Download Course Constitution: Computer Networks and Related Topics and more Slides Network Programming in PDF only on Docsity!
Day 1
Course Constitution
• Pre-reqs:
- Background in C
- Familiar with a UNIX based environment
• The books:
- Data and Computer Communications, William Stallings
- Unix Networking Programming Vol. 1, 2, Richard Stevens
- Computer Networks, A. S. Tanenbaum
Course Constitution – contd.
• Topics covered:
- Computer Networks
- Socket Programming
- System Programming
- TCP/IP advanced topics
- Advanced topics in computer networks
- Network Security, management, VoIP, QoS
The Plan
Topic # of Weeks
Computer Networks 2
Socket Programming 3
System Programming 2
TCP/IP Advanced 2.
Misc Topics in
Computer Networks
Communications Model
Source Txr
Transmission Medium Rxr Destination
Communication Tasks
• Transmission Medium Utilization
• Interface and Signal Generation
• Synchronization
• Exchange Management
• Addressing and Routing
• Message Formatting and Syntax
Protocol Architecture
• Protocol Tasks
- Path Activation for a particular destination
- Handshaking with destination
- Link management
- Application/Task specific requirements
Network Access Module Communication Network
File Transfer Application Communications Service Module Network Access Module
File Transfer Application Communications ServiceModule
Files and file transfer commands Communications-related messages
Protocol Layers
Application
Session
Presentation
Transport Network Datalink Physical
7 6 5 4 3 2 1
OSI Model
Application
TCP | | UDP IPv4, IPv Device driver and Hardware Internet protocol suite
Sockets
user process
kernel
applicationdetails
communicationdetails
Layers on OSI model and Internet protocol suite
OSI Architecture
The Seven Layers
• Physical layer
- the physical interface between devices and rules by which bits are passed from one to another
- mechanical, electrical, functional, procedural
• Data link layer
- activate, maintain, and deactivate link
- error detection and control
The Seven Layers contd.
Network layer
provides for the transfer of information between end systems across some sort of communications network network addressing
Transport layer
provides a mechanism for the exchange of data between end systems ensures delivery of data error free, no losses, in sequence connection-oriented , connectionless
The Seven Layers contd.
Session layer
lowest four layers: provide the means for the reliable exchange of data and provide an expedited data services some applications - control dialogue, backup and recovery provides the mechanism for controlling the dialogue between applications in end systems dialogue discipline - full duplex or half duplex grouping - define groups of data recovery - a check pointing mechanism
Signals
• Signal: Electric or electromagnetic
encoding of data
• Analog Signal: A continuously varying
signal that may be propagated over a
variety of medium.
• Digital Signal: A sequence of voltage
pulses that may be transmitted over a wire
medium.
Frequency Components
Modulation
• Modulation: Conversion of digital signal into
an analog signal
• Amplitude Modulation: Amplitude changes
with change in input
• Frequency Modulation: Frequency changes
with change in input
• Phase Modulation: Phase changes with
change in input
• Modem is used to convert digital signal into
analog signal and vice versa
Modulation schemes for digital
data
" Amplitude
Modulation
" Frequency
Modulation
" Phase
Modulation
" Bit Stream
Digital Encoding Schemes contd.
BW utilization: stream of 1s
5 bits = 5 microseconds
NRZI
1 1 1 1 1
Manchester
1 bit 1 micro sec
1 bit 1 micro sec
1 signal element .5 micro sec
Data Link Layer Functionality
• Framing
• Error Control
- Error Detection
- Error Correction
• Flow Control
Synchronization
• There exists a hierarchy of synchronization
tasks:
- Bit level : recognizing the start and end of each bit
- Character or byte level : recognizing the start and end of each character (or small unit of data)
- Block or message level : recognize the start and end of each large unit of data (in networks this is a frame).
Byte Stuffing (contd.)
STX Data ETX
STX A B ETX H W ETX
STX A B DLE ETX H W ETX
STX A B ETX H W ETX
Stuffed
Unstuffed
Before
Byte Stuffing (contd.)
STX Data ETX
STX A B ETX H DLE ETX
STX A B DLE ETX DLE DLE ETX
STX A B ETX H DLE ETX
Stuffed
Unstuffed
Before
Transmission Mode
• Synchronous Transmission: the complete
frame is transmitted as a contiguous string
of bits and the receiver tries to keep in
synchronism with the incoming bit stream for
the duration of the frame
• Asynchronous Transmission: Each character
(or byte) is treated independently for clock
(bit) and character (byte) synchronization
purposes and the receiver resynchronizes at
the start of each character received.
