usage.
> >
> > My favourite sentence is on page 45:
> >
> > "Many of the experiments have been
> > frustrating, owing to a bug of some kind in UCL's buffer allocation
> scheme
> > causing them to crash irrevocably when attempting to achieve high
> > bandwidth."
> >
> > If only they had tried to achieve high capacity!
> >
> > So, my question is: when did this inaccurate use of "bandwidth" to mean
> > "capacity" first arise? It was clearly well established by 1975.
> >
> > I looked in Donald Davies's book [2], and it only uses "capacity" (I
> would
> > expect no less of him). Baran in 1964 [3] used "capacity" correctly many
> > times. He also used "bandwidth" correctly once [5] and debatably a second
> > time [6].
> >
> > Pierce [4] in 1961 was completely clear on the difference between
> bandwidth
> > and capacity (and he learned directly from Shannon).
> >
> > Regards/Ngā mihi
> >    Brian Carpenter
> >
> > [1] C. E. Shannon, "Communication in the Presence of Noise," Proceedings
> of
> > the IRE, vol. 37, no. 1, pp. 10-21, Jan. 1949
> > [2] D. W. Davies, D. L. A. Barber, W. L. Price & C. M. Solomonides,
> > "Computer Networks and their Protocols," Wiley, 1979
> > [3] P. Baran, "On Distributed Communications Networks," IEEE Transactions
> > on Communication Systems, Vol. 12 No. 1, 1964, pp. 1-9
> > [4] J. R. Pierce, "Symbols, Signals and Noise," Harper, 1961
> >
> > [5] "In a conventional circuit-switched system each of the
> > tandem links requires matched transmission bandwidths.
> > In order to make fullest use of a digital link, the post-
> > error-removal data rate would have to vary, as it is a
> > function of noise level."
> >
> > [6] "Most importantly, standardized data blocks permit
> > many simultaneous users, each with widely different band-
> > width requirements to economically share a broad-band
> > network made up of varied data rate links."
> >
> > On 30-May-26 15:13, Barbara Denny via Internet-history wrote:
> >> While poking around on DTIC,  I found this interesting early report on
> > the Internet while Vint was still at Stanford and Jon Postel was still at
> > SRI (How many of you knew that? :-))The period of performance is Nov
> > 15,1975 to Feb 15 1976.
> >> https://apps.dtic.mil/sti/tr/pdf/ADA024823.pdf
> >> You can find a little bit more info by using the contract number in
> dtic.
> >> Happy Reading,barbara
> > --
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> > https://elists.isoc.org/mailman/listinfo/internet-history
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