COMPUTER COMMUNICATION NETWORKS AND INTERNET

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TEE 213/05
Telecommunication
Principles
Unit 5 COMPUTER COMMUNICATION
NETWORKS AND INTERNET
Semester January 2012

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Switch / Hub Users
•A hub is slower than the switch. The switch can
support up to 2
N
users without dividing the speed
by the number of users.
•The switch achieves this by quickly switching
between many users at the same time. This is
due to the assumption that not all computers will
be requesting for information at the same time.

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Example – Switch / Hub
•A 100Mb/s 8-port switch and a 100Mb/s 8-port hub are tested for 8
users. Calculate the speed that will be experienced by each user
when the:
–Switch is used
–Hub is used
•
•Switch = No degradation of speed will be experienced and each
user will experience 100Mb/s.
•Hub = Each user will experience a maximum surfing speed of
100Mb/s / 8 = 12.5Mb/s

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Mesh Configuration

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•Example
•Calculate the number of links that will be needed to link up 10
computers.

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Star Topology
•If the central computer (server) goes down, all communication
between computers ceases.
•This configuration is also speed-limited as all communications need
to pass through a single node (the server computer).

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Ring Topology

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Ring Topology Description
•In a ring topology, the server or control computer and all
computers are linked in a single close-loop.
•Usually data is transferred around the ring in only 1
direction, passing through each node.
•Therefore, there is some amplification and regeneration
of data at each node, permitting long distance
transmission distances between nodes.
•The ring topology can also be implemented at a low cost.
Expansion is also simple, as a new node can be easily
inserted into the ring network at any point.

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Bus Topology
In a Mesh topology, one node is connected to every other node. Every
node can talk directly to all other nodes. This arrangement is very
expensive and will cost more with the increase of computers in the
system, especially with wired connections.

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Advantages and disadvantages of each
topology

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Hierarchy of Networks

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Relationship with different
types of networks

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7-Layer OSI

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OSI Analogy

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The Packet Transmission
System

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TCP/IP
OSI layers TCP/IP layers
7. Application Application
6. Presentation
5. Session
4. Transport Host-to-Host (TCP)
3. Network IP
2. Data link Network access
1. Physical

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IPV4 Header

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IPV4 Address Classes

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Example
Given the company's network. Determine the Class of this network
From Figure, the router has address 202.178.0.1. Matching the net ID with
Table, this is a class C network.

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IPV4 addresses that cannot be
used
IP Address Reason why cannot be used
Default - Network 0.0.0.0 Refers to the default route. This route
simplifies routing tables used by IP
Loopback - Network 127.0.0.1 Reserved for loopback. The address
127.0.0.1 is often used to refer to the local
host. Using this address, applications can
address a local host as if it were a remote
host.
Network Address - IP address with all hosts
bits set to 0 (for example, 192.0.0.0)
Refers to the actual network itself. For
example, network 202.178.0.0 can be used
to identify network 202.178. This type of
notation is often used within routing tables
Subnet/network broadcast - IP address with
all node bits set to 1 (for example
202.178.255.255) (255 represents 1)
IP addresses with all node bits set to 1 are
local network broadcast addresses and must
not be used. Example: 125.255.255.255
(Class A)
Network broadcast - IP address with all bits
set to 1. Example: 255.255.255.255
The IP address with all bits set to 1 is a
broadcast address and must not be used.
These refer to all nodes in the network no
matter what the IP address.

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Example
•For a Class A network, calculate:
–The maximum number of networks
–The maximum number of valid hosts

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Thank you