[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

[ih] Internet addressing history section

On 2/16/19 10:56 PM, Joe Touch wrote:
> That sort of timeout isn?t as much the issue as the block coding that 
> helps reduce the impact of burst errors. It?s the size of the block that 
> often drives large delays in modems, even if they don?t ?wait? to be 
> filled up with data (I am not aware that they do or would - the blocks 
> go out on schedule, filled or not).

> Both are coax - although they vary, they?re both in that range.


> https://en.wikipedia.org/wiki/Velocity_factor
> TP varies - see the Cat 3, 5, 6, and 7 values.

I now have a reason, other than speed, to use something better than Cat 
5e in my house.  :-)

> Generally, yes. Open-ladder is the fastest for metal.

I'm quite familiar with Open Ladder line.  I've helped my dad build it 
more times than I can count.

> The 10 of 10base<something> **is** the 10 Mbps . Higher rates means 
> shorter bits; shorter bits means the *end* of the message arrives more 
> quickly, not the front of the first bit.


> The shortest Ethernet message (including preamble and SOF) totals 54 
> bytes, i.e., a transmission delay of 43.2 microseconds at 10 Mbps. The 
> propagation delay, even in a 1500ft cable (the longest possible), is 
> 1.875 microseconds (at 0.8c). In twisted pair the propagation delay is 
> 2.5 microseconds. The difference would be only 0.625 microseconds - or 
> about 1.4% of the transmission delay, not to mention other system delays.
> That would show up on a scope, but I doubt it would have been noticeable 
> within an operating system, e.g., due to scheduler granularity, etc.

Fair enough.

There could have also been an unknown problem that was different between 
my two tests.  I don't think I'm mis-remembering, but it's a possibility 
as that was probably 20+ years ago.

Grant. . . .
unix || die