Information Technology Reference
In-Depth Information
A
A
C
C
B
B
(a)
A
A
C
C
B
B
(b)
FIGURE 1.15
Comparison of circuit-switched networking and packet-switched networking.
(a) In a
circuit-switched network
, a single physical connection is established between the two
ends. The physical connection cannot be shared. In this illustration, one circuit links the two
computers labeled A, and another circuit links the two computers labeled B. The computers
labeled C may not communicate at this time, because no circuit can be established. (b) In
a
packet-switched network
, a message is divided into small bundles of data called packets.
Every packet has the address of the computer where it should be routed. If there is more
than one path from the message source to the message destination, different message
packets may take different routes. Packets from different messages may share the same
wire. In this illustration, three pairs of computers (labeled A, B, and C) are communicating
simultaneously over a packet-switched network.
sending computer and reassembling the packets at the receiving computer. IP (Internet
Protocol) is the set of rules used to route data from computer to computer. The
Internet
is the network of networks that communicate using TCP/IP. You could call January 1,
1983, the birth date of the Internet, because that was the date on which all ARPANET
hosts converted to TCP/IP.
