Page 77 - DCAP406_DCAP_207_Computer Networks

Computer Networks/Networks

Notes  This is manageable via SNMP (Simple Network Management Protocol) or another
appropriate network management protocol.

 Switching hub provides an expanded bandwidth.
Self Assessment

Name the following:
1. A place of convergence where data arrives from one or more directions and is forwarded
out in one or more other directions.

2. A device that allows network administrators to segment their networks transparently.
3. A device that incorporates bridge functions as well as point-to-point ‘dedicated
connections’. They connect devices or networks, filter, forward and flood frames based on
the MAC destination address of each frame.
4. Devices used to connect two devices at the network layer of the OSI Model.
5. Devices that are used to connect totally dissimilar networks because they can perform
protocol conversion for all seven layers of the OSI Model.

5.6 Switching Techniques

An Ethernet can connect up to only 1024 hosts within a span of only 1500 meters. Therefore, the
LAN technologies are not sufficient for building a global network and interconnecting hosts of
other networks. In a telephone exchange, a switch provides connection between called and
calling party without providing direct line-to-line connection between them. The telephone
network uses circuit switching that provides dedicated channel between called and calling party
while computer networks use packet switching that does not provide a dedicated channel between
the hosts. Figure 5.13 attempts to explain switching technique where any computer may exchange
information with any other computer. A switch is used to interconnect different hosts to its
several inputs and outputs. The functions of a switch are store and forward, routing and congestion
control that are required to accomplish interconnection. The switching techniques enable us to
build a MAN or WAN or Internet.
Think how things would be if you could only use your telephone to talk to just one other person!
You would not be very productive. So there are requirements for switching systems to route
your calls around the world.

There are a number of ways to perform switching:
 Circuit Switching
 Packet Switching
 Message Switching

 Cell Switching

5.6.1 Circuit Switching

The circuit switching technique provides a dedicated physical communication path from source
to destination terminal within a network. Therefore, a dedicated bandwidth is created, maintained
and terminated for each communication session. The circuit switching session, thus comprises
of 3 phases like circuit establishment, data transfer and circuit disconnect. Prior to the data

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