COMPUTER NETWORKS
PLACEMENT PREPARATION [EXCLUSIVE NOTES]
SAVE AND SHARE WITH YOUR CONNECTIONS TO HELP THEM
Curated By- HIMANSHU KUMAR(LINKEDIN) https://www.linkedin.com/in/himanshukumarmahuri
Introduction To Computer Networks
Computer Network means an interconnection of autonomous
(standalone) computers for information exchange. The connecting
media could be a copper wire, optical fibre, microwave or satellite.
Networking Elements - The
computer network includes the
following networking elements:
1. At least two computers
2. Transmission medium either wired or wireless
3. Protocols or rules that govern the communication
4. Network software such as Network Operating System
Network Criteria:
The criteria that have to be met by a computer network are:
1. Performance - It is measured in terms of transit time and
response time.
• Transit time is the time for a message to travel from one device to
another
pg. 1 | HIMANSHU KUMAR(LINKEDIN)
, • Response time is the elapsed time between an inquiry and a
response.
Performance is dependent on the following factors:
• The number of users
• Type of transmission medium
• Capability of connected network
• Efficiency of software
2. Reliability - It is measured in terms of
• Frequency of failure
• Recovery from failures
• Robustness during catastrophe
3. Security - It means protecting data from unauthorized
access.
Goals of Computer Networks:
The following are some important goals of computer
networks:
1. Resource Sharing - Many organization has a substantial
number of computers in operations, which are located
apart. Ex. A group of office workers can share a common
printer, fax, modem, scanner etc.
2. High Reliability - If there are alternate sources of supply,
all files could be replicated on two or, machines. If one of
them is not available, due to hardware failure, the other
pg. 2 | HIMANSHU KUMAR(LINKEDIN)
, copies could be used.
3. Inter-process Communication - Network users, located
geographically apart, may converse in an interactive
session through the network. In order to permit this, the
network must provide almost error-free communications.
4. Flexible access - Files can be accessed from any
computer in the network. The project can be begun on
one computer and finished on another.
Other goals include Distribution of processing functions,
Centralized management, and allocation of network
resources, Compatibility of dissimilar equipment and
software, Good network performance, Scalability, Saving
money, Access to remote information, Person to person
communication etc.,
Transmission modes: -
Transmission Modes determine how data is transferred
between two devices in a computer network. There are 3
transmission modes in computer networks given below:
Simplex
Communication is uni-directional or one-way in Simplex Mode.
i.e. Only one device is allowed to transfer data and the other
device simply recieves it. e.g. Radio Station (The station
transmits and the radio only recieves).
pg. 3 | HIMANSHU KUMAR(LINKEDIN)
, Half-Duplex Communication is possible both-ways but not
simultaneously. i.e. Both the devices/stations can transmit and
recieve data but not at the same time. At an instant, only
communication in a single direction is allowed. e.g. Walkie-
Talkie.
Full-Duplex Bidirectional communication is possible
simultaneously. This can be possible in the following cases:
• Dedicated seperate channels for transmission and
reception
• Capacity is divided between transmission and reception
(if single channel is used)
pg. 4 | HIMANSHU KUMAR(LINKEDIN)
PLACEMENT PREPARATION [EXCLUSIVE NOTES]
SAVE AND SHARE WITH YOUR CONNECTIONS TO HELP THEM
Curated By- HIMANSHU KUMAR(LINKEDIN) https://www.linkedin.com/in/himanshukumarmahuri
Introduction To Computer Networks
Computer Network means an interconnection of autonomous
(standalone) computers for information exchange. The connecting
media could be a copper wire, optical fibre, microwave or satellite.
Networking Elements - The
computer network includes the
following networking elements:
1. At least two computers
2. Transmission medium either wired or wireless
3. Protocols or rules that govern the communication
4. Network software such as Network Operating System
Network Criteria:
The criteria that have to be met by a computer network are:
1. Performance - It is measured in terms of transit time and
response time.
• Transit time is the time for a message to travel from one device to
another
pg. 1 | HIMANSHU KUMAR(LINKEDIN)
, • Response time is the elapsed time between an inquiry and a
response.
Performance is dependent on the following factors:
• The number of users
• Type of transmission medium
• Capability of connected network
• Efficiency of software
2. Reliability - It is measured in terms of
• Frequency of failure
• Recovery from failures
• Robustness during catastrophe
3. Security - It means protecting data from unauthorized
access.
Goals of Computer Networks:
The following are some important goals of computer
networks:
1. Resource Sharing - Many organization has a substantial
number of computers in operations, which are located
apart. Ex. A group of office workers can share a common
printer, fax, modem, scanner etc.
2. High Reliability - If there are alternate sources of supply,
all files could be replicated on two or, machines. If one of
them is not available, due to hardware failure, the other
pg. 2 | HIMANSHU KUMAR(LINKEDIN)
, copies could be used.
3. Inter-process Communication - Network users, located
geographically apart, may converse in an interactive
session through the network. In order to permit this, the
network must provide almost error-free communications.
4. Flexible access - Files can be accessed from any
computer in the network. The project can be begun on
one computer and finished on another.
Other goals include Distribution of processing functions,
Centralized management, and allocation of network
resources, Compatibility of dissimilar equipment and
software, Good network performance, Scalability, Saving
money, Access to remote information, Person to person
communication etc.,
Transmission modes: -
Transmission Modes determine how data is transferred
between two devices in a computer network. There are 3
transmission modes in computer networks given below:
Simplex
Communication is uni-directional or one-way in Simplex Mode.
i.e. Only one device is allowed to transfer data and the other
device simply recieves it. e.g. Radio Station (The station
transmits and the radio only recieves).
pg. 3 | HIMANSHU KUMAR(LINKEDIN)
, Half-Duplex Communication is possible both-ways but not
simultaneously. i.e. Both the devices/stations can transmit and
recieve data but not at the same time. At an instant, only
communication in a single direction is allowed. e.g. Walkie-
Talkie.
Full-Duplex Bidirectional communication is possible
simultaneously. This can be possible in the following cases:
• Dedicated seperate channels for transmission and
reception
• Capacity is divided between transmission and reception
(if single channel is used)
pg. 4 | HIMANSHU KUMAR(LINKEDIN)
