[ih] Internet-history Digest, Vol 57, Issue 4

[John Shoch]

John Levine wrote:

"It's quite impressive that forty years later Ethernet has the same
logical formats as the Ethernet that ran on thick yellow coax, even
though at the hardware level practically nothing is the same."

In retrospect, the most important and enduring aspect of the DIX Ethernet
spec (now evolved through multiple generations of design over multiple
decades) was the packet format.

At Xerox we learned a lot from the1st generation implementation and
operation of the Experimental Ethernet (2.94 Mbps) and the Pup internet
architecture -- a combination which had well-matched but small address
fields.

James Carville advised Bill Clinton that, "It's the economy, stupid!"
I often observe, "it's the addressing, dummy!"

While the first generation worked well, with thousands of machines and
dozens of networks, it became clear it would not continue to scale.  It
required a much broader view of addressing, which led to the audacious idea
of 48-bit absolute addresses --- that's what allowed the 2nd generation DIX
Etherent and XNS internet to scale together.

The person we should thank for that is Yogen Dalal:
http://www.bitsavers.org/pdf/xerox/parc/techReports/OPD-T8101_48-Bit_Absolute_Internet_and_Ethernet_Host_Numbers.pdf
https://dl.acm.org/doi/10.1145/800081.802680

John Shoch

PS:  If you read the paper, you will see that the 48-bit absolute addresses
were intended for and implemented on both  the DIX Ethernet and as part of
XNS internet architecture -- a well crafted "impedance match."  (Other
people will have a much more informed view on the later, continuing
migration from IPv4 to IPv6.....)

>
> Message: 4
> Date: 21 Aug 2024 18:06:47 -0400
> From: "John Levine" <johnl at iecc.com>
> To: internet-history at elists.isoc.org
> Subject: Re: [ih] "This is the History of Ethernet."
> Message-ID: <20240821220647.6AD3392357F0 at ary.lan>
> Content-Type: text/plain; charset=utf-8
>
> It appears that Brian E Carpenter via Internet-history <
> brian.e.carpenter at gmail.com> said:
> >BTW, it's worth noting that the *current* IETF STD 37 for ARP (a.k.a. RFC
> 826) says:
> >
> >"This protocol was originally designed for the DEC/Intel/Xerox
> >10Mbit Ethernet.  It has been generalized to allow it to be used
> >for other types of networks.  Much of the discussion will be
> >directed toward the 10Mbit Ethernet."
>
> It's quite impressive that forty years later Ethernet has the same
> logical formats as the Ethernet that ran on thick yellow coax, even
> though at the hardware level practically nothing is the same.
>
> The Ethernets in my house are all gigabit twisted pair, and if I upgrade
> it'll likely be to 10G fiber.  But ARP still works.
>
> R's,
> John
>
>