James A. Donald wrote:
This is obviously the right way to do it - the current
system has security and checking boundaries in the wrong
place, as well as being unnecessarily verbose.

Yet the plan never went anywhere.  What happened?

There is a gap between communications that are highly
efficient with TCP, and communications that are highly
efficient with UDP.  Brief transactions (which must be
reliable and two way, but are brief, are not efficient
with either one.

Indeed, ideally we would have one protocol that rapidly
starts to approximate TCP behavior with communications
that for which TCP is good (transferring large files)
and that approximates UDP with communications for which
UDP is good.

ref:
http://www.garlic.com/~lynn/aadsm25.htm#17 Hamiltonian path as protection against DOS

so much of postings at
http://www.garlic.com/~lynn/subnetwork.html#xtphsp

talks about attempting to standardize xtp as HSP (high-speed protocol) in ansi x3s3.3 (and iso chartered organization) ... which was under mandate that no standardization work could be done on networking protocol that was in violation of the OSI model. turns out xtp/hsp violated OSI model in at least three different ways.

xtp implementation was an adjunct to the tcp/ip (typically kernel) protocol stack.

I've often commented that both SSL and VPN were successful because they added security layer w/o requiring changes to the (kernel) tcp/ip protocol stack.

A person that we had worked with quite a bit introduced something (that since become to be called VPN) in gateway working group at the '94 san jose IETF meeting. my view was that it caused quite a bit of consternation in the ipsec crowd ... which were working on implementation that had hits to the underlying tcp/ip stack. VPN got a lot a lot of immediate uptake because it added security w/o requiring hits to the protocol stack in the end-nodes. The ipsec crowd somewhat reconciled VPN by starting to call it lightweight ipsec ... and some number of others then started called (regular) ipsec, heavyweight ipsec.

original (lightweight ipsec) vpn resulted in some peculiarities .... being a countermeasure to internet anarchy by being a boundary router between corporate intranets tunneled thru the internet ... w/o requiring changes to the end-points. part of the issue was that some of the router vendors had sufficient extra processing capacity to do the necessary vpn crypto and some didn't. so two months after the san jose ietf meeting ... you saw some router vendors announcing VPN "products" that were actually just add-on of traditional hardware link encryptor boxes.

so i've frequently claimed that ssl got market traction in much the same way that vpn got market traction ... by providing a solution that avoided hits to the (kernel) tcp/ip protocol stacks (modulo some really emergency server fixes at some high-end websites to handle the finwait list handling problem).

requiring coordinated (most frequently kernel) tcp/ip protocol stack upgrades for all (or majority of the) machines in the world, is a uptake inhibitor. ssl wasn't necessarily the optimal networking solution ... but it did have the minimum impact on existing deployed infrastructure.

in any case, some of the xtp features are starting to appear in some of the real-time streaming extensions ... like one of my favorites ... rate-based pacing (which i was forced to implement in high-speed backbones in the mid-80s)

many of the online xtp resources have since gone 404 ... however there still are a few around
http://usuario.cicese.mx/~aarmenta/frames/redes/xtp/biblio.html
http://www.pcmag.com/encyclopedia_term/0,2542,t=XTP&i=55105,00.asp
http://www.ccii.co.za/products/xtp.html

HTTP1.1 attempted to amortize multiple HTTP interactions across a single tcp session (attempting to mitigate the overhead of reliable session protocol for something that was frequently very transaction oriented). again w/o requiring hits to the underlying protocol stack.


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