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DISTRIBUTED COMPUTING

Sunita Mahajan, Principal, Institute of Computer Science, MET League of Colleges, Mumbai

Seema Shah, Principal, Vidyalankar Institute of Technology, Mumbai University

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Chapter - 2�Network Communication

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Topics

LAN and WAN technologies
Protocols for Network Systems
Asynchronous Transfer Mode
Protocols for Distributed Systems

VMTP (Versatile Message Transfer Protocol)
FLIP (Fast Local Internet Protocol)

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LAN and WAN Technologies

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Computer Network

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Classification of Networks

Based on number of interconnected nodes and type of communication link used

LAN
MAN
WAN
WLAN

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Evolution of network transmission speeds

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Interconnection of Networks

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WLAN

Allows to have network connectivity without the use of wires.
It uses infrared links, Bluetooth, low power radio signals.
Access point connected to LAN provide coverage up to 20m range with obstacles and 100m with clear line of sight.

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Classification of Wireless Networks

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Internetworks

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Wireless application protocols- WAP

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Protocols for Network Systems

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Protocols for network systems

Protocol is a formal set of rules and conventions that governs how computers exchange information over the network medium.
Protocol supports transparency
Protocols for networks

ISO/OSI
IP

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ISO/OSI Reference Model

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Functions of OSI layers

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Functions of OSI Layers

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Elements in layered service:

Service user
Service provider
Service Access Point (SAP)

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Control information in OSI layers

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Data encapsulation in OSI protocol data

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Internet Protocol

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OSI vs IP

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Major functions of the IP protocol

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Major functions of the IP protocol

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Major functions of the IP protocol

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TCP and IP layers at a glance

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Asynchronous Transfer Mode

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Introduction to ATM

ATM is connection oriented .
It supports voice, video and data communications.
It encodes data into small fixed - size cells.
Cells are suitable for TDM and transmits them over a physical medium.

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Introduction to ATM

Achieves fast speed by avoiding flow control and error checking.
It provides high bandwidth data transmission at a speed of up to

2.5 Gbps.

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ATM classification

ATM can be classified as CBR and VBR based on the type and volume of data transmitted.

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ATM virtual circuit

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ATM Reference Model

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ATM Layer functions

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AAL Layer

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ATM Standards

Standard A:

The User-Network Interface (UNI) standard contains the Generic Flow Control field (GFC) and Virtual Path Identifier (VPI) one-octet field.

Standard B:

The Network-Network Interface (NNI) has one and a half octets long VPI but does not contain the GFC field.

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ATM layer standards

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Functions of the ATM Layer field headers

Header Bit	Function
GFC	4 bits in the cell header Controls the amount of traffic entering the network All 0 s indicate uncontrolled cell so gets last precedence
VPI and VCI	VPI contains 8 bits and VCI contains 16 bit field in header Determines the path and channels for the cell to traverse
PTI	3 bits in header Distinguishes between data and control cells, which can be transmitted on different channels
CLP	1 bit in header When set, indicates that the cell can be discarded during congestion
HEC	8 bits in the header Contains the checksum of the header to protect from transmission errors

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ATM Adaptation Layers

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ATM Layer functions

Layer/Sublayer	Function
ATM adaptation layer Convergence sublayer Segmentation and reassembly sublayer	Convergence Segmentation and reassembly
ATM layer	Generic flow control Cell header generation/extraction Cell VPI/VCI translation Cell multiplex and demultiplex
Physical layer Transmission convergence sublayer Physical medium sublayer	Cell rate decoupling HBC header generation/check Cell delineation Bit timing Physical medium

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Protocols for Distributed Systems

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Protocols for Distributed Systems

VMTP-

Versatile Message Transfer Protocol

FLIP—

Fast local Internet Protocol

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Requirements of Distributed Systems

Transparency
Client server based communication
Group communication
Security
Network management
Scalability

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VMTP- Versatile Message Transfer Protocol

Supports request response behavior
Provides transparency
Group communication facility
Selective retransmission mechanism
Rate based flow control
VMTP server identify non idempotent operations and conditional delivery of real time communication.

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VMTP packet format

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VMTP client server interaction

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FLIP--Fast local Internet Protocol

Connectionless protocol and it provides

Transparency for process migration
FLIP Box
Uses one-way mapping
FLIP routes the packet from source NSAP to destination NSAP
Uses Calls for sending a message
Methods for secure delivery of message
Automatically handle network configuration changes

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FLIP box interface

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Summary

LAN and WAN technologies
Protocols for Network Systems
Asynchronous Transfer Mode
Protocols for Distributed Systems

VMTP
FLIP