Broken Any Records Lately?

Sometimes we seem obsessed with superlatives:  farther, faster,
better....  Lately, I started thinking about the capacities of
personal computers I've used.  Here's a
quick chronological summary of my recollections:

-----------|--------------|--------------------
           | Primary 	  |Secondary 
Machine	   | Memory	  |Memory
-----------|--------------|--------------------		
  mini     |  2048 words  |1000 512-word blocks
	   |(12 bits/word)|(magnetic tape reel)
-----------|--------------|--------------------		
  286	   |  1024 KB	  |  10 MB
-----------|--------------|--------------------		
  386	   |    4 MB	  |  128 MB
-----------|--------------|--------------------		
  486      |   20 MB	  |  250 MB
-----------|--------------|--------------------		
  Pentium  |   40 MB	  |  800 MB
-----------|--------------|--------------------		
Pentium/MMX|   48 MB	  |  2.1 GB
-----------|--------------|--------------------

Although digital computing has taken huge strides, constantly setting 
and then resetting records, this has never been satisfactorily explained.
It was noticed and formulated in one way over twenty years ago as 
Moore's Law by Gordon Moore, cofounder of Intel.  Moore  predicted that 
the number of transistors on a microprocessor would double approximately 
every 18 months, with speed and memory also improving similarly.
This prediction has proved quite accurate ever since.

Like computing, communications technology has also improved explosively, 
partly because it depends in part upon computing.  For example, routers and 
switches used to connect data comm networks are nothing more than specialized 
computers themselves, so it seems reasonable that networking should progress as 
computers progress.  If communications is like computing, then what records 
can be cited for comunications?  What are the current records for telecomm 
and data comm?  Some recent examples of each are offered below.


LAN Record:  1 Gb/s

Most business computers are attached directly to a Local Area Network (LAN), 
usually either an Ethernet or a Token Ring.  The LAN, in turn, 
is connected to other computers and LANs through devices called switches and 
routers.  Switches and routers connect LANs to each other, using Wide Area 
Networks (WANs) where necessary.  The maximum distance serviced by a LAN depends 
on a number of technical factors, including the type of interface, the type of 
wire, wire speeds used, etc.  Typical maximum distances run from a few hundred 
to a few thousand feet.

	Ethernet was developed beginning in the early 1970s and has been refined 
many times since then.  Original transmission speeds were 10 Megabits per 
second, but now there is Fast Ethernet with 100 Mb/s.  Gigabit Ethernet 
(1,000,000,000 or 1 billion bits per second) is still in the IEEE 802 standards 
committee, but already Gigabit products are available in the market.  Token Ring 
was introduced by IBM with first 4Mb/s and then 16Mb/s transmission speeds.  

	Both Ethernet and Token Ring started as shared media systems, which means 
that all computers attached to the LAN had to share the cables or hubs by taking 
turns.  This meant that at most only one computer could send at one time, so all 
the other attached computers had to wait their turns.  Recently switched LANs 
have been developed, so that several computers can be transmitting 
simultaneously at the maximum transmission or wire speed.  Thus, a very high 
aggregate or effective speed (N times wire speed, where N is the number of 
simultaneous transmitters) can be attained.  


WAN Record:  39.81 Gb/s

	Wide Area Networks use technologies different from those of the LAN in 
detail, but virtually identical in concept.  Individual networks use their own 
specific formats so that the transmitters and receivers can understand each 
other, but they all ultimately send a serial bit stream from one computer to another.

	WANs use interfaces that support wire speeds as low as 300 bits per 
second, and escalate to the familiar T-1 (1.544 Mb/s) and T-3 (44.736 Mb/s) on
metal cables.  Since the advent of fiber optic connections, the transmission speeds 
have leaped up to set new records again, and in fact a new system used to gauge these 
speeds is based on multiples of the Optical Carrier (OC-1) speed of 51.84 Mb/s.

	In terms of optical carrier speeds, the record-fast WAN connection that I 
know of at this moment is an MCI link between Chicago and St. Louis designed to 
handle OC-768 traffic.  This means it will accommodate 39.81 Gb/s, or almost 40 
Gigabits/second.

Lessons

	We can expect that all networks will continue to increase in speed for the 
foreseeable future.  (Let me know if you find faster records with E-mail to
cshinn@compututor.com)  We must continue to take advantage of the better 
technologies as they arrive, as they become cost effective.  No wonder it is often 
better to rent computing and communications equipment than to buy it.