[ih] Installed base momentum (was Re: Design choices in SMTP)

[Jack Haverty]

On 2/9/23 14:57, Dave Crocker via Internet-history wrote:
> Such is the lesson of installed base momentum.
I agree - the installed base is a formidable obstacle to getting any 
kind of replacement propagated.   Stagnation and fragmentation into 
silos seems to be the result, as players introduce a desired new 
technology into just the components that they can control.

But I also wonder -- How did TCP overcome the momentum of the installed 
base?

At the time, in the 1990ish timeframe, there was a huge installed base 
of network technology.   Hundreds of thousands of computers utilizing 
networks based on SNA, SPX, XNS, Decnet, etc. etc.   TCP existed, but 
was a small player, confined largely to the academic and research 
communities.

But almost overnight, actually over just a few years, TCP became a real 
player, and then the dominant player, and by now all of the other 
technologies of that installed base have simply disappeared. The 
installed base of 1990 is gone without a trace.  Are there any computers 
anywhere still running those well-established technologies?   I haven't 
encountered any, but I wouldn't be surprised if some still existed.   
Perhaps something running Cobol somewhere.

So how did TCP manage to blast through that momentum of the installed 
base, creating such a chaos in the collision?   And how did it do it so 
rapidly?

Curiously, that collision of TCP with the installed base involved TCP/IP 
V4.   TCP/IP V6 has come along and its been quite a few years in 
transition.   It seems that the momentum of the installed base of TCP/IP 
V4 has blunted the adoption of TCP/IP V6.   Why?  What's different?

A similar situation seems to exist in other network areas, e.g., the 
mechanisms of electronic mail that we've been discussing.  New 
technologies can get invented and documented, but often never get widely 
deployed.  Why?   What magic incantations were used to deploy TCP in the 
1990s that have been apparently now lost.

Perhaps some historian has some answers....

Jack