L6 mecse ncc

VIT

N
Lecture : 05
C
Sub: Net-Centric Computing
C
Unit 01 : OSI Model

Class : ME CSE(Info.Tech)

Date : 21/08/2007

Delivered By
Manik Dhore

April 23, 2012 M.E. CSE-IT/NCC 1

VIT

N
C
C I need no warrant for being,
and no word of sanction upon my being.
I am the warrant and the sanction


VIT What OSI Defines ?

 How n/w devices contact each other?
N
 Methods by which device knows when to transmit data and when
C not to
C  Methods to ensure that n/w transmission is received correctly and
by the right recipient

 How to ensure that network devices maintain a proper DTR of
data flow ?

 How bits are represented on the n/w media ?

 How to sequence the layers with Connection / Connectionless?

 How to organize network functions into seven layers ?

 How to organize peer to peer mode ?

VIT Design Issues of Protocol Layers

N  Mechanism for identifying sender and receiver
C I.e. Addressing

C  Rules for Data Transfer
Unidirectional ( Simplex )
Bi-directional ( Half and Full Duplex)
 Methods for Error Control :
Error Detection
Error Correction
 Queuing mechanism for Fast Sender and Slow Receiver

 Methods to process arbitrarily long messages


VIT

 Algorithms for Route decisions
N  Multiplexing and demultiplexing for multiple connections
C Centralized

C Decentralized
Dynamic
 Logical decompositions of complex network

 Standard interfaces between n/w layers

 Symmetry in functions

 Standard communication network language

VIT

 Link approach
N  Connection Oriented
C  Connectionless

C Connection Oriented Means
iv. Acknowledgment
v. Flow Control
vi. Error Control

Connectionless Means
 No Acknowledgment
 No Flow Control
 No Error Control


VIT

N
C Happiness is that state of consciousness
C which
proceeds from the achievement of one's values.


VIT OSI Model

N
C 7. Application 1. Application
6. Presentation 2. Presentation
C
5. Session 3. Session
4. Transport 4. Transport
3. Network 5. Network
2. Data Link 6. Data Link
1. Physical 7. Physical


VIT Application Layer
 provides network services to application processes
( such as electronic mail, file transfer,terminal emulation )
N
 Interface to TDI or Third Party
C
 Gateways for different network file formats
C

Presentation Layer
 Data representation
 Format of data
 Data structures
 Ensure data is readable by receiving system
 Negotiates data transfer syntax for application layer.
 Resolves differences between format

VIT Session Layer
 Interhost communication

N  Establishes, manages and terminates sessions between
applications
C
 Controlling dialogues between applications in the end
C systems
 Dialogue discipline, Grouping and Recovery

 Ex.
 Logging Process
 Remote Terminal Access in half duplex
 Transaction Processing checkpoints, backups
Token management in half duplex mode


VIT Transport Layer
 End-to-end connection reliability
N  Concerned with data transports issues between hosts
C  Data transport reliability
C  Establishes, maintains, terminates virtual circuits. /
multiple network connections

 Fault detection and recovery / Error Control

 Flow control management

 Error free delivery of data

 Fragmentation and reassembly ( into packets as per
network layer specification )

 Decision about service type


VIT Network Layer
 Addresses Resolution

N  Controlling Subnet
 Providing best path
C
 Provides connectivity and path selection between two end
C systems
 Domain of routing / Route decision and selection
 Congestion Control Mgt.
 Accounting
 Large Packet Mgt.
 Heterogeneous n/w problem mgt
 Determines Quality of Service


VIT Data Link Layer
 Access to media
N
 Provides reliable transfer of data across media.
C
 Physical addressing, network topology, error notification,
C flow control.

 Framing : Break packets into frames according to the
specifications of physical layer standard I.e encapsulation
and de-capsulation of data

 Error Control and Recovery for physical Channel

 Link Management

 Collision Avoidance and collision content resolution


VIT Physical Layer
 Binary transmission
N  Wires / Cables
C  Connectors

C  Voltages

 Data rates

 Initial Connection

 Turn down connection

 Pin assignments

 Concentrators / Hubs/ Repeaters

 Wiring Schemes


VIT

N
C
C

Don't fall before you're pushed


VIT Needs of DOD
 Ability to connect multiple networks ie homogeneous as well
as heterogeneous ( Internetworking )
N
C  Network must be able to survive the loss of subnet hardware
C
 Multiple transmission lines

 Connectionless services

 Real Time Speech Transmission


VIT TCP / IP Model

N
C 4. Application
3. Host to Host
C
2. Internet
1. Network Access Layer


VIT OSI TCP/IP
ISO in 1977 and adopted in DoD in 1974 by Vint Cerf &
1983 Robert Kahn
N
C Developed by dedicated team Developed by open process
C
Copyrighted and carry a Free
Purchase fees

Proprietary Non-proprietary

Intended to be a Inter- Never indented to be
National standard

Designed with layers Not designed with layers

VIT OSI TCP/IP
Devised first and protocols Protocol came first and then
Invented latter model
N
C Seven Layers Four Layers
C
T-Layer is connection Both- less and oriented

N/w –Layer is both N/w layer is connection
oriented
Gives interface,service No clear distinction
And protocols

Generalized Not Generalized


VIT OSI TCP/IP
Strongly describes protocol Poorly describes protocol
stack stack
N
C Separate Layers Can view in layers
C
Not Popular Very Popular


VIT TCP/IP Network Components

N
C FTP, Telnet, POP TFTP, DNS, BOOTP
C SMTP,FINGER,HTTP SNMP,NFS

TCP UDP

ICMP ARP
RARP IP OSPF
RIP X.25 Packet Level

VIT TCP/IP Model

N
C
C


VIT TCP
 Port Numbers

N  32-bit Sequence Number
 32-bit Ack Number
C
 Flags : URG, ACK, PSH, RST, SYN, FIN
C
 Urgent Pointers
 Connection Oriented
 Reliable
 Full Duplex
 ID Assignment to multiple virtual circuits
 Works with IP
 Maintain the sessions


VIT TCP Header

N
C
C


VIT UDP

 Provides a lossy connection (data may vanish).
N
 Does not guarantee packets are delivered in order.
C
C  Useful for real time applications.

 UDP applications can implement their own packet loss
checking but it is best to use TCP for this.


VIT UDP Frame Format

N
C
C


VIT IP
 Connectionless

N  Unreliable
 Uses only packet switching
C
 TOS : Priority, Delay, Throughput, Reliability
C
Satellites and Leased Lines
 Flags : DF and MF
Don’t and More
 TTL : Number of hops ( If not delivered return
to)
 Protocol : Application Layer
 Padding
 Offset of fragment
 Packet Size : 64 K

VIT IP header

N
C
C


VIT ICMP
 Internet Control Message Protocol packets are used for
N various control purposes. Here are some common ones:

C  Time exceeded: TTL hit 0.
C  Echo request: Can you hear me out there?

 Echo reply: Yes I can hear you.

 Source Quench: Stop sending so much data.

 Timestamp request/reply (as echo but with times).


VIT
Netware IPX/SPX Network Component
N
C
C SAP NLSP File Server
NCP RIP
SPX

IPX

LSL MLID ODI


VIT

N
C
C


VIT
Netware Suite
N  Proprietary Protocol Suite
C
C  Developed by : Xerox Network System

 IPX : Internetwork Packet Exchange

 SPX : Sequenced Packet Exchange

 Modular in nature

 Architecture is server – centric

VIT IPX
Connectionless datagram service
N Broadcast mechanism for error notification and time
C synchronization

Dynamic route selection
C
Transport Control : Max 16 bridges using counter

Packet Type : 0x8035

Destination Address : 12 bytes

 Network Number – 4 bytes

 Node Address -- 6 bytes

 Socket Number -- 2 bytes

Data in packets : 546 bytes


VIT

Microsoft NetBIOS/ NetBEUI Network Components
N
C
C
File I/O Named Pipes Redirector Server Mail slots

NetBIOS Sockets SMB

NetBEUI

NDIS

VIT NETBIOS
(Network Basic Input Output System)

N •NetBios is also a session/transport layer protocol

C • Starting and stopping sessions.

C • Name registration

• Session layer data transfer(reliable)

• Datagram data transfer(unreliable)

• Protocol driver and network adapter management
functions

1) nbstat -n Lists all registered NetBios names.
2) nbstat -c Shows the NetBios cache.
3) nbstat -R Reloads the NetBios name cache from the
lmhosts file.

VIT NetBEUI
NetBIOS Extended User Interface

N
 Basically Transport Layer Protocol
C
C
 Performance in LAN environment is very good

 Requires small amount of configuration

 Requires small amount of resources (Memory)

 Can handle maximum 254 sessions


VIT Books
Lecture 01/02/03/04/06 :

N 3. Tananbaum :
Computer Networks PHI De Facto Standard
C
2. High Speed Networks and Internet PHI
C
3. ISDN Broadband ISDN with Frame Relay and ATM
Pearson
4. Data Communication and Networking by
Forouzan Edition 2 and 3 , TMH
Short questions and answers


VIT
5. Data and Computer Communication by William Stalling
N 4th and 6th edition PHI
6. Network Communication Technology by Elahi
C
Thomson Pub, Short questions and answers
C
7. An Introduction to Computer Networking by
Mansfield and Antonakos, Pearson Education
8. Building Practical Ethernet Networks BPB
9. Internetworking By Miller
10. Networking Devices by Miller


VIT
11. Telecommunications Network Design Algorithms by
Kershanbaum A. TMH
N
12. Comer : Computer Networks Vol.1, 2 and 3
C 13. TCP/IP Illustrated By Steven Vol. 1,2 and 3
C 14. IP Telephony by Douskails B. Pearson

And N- number of cited web references


VIT
1. Write a Client – Server program for ping by building your own
packets. ( Individual) ( c-Language) ( Time 1 week)
N
2. Design a sniffer for windows by using packet driver and calculate
C the bandwidth utilization ( protocolwise) of your network
3. Design a configurable firewall for windows(VB)
C
4. Develop a simulation software to simulate working of Frame Relay
5. Develop a simulation software to simulate working of ATM
6. Develop a simulation software to simulate working of ISDN
7. Develop a package for the following compression methods
I) Run length Encoding ii) Facsimile Compression
iii) String Matching iv) Wavelet Compression
v) JPEG
Note : Assignment 2-7 are group assignment
Team Size is 5 ( According to roll number)

VIT Practical Guidelines
Assignment No.1 :

N •TCP/IP Illustrated by Steven Vol.1,2 and 3
•Simple Client Server
C
•Use of RAW Sockets
C
•Building of ICMP Packets


VIT
Assignment No.2 :
N Sniffer ( Study Ethereal First)
C Download Packet Driver

C Install it
Use the driver services
Map the data


VIT
Assignment No.3 :
N Firewall
C Download Packet Driver

C Install it
Use the driver services
Configure the ports
Map the data


VIT
Assignment No.4,5,6 :
N Frame Relay
C Study Frame Use Operations

C Use Java , JavaScript, JSP
Simulate Protocol Operations


VIT
Assignment No.7 :
N Compression
C Plenty books are available

C


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