[ih] Internet addressing history section

[Joe Touch]

> On Feb 16, 2019, at 5:51 PM, Grant Taylor <internet-history at gtaylor.tnetconsulting.net> wrote:
> 
> On 2/16/19 5:49 PM, Noel Chiappa wrote:
>> Although both links and processors are _much_ faster than they used to be, 
>> the speed of light (IOW point-point transmission delays) hasn't changed. 
> 
> I'll agree that the propagation delay hasn't changed.  But the amount of 
> time it takes to send X number of bytes is significantly less today than 
> it was 10, 20, 30, or 40 years ago.

Message transfer latency (the only one that matters, IMO), is a combination of:
	- generation latency
	- propagation latency
	- computational latency
	- aggregation latency
	- multiplexing latency

(I recently gave a tutorial on this at Sigcomm, and it was the focus of my thesis 25+ yrs ago)

These contribute to the overall latency of different communication technologies in various ways. I’m glad that you noticed that such latency is *of a message* (of size X), rather than an independent property (i.e., just asking “what’s the latency?” cannot be answered).

> 
> I have no idea if the time to send X number of bytes has changed enough 
> to fundamentally alter equations or not.
> 
> But I do remember discussions about ping times across 10 BaseT LAN vs 
> 100 BaseT or even 1000 BaseT.  People liked to say it's a small enough 
> amount of data that it shouldn't matter.  Yet it does.

It also takes longer than it looks like it should across modems and RF links, sometimes because of coding delays (aggregation latency above) and channel access latencies.

FWIW, propagation delay has gone up (from coax LANs @0.8c to twisted pair @0.6c) then down (newer twisted pair approaches 0.8c again) and fiber is 0.65c. WiFi is very close to 0.99c

Joe