Chapter 15 – Part 2 Networks The Internal Operating System The Architecture of Computer Hardware and Systems Software: An Information Technology Approach 3rd Edition, Irv Englander John Wiley and Sons 2003 Wilson Wong, Bentley College Linda Senne, Bentley College
21
Embed
Chapter 15 – Part 2 Networks The Internal Operating System The Architecture of Computer Hardware and Systems Software: An Information Technology Approach.
This document is posted to help you gain knowledge. Please leave a comment to let me know what you think about it! Share it to your friends and learn new things together.
Transcript
Chapter 15 – Part 2 Networks The Internal Operating System
The Architecture of Computer Hardware and Systems Software:
An Information Technology Approach
3rd Edition, Irv Englander
John Wiley and Sons 2003
Wilson Wong, Bentley College
Linda Senne, Bentley College
Chapter 15The Internal Operating System – Part 2 – Networking
15.2-2
Network Basics Communication paths Protocol standards Data transmission
By character or byte at a time By sending the entire message at a time By subdividing the messages into packets and
sending each packet at a time Frames are packets that have been further
subdivided to meet requirements of the media access control hardware protocol
Chapter 15The Internal Operating System – Part 2 – Networking
15.2-3
Packet Header
Also known as the preamble Contains
Description of the packet Destination address of receiver Source address of sender Information about the data being sent
Chapter 15The Internal Operating System – Part 2 – Networking
15.2-4
Advantages of Packets Reduces communication overhead Reasonable unit for routing of data Alternative to dedicating a channel for the entire length
of the message Packets from several sources can share a single
channel Each sender/receiver pair appears to have a channel to
itself Receiving computer can process an entire block of data
instead of a character or byte at a time Simplifies synchronization of the sending and receiving
systems by providing clear start and stop points
Chapter 15The Internal Operating System – Part 2 – Networking
15.2-5
OSI Reference Model
Open Systems InterconnectionModel
Developed by International Standards Organization (ISO)
Contains seven layers
All People Seem To Need Data Processing
People Do Not Through Sausage Pizza Away
Application Presentation Session Transport Network Data Link Physical
Chapter 15The Internal Operating System – Part 2 – Networking
15.2-6
Layers of the OSI Model
Chapter 15The Internal Operating System – Part 2 – Networking
15.2-7
OSI Physical Layer
Responsible for transmission of bits Implemented primarily through
hardware Encompasses signaling method,
electrical and mechanical interfaces Example: RS-232, 10Base5
Chapter 15The Internal Operating System – Part 2 – Networking
15.2-8
OSI Data Link Layer
Responsible for error-free, reliable transmission of data
Frames sized for compatibility with the MAC protocol
Flow control, error detection and correction, retransmission
Uses MAC addresses
Chapter 15The Internal Operating System – Part 2 – Networking
15.2-9
OSI Network Layer Responsible for addressing and routing of
messages to final destination Breaks up messages into frames that meet
the requirements of intervening networks Local network – no routing
Physical address is appended to each packet Symbolic addresses are converted to physical
address through a lookup table External network – routing required
External tables are used to assist in routing message
Chapter 15The Internal Operating System – Part 2 – Networking
15.2-10
OSI Transport Layer Ultimate final address of destination is determined All end-to-end communication including intermediate
nodes
Chapter 15The Internal Operating System – Part 2 – Networking
15.2-11
OSI Session Layer
Establishes a dialogue between two applications or processes between systems
Terminates connection at end of session
Manages logins, password exchange, logoffs
Chapter 15The Internal Operating System – Part 2 – Networking
15.2-12
OSI Presentation Layer
Provides format and code conversion services
Examples File conversion from ASCII to Unicode Encryption, decryption Data reformatting Conversion between data formats used by
different email systems
Chapter 15The Internal Operating System – Part 2 – Networking
15.2-13
OSI Application Layer
• Provides utilities and tools for application programs and users
Chapter 15The Internal Operating System – Part 2 – Networking
15.2-14
TCP/IP Transmission Control Protocol/Internet Protocol Physical and Data Link layers are not specified by
the TCP/IP protocol Internet Protocol
Implemented in workstations and routers Messages are segmented into packets and are re-
assembled at the other end Uses IP for addressing and routing between networks
Transport Reliable end-to-end connectivity Final delivery of packets
Application
Chapter 15The Internal Operating System – Part 2 – Networking
15.2-15
TCP & UDP
Most TCP/IP applications use TCP for transport layer
TCP provides a connection (logical association) between two entities to regulate flow check errors
UDP (User Datagram Protocol) does not maintain a connection, and therefore does not guarantee delivery, preserve sequences, or protect against duplication
Chapter 15The Internal Operating System – Part 2 – Networking
15.2-16
Comparison of OSI and TCP/IP
Chapter 15The Internal Operating System – Part 2 – Networking
15.2-17
Network Services Protocol Stacks Sockets Network file transfers Print services Web services Messaging services Application program access to network services
RPC – remote procedure calls
Security and network management services Remote processing and login services
Chapter 15The Internal Operating System – Part 2 – Networking
15.2-18
Network File Transfers
FTP Internet file transfer protocol
Logical names for machine or drive Windows
Network files can be accessed transparently by being mounted directly into the current file system Unix / Linux
Chapter 15The Internal Operating System – Part 2 – Networking
15.2-19
Access for a Networked Operating System
Chapter 15The Internal Operating System – Part 2 – Networking
15.2-20
Network Systems
Distributed system Collection of independent computers that appear
to the users of the systems as a single computer
Client-Server system Control is centralized in the server computer Client computers have network access limited to
services provided by the servers
Peer-to-Peer system Any two computers can communicate with one
another within security constraints
Chapter 15The Internal Operating System – Part 2 – Networking
15.2-21
Copyright 2003 John Wiley & Sons
All rights reserved. Reproduction or translation of this work beyond that permitted in Section 117 of the 1976 United States Copyright Act without express permission of the copyright owner is unlawful. Request for further information should be addressed to the permissions Department, John Wiley & Songs, Inc. The purchaser may make back-up copies for his/her own use only and not for distribution or resale. The Publisher assumes no responsibility for errors, omissions, or damages caused by the use of these programs or from the use of the information contained herein.”