A network consists of devices called nodes that are connected by communication links. Most networks use distributed processing, where the task is divided among multiple computers rather than one large computer. A network must meet criteria like performance, reliability, and security. Performance is measured by factors like transit time, response time, throughput, and delay. Reliability looks at frequency of failures and recovery time. Security involves protecting data from unauthorized access and damage. Networks can have either point-to-point connections between two devices or multipoint connections where more than two devices share a single link.

1. Network

2. Network
• A n/w is a set of devices (often referred to as
node) connected by communication links.
• A node can be a computer, printer, or any
other devices capable of sending or receiving
data generated by other node s on the n/w.

3. Distributed Processing
• Most n/w’s are distributed processing , in
which the task is divided among multiple
computers.
• Instead of one large single machine being
responsible for all aspects of a process,
separate computers ( usually a pc, or a
workstation) handle a subnet.

4. Network Criteria
• A n/w must be able to meet a certain number
of criteria.
• The most important of these are
• Performance
It can be measured in many ways, including
transit time and response time.
Transit time is the amount of time required
for a message to travel from one device to
another.

5. • Response time - it is the elapsed time
between an enquiry and a response.
• The performance of a n/w depends on the
number of factors including no. of users , the
type of transmission medium, the capabilities
of the connected hardware and the efficiency
of the software.

6. • Performance is evaluated by two networking
metrics : throughput and delay.
• We often need more throughput and less
delay.
• These two criteria are contradictory .
• If we try to send more data , it may increase
the throughput , but increases the delay.

7. Reliability
• In addition to accuracy of delivery, n/w
reliability is measured in frequency of failure.
• The time it take to recover from a failure.

8. Security
• N/w security issues include protecting data
from unauthorized access , protecting data
from damage and development , and
implementing policies and procedures for
recovery from losses .

9. Type of connections
• A network is two or more devices connected
through links.
• A link is a communications pathway that
transfers data from one device to another.
• There are two possible types of connections:
• Point-to- point , Multipoint

10. Point-to-point
• A point-to-point connections provides a
dedicated link between the two devices .
• The entire capacity of the link is reserved for
transmission between the two devices.

11. Multipoint connection
• A multipoint connections is one in which more
than two specific devices share a single link .