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

[John Day]

They were still station ‘addresses’. Yogen says in the article that they were device-ids. It was obvious when I first saw them that 48-bits assigned at the factory that the main reason was to make it easy to attach to the network.

Ethernet was never about data com but about distributed computing, and at those speeds they didn’t need to stingy with the bits in the header. (That was a general attitude at the time among that set of people, i.e., going way beyond what was normal or could be done easily knowing the hardware would catch up.

Totally different, but did you ever see how Englebart’s NLS *really* worked?  ;-)

> On Aug 22, 2024, at 19:56, Karl Auerbach via Internet-history <internet-history at elists.isoc.org> wrote:
> 
> I was at the ACM Sigcomm event in Mexico City when Y. Dalal mentioned 48-bit addresses.  I remember the murmur of surprise that swept over the audience.
> 
> 	--karl--
> 
> On 8/22/24 12:10 PM, John Shoch via Internet-history wrote:
>> 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
>>> 
>>> 
> 
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