Date: Fall 2011
How do computers talk to each other?
Much like how we talk to each other, computers have a common
language. For most of us it's English. In addition, computers
follow what is called protocol, much like how we follow rules and etiquette.
The computer language is made up by an electrical signal and it is
either 5 volts or 0 volts. This can be represented as a  or a
. This one or zero is what is called a bit in the binary
language. Binary, meaning two bits of information.
The language can be defined so that  means "yes" and  means " no".
But computers can process multiple bits per given time. So adding
more bits, gives us more words. Say two bits of information: ,
, , . Each of these can mean "yes", "no", "maybe", "I
do not know".
Adding even more, say 3 bits, we get more combinations of bits and
hence more words:
 = no
 = yes
 = maybe
 = I do not know
 = start
 = stop
 = wait
 = ignore
So now we have a group of codes which are made up of binary information.
When computers talk to each other, they each have what is called an
address like your home address or much like a name. Pretend we have
more combinations of bits that will give us four names:
[Bob], [Mary], [Frances], [Tom].
We can now send a string of information that would say:
[Send to] [Sent from] [Command or message] [End of message]
So a conversation could look like this:
[Send to Bob] [Sent from Mary] [Hi Bob!] [End of message]
[Send to Mary] [Sent from Bob] [Good morning Mary!] [End of message]
[Send to Bob] [Sent from Mary] [Please call Frances and Tom] [End of message]
[Send to Mary] [Sent from Bob] [OK] [End of message]
[Send to Frances AND Tom] [Sent from Bob] [It's time for our
meeting!] [End of message]
Of course there are many rules and procedures that help maintain
conversations between computers, but the above is the basis for
communication between a switched-network of computers.
Hope that helps! Let me know if it does not.
Today, computers can talk to each other over metallic wires, fiber optic
cable or by radio link (called "wireless").
Tomorrow, who knows....
Computers use "protocols" that define the language that they speak to each
All computers on a network segment must speak the same language so they can
trade and understand each other's messages.
Computers are assembled in Local Area Networks (LAN) or Wide Area Networks
LAN connected computers connect to other computers in the local area, like
on the floor of a building, in a private residence, or in a department of a
WAN connects LANs to other distant LANs on the World Wide Web, or connect
branch offices to the central office or some other distantly connected LAN.
LAN protocols include:
Ethernet (Most used)
IEEE 802.11 wireless
Virtual LAN (VLAN)
WAN protocols include:
ATM (Asynchronous Transfer Mode)
MPLS (Multi-Protocol Label Service) (My favorite)
PPP (Point-to-Point Protocol)
OSPF (Open Shortest Path First)
BGP (Border Gateway Protocol) (Can be used on world-wide networks)
RIP (Routing Information Protocol)
...And you get the idea...
This is a whole career full of acronyms.
So if you want to start digging into it, there is an awful lot of
Start by Googling "LAN" and I would choose the Wikipedia sites, although
that is a steep start,
So you might be able to find other sites for beginners.
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Update: June 2012