[ih] Anticipating network and internetwork scaling

[Brian E Carpenter]

On 03-Feb-25 14:53, John Day via Internet-history wrote:
> Aren’t routing and forwarding tables state?

Yes, but they aren't *per packet* or *per flow* state.

(Not that the Internet is truly devoid of flow state.)

    Brian

> 
>> On Feb 2, 2025, at 20:48, John Shoch via Internet-history <internet-history at elists.isoc.org> wrote:
>>
>> In the last week there have been a number of interesting comments on
>> stateless gateways, which led to a broader question -- if one could have
>> predicted the eventual scaling of networks and the internet.
>>
>> On Jan. 26 jnc wrote:
>> "I don't think we could have been thinking 'this aspect of lack of state in
>> the internet packet switches [m]eans it will scale indefinitely' because I
>> don't think we had any idea, at that point, about how to do path selection
>> in
>> a global-scale internet - so global-scale internets could not have been in
>> our thinking."
>>
>> On Jan. 26 Vint Cerf responded, in part:
>> "I don't know that we recognized the scalability aspect
>>
>> but we definitely cared a lot about statelessness of the gateways"
>>
>> On Jan. 28 Len Kleinrock commented on the scalability of packet networks.
>>
>> On Jan. 28 Brian Carpenter noted:
>> "I just glanced through Baran's 1964 paper, and it clearly recognized
>> statelessness (and a standard packet header) as important for network
>> survivability and adaptive routing. But although he mentions networks
>> of intercontinental size, I didn't spot any discussion of scalability
>> as such.
>> Interestingly, exactly the same applies to Dave Clark's 1988 "Design
>> Philosophy" paper.
>> In RFC 1958 [published in 1996], we did note as principle 3.3 that "All
>> designs must scale readily to very many nodes per site and to many millions
>> of sites".
>> I guess that by then (1996) this was too obvious to ignore, and it was
>> written when IPv4 address exhaustion was considered inevitable.
>> Maybe somebody who knows the early literature better than me can find
>> something. But it's almost as if the intrinsic scalability of stateless
>> packet switching was an unnoticed and accidental property."
>>
>> I certainly don't know all "the early literature" but I would be remiss if
>> I did not point out that there were people who foresaw the problems of
>> internetwork scalability -- and actively worked on solutions.  In
>> particular, 15 years before that RFC (in 1981) Yogen Dalal wrote about the
>> migration from the first generation Xerox Ethernet and internet
>> architecture, to the second generation of each -- and how the desire to
>> scale led (at the suggestion of Will Crowther) to the need for a large,
>> flat address space and associated routing techniques:
>>
>> "We have described our reasons for choosing absolute host numbers in
>> internet addresses, and for using them as station
>> addresses on the Ethernet channel. The host number space should
>> be large enough to allow the Xerox internet architecture to have a
>> life span well into the twenty-first century. 48 bits allow for
>> 140,737,488 million physical hosts and mulitcast IDs each. We
>> chose this size based on marketing projections for computers and
>> computer-based products, and to permit easy management of the
>> host number space."
>> "We expect that the production of microcomputer chips will
>> increase in the decades that follow, and there will be
>> microprocessors in typewriters, cars, telephones, kitchen appliances,
>> games, etc."
>>      https://dl.acm.org/doi/pdf/10.1145/1013879.802680
>>
>> This was a really expansive vision about internet scaling and necessary
>> routing techniques, written about 45 years ago.  Yet Yogen and his team
>> didn't just think about a "global-scale internet" -- they were already
>> building one.
>>
>> John
>>
>> PS:  While the paper was published in 1981, the actual work had been going
>> on for some years.  It was unfortunate at the time that we could not share
>> the detailed work, but in general discussions with the internetworking
>> community we tried to leave a trail of early breadcrumbs, which an
>> interested reader might have been able to follow.  See for example, from
>> IEN 19 in 1978:
>> "The Implications of Hierarchical vs. Flat Address Spaces
>> It should be apparent that the structure of the address space is of central
>> importance: it is the major element of commonality in such an
>> [internetworking] environment, and can have a profound influence on the
>> naming mechanism "above" and the routing mechanism "below".
>> An address space can be partitioned in a hierarchical manner, or left as a
>> single uniform space. Use of a flat address space implies that:
>>     1. The address given to any resource must be unique over the whole
>>     domain; and,
>>     2. There is no structure to the address which might aid the routing
>>     process; instead, the routing mechanism must be able to handle all
>>     addresses, without segmenting them into parts (i.e., there is no
>>     area code [network number])."
>> -- 
>> Internet-history mailing list
>> Internet-history at elists.isoc.org
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>