Network Topology
Each
computer or device in a network is called a node. The arrangement or connection
pattern between nodes or systems and other devices of the network are known as
network topology.
- A
Network Topology is the arrangement with which computer systems or network
devices are connected to each other. Topologies may define both physical
and logical aspect of the network.
- Network
topology defines the structure of the network. One part of the topology
definition is the physical topology, which is the actual layout of the
wire or media. The other part is the logical topology, which defines how
the media is accessed by the hosts for sending data. Both logical and
physical topologies could be same or different in a same network.
- The
geometrical arrangement of computer system is called topology. There are
two different aspect of network topology. The physical topology describes
the actual physical layout or pattern of the cabling that connects the
nodes. The logical topology describes the path that signals take as they
flow through the network. The two don’t have to match exactly.
Bus Topology
Ring Topology
Star Topology
Mesh Topology
Hybrid Topology
Tree Topology
Bus topology
In bus
topology, all workstations are connected to a single communication line called
bus or common back bone. In this type of network topology, there is no central
node as in star topology. Computer and other devices are arranged in linear
format. Data are transmitted on the network through the back bone using the
computer destination address.
- Uses a cable as bus or
backbone to connect all nodes.
- Baseband or broadband
coaxial cable is used.
- If a part of bus fails, the
whole network fails.
- Adding an new node is
difficult.
- Fault diagnosis is
relatively difficult.
Ring topology
In a
ring topology computer are connected in the shape or a circle without any end
point. Each workstation contains two neighbors for communication or an input
and an output connection. The input connection of the workstation receives data
and transmitted to the next station through the output connection.
- Media failure on
unidirectional or single loop causes complete network failure.
- Relatively difficult to
reconfigure.
- It is difficult to
troubleshoot.
- The failure of one computer
can affect the whole network.
- Adding and removing
computers disrupts the network.
- A single node failure leads
to the collapse of the full network.
- Fault diagnosis is
difficult.
Star topology
- Uses a central hub to
connect the nodes to each other.
- Twisted pair, coaxial
cables or optical fiber cables are used.
- Failure of the central hub
will make the entire network collapse.
- Adding and removing a node
is relatively easy.
- Fault diagnosis is easy.
Mesh topology
In this
topology, all nodes are connected to each other. So, it is sometimes called
completely connected networks. In this topology, more cables are used and
linking cost depends on the number of nodes. This type of topology is very
reliable as any failure of one node will not affect communication between the
connected computers.
Hybrid topology
In
combination of two or more different topologies makes for a hybrid topology.
When two topologies are connected to one another, they do not display
characteristics of any one specific topology. This is when it becomes a hybrid
topology. It is chosen, when there is a need to use two basic working
topologies in place already and these have to be connected to one another. When
there is a connection of one topology to another topology, it still remains its
basic topology. However, when star topology and bus topology are connected to
one another, and gives rise to the creation of a central topology, then this is
called a hybrid topology. Often, when the topologies are connected to one
another, the layout of the resultant topology is difficult to comprehend. However,
the new topology works without any problems.
Tree topology
Tree
topology is a hierarchical computer network that is a combination of star and
bus topologies. It is the topology used for a large computer network for which
a star topology or ring topology is unsuitable due to the sheer scale of the
network. Tree topology divides the whole network into parts that are easily
manageable.
- Tree topology makes it
possible to have a point to point network.
- All computers have access
to their immediate neighbors in the network and also the central hub. This
kind of network makes it possible for multiple network devices to be
connected to the central hub.
- It overcomes the limitation
of star network topology, which has a limitation of hub connection points
and the broadcast traffic.
- It avoids limitation of a
bus network topology.
- Tree network provides
enough room for future expansion of a network.
Summary Chart
|
Physical
Topology |
Common
Cable |
Common
Protocol |
|
Linear Bus |
Twisted Pair, Coaxial, Fiber |
Ethernet |
|
Star |
Twisted Pair, Fiber |
Ethernet |
|
Tree |
Twisted Pair, Coaxial, Fiber |
Ethernet |
Architecture/Model of network
Architecture can be divided into three groups as follows:
Peer to Peer network
- In a peer to peer network,
there are no central authority figure, no network administration who
handles security, user accounts, passwords, management and so on. It can
take both a client and server role. There is no centralized control over
shared resources.
Client/Server model:
- The client server network
consist at least one server and one or more clients or workstations, where
user does their work. The server is the main computer which gives services
to the workstation. It stores and protects the user files and security of
entire network.
Centralized computing network
·
In
the centralized computing network, the main computer is called host computer.
Here, the workstation have no processing capabilities, they are just used for
input and output operations. The host computer runs and solves multiple jobs
for workstations in an efficient manner. It is run with a powerful operating
system called UNIX or Linux centralized computing is also called host based
network and it is still popular with large companies.
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“E" Explore different network types in our Types of Computer Networks post.”
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