Computer networking

1. NAME:-SHIVANGI
DEPT:- COMPUTER SCIENCE & ENGINEERING
ROLL NO:- ‘9’
GROUP:- ”X”
TOPIC NAME:- “Computer
Networking”
SUBMITTED TO:-

2. Communication between applications on
different computers.
Must understand application needs/demands.
Traffic data rate.
Traffic pattern (bursty or constant bit rate).
Traffic target (multipoint or single destination,
mobile or fixed).
Delay sensitivity.
Loss sensitivity.
What is the Objective of
Networking

3. Four Steps to Networking
Communicating across a link.
Connecting together multiple links
(internetworking).
Finding and routing data to nodes on
internetwork.
Matching application requirements.

4. A First Step
Creating a link between nodes.
Link: path followed by bits.
•Wired or wireless.
•Broadcast or point-to-point (or
both).
Node: any device connected to a
link.

5. 5
Types of Links
Point-to-Point Multiple Access
…

6. 6
Switched Network
What are Switched Networks
 Switch: moves bits
between links
 Packet switching
 Circuit switching

7. 7
Packet Switching (Internet)
Packets

8. 8
Packet Switching
 Interleave packets from different sources.
 Efficient: resources used on demand.
 Statistical multiplexing
 General
 Multiple types of applications.
 Accommodates bursty traffic.
 Addition of queues.

9. 1-9
Circuit Switching: FDM and TDM
FDM
frequency
time
TDM
frequency
time
4 users
Example:

10. 10
What if Network is Overloaded
Problem: Network Overload
 Short bursts: buffer
 What if buffer overflows?
 Packets dropped
 Sender adjusts rate until load = resources
 Called “congestion control”
Solution: Buffering and Congestion Control

11. 1-11
Why layering
Dealing with complex systems:
 explicit structure allows identification, relationship of
complex system’s pieces
 layered reference model for discussion
 modularization eases maintenance, updating of
system
 change of implementation of layer’s service
transparent to rest of system
 e.g., change in gate procedure doesn’t affect
rest of system
 layering considered harmful

12. 1-12
Internet protocol stack
 application: supporting network
applications
 FTP, SMTP, HTTP
 transport: process-process data
transfer
 TCP, UDP
 network: routing of datagrams from
source to destination
 IP, routing protocols
 link: data transfer between
neighboring network elements
 PPP, Ethernet
 physical: bits “on the wire”
application
transport
network
link
physical

13. 1-13
Network Security
 The field of network security is about:
 how bad guys can attack computer networks
 how we can defend networks against attacks
 how to design architectures that are immune to
attacks
 Internet not originally designed with (much)
security in mind
 original vision: “a group of mutually trusting
users attached to a transparent network” 
 Internet protocol designers playing “catch-up”
 Security considerations in all layers!