04/10/23
Find 10’s complement of 52520 using quick way.
rn– N = ( rn – 1 ) – N + 1 _________A
From equation A,10’s complement is just equal to the 9’s complement plus 1.
So, for 9’s complement of 52520,The result using quick way is 47479
10’s complement is 47479 + 1 = 47480
However, we can also find the 10’s complement by leaving all least significant 0’sunchanged, subtracting the first non-zero least significant digit from 10 and subtracting alhigher significant digits from 9. So, using the assumption above,
10’s complement of 52520 is 47480
Find 10’s complement of 52520 using quick way.
rn– N = ( rn – 1 ) – N + 1 _________A
From equation A,10’s complement is just equal to the 9’s complement plus 1.
So, for 9’s complement of 52520,The result using quick way is 47479
10’s complement is 47479 + 1 = 47480
However, we can also find the 10’s complement by leaving all least significant 0’sunchanged, subtracting the first non-zero least significant digit from 10 and subtracting alhigher significant digits from 9. So, using the assumption above,
10’s complement of 52520 is 47480
Open Systems Interconnection (OSI) Open Systems Interconnection (OSI) Reference Model for Networking Reference Model for Networking
COSC 513 Operating SystemsCOSC 513 Operating Systems
Instructor : Dr. Mort AnvariInstructor : Dr. Mort Anvari
Presented Presented by by
Cheng Chiang GohCheng Chiang Goh
ObjectiveObjective
The aim of this topic is to understand theoretical models for what networks are and how they work. The Open Systems Interconnection (OSI) reference model for networking, which explains how networks behave within an orderly seven-layered model for networked communications.
IntroductionIntroductionThe concept of networking is so essential in this fast-moving
world nowadays, for the purpose of sharing information and
resources. Open Systems Interconnection (OSI) reference
model proposed by the International Standards Organization
(ISO) has been so successful to create an intellectual
framework within which to clarify network concepts and
activities. Today, OSI reference model has become a key
part of networking. The IEEE 802 is an enhancement to the
OSI model. With OSI model, networking can be broken into
seven layers. Therefore, the complexity of networked
communications, from application to hardware is broken into
a series of interconnected tasks and activities. It creates a
method to solve big problem by deconstructing them into a
series of smaller problems, that can then be solved
individually.
TopicsTopics Open Systems Interconnection (OSI) Model IEEE 802 Model OSI Reference Model Structure Network Communications and Protocols in OSI
model Protocols in Layered Architecture TCP/IP Protocol
Devices at each OSI model
OSIOSI ModelModel Layer 7 AApplication Layer 6 PPresentation Layer 5 SSession Layer 4 TTransport Layer 3 NNetwork Layer 2 DData Link Layer 1 PPhysical
PProgrammers DDo NNot TThrow SSausage PPizza AAway
Layer 7Layer 7 ApplicationApplication Top layer of OSI model provides interfaces for application to obtain access to
networked services Services like file transfer, message handling, database
query processing Also handle general network access: movement of data
(flow control), error recovery Transfer information from program to program
LayerLayer 6 6 PresentationPresentation Handles data format for networked
communications ( outgoing and incoming messages)
protocol conversion, data encryption and decryption as well as graphics commands
compress data for transmission to reduce the volume of data ( then decompression)
Redirector (software facility)
Layer 5Layer 5 SessionSession Permits two parties to hold ongoing communication
across a network handles session setup, data or message exchanges
and tear-down when session ends permit only authorized parties to establish session
(security)
Layer 4Layer 4 TransportTransport Manages the conveyance of data from sender to
receiver across a network segment long data into chunks that match the
maximum packet size for networking medium acknowledges successful transmission and request
retransmission when packets do not arrive it make sure that long data payloads make their
destination across the network
Layer 3 Layer 3 NetworkNetwork Handles addressing messages for delivery translates logical network addresses and names into
their physical counterparts decides how to route transmissions from sender to
receiver also handles packet-switching, routing and congestion
control Fragmentation and Reassemble ( from dissimilar
media - downsizes packets
Layer 2Layer 2 Data LinkData Link
Sends data frames from Network layer to Physical Layer [data frame consists of destination ID, sender ID, control, data and CRC(cyclical redundancy check-mathematical function based on bit patterns)]
adds error-checking information and formats data for physical transmission
Layer 1Layer 1 PhysicalPhysical Its jobs is to convert bits into signals for outgoing
messages and via versa manage hardware connection cable, transmitter, receiver, repeater operate at this
layer.
IEEE 802 extensions to the OSI IEEE 802 extensions to the OSI reference modelreference model
Layer 7 Application Layer 6 Presentation Layer 5 Session Layer 4 Transport Layer 3 Network Layer 2 Data Link -----Logical link control
-----Media access control
Layer 1 Physical
IEEE 802 standard breaks the Data Link layer into two sublayer
Logical Link Control (LLC) Also known as IEEE 802.2 for error control correction and flow control
Media Access Control (MAC) for access control direct access with NIC and ensure error-free data
transmission
802.3 CSMA/CD 802.4 Token Bus 802.5 Token Ring 802.12 Demand Priority
Network Communications and Protocols Network Communications and Protocols in OSI modelin OSI model
Protocols are rules and procedures for communications many protocols used today TCP/IP, NetBIOS/, IPX/SPX,
AppleTalk, the higher the protocols in the OSI model or layer, the
more sophisticated the protocol is protocol stack TCP/IP, the Internet protocol suite,
IPX/SPX for Novell NetWare
Two methods of delivering data in a network
Connectionless fast but not reliable
(don’t waste time to establish, manage and tearing down connections)
Connection-Oriented slower but reliable
Network layer of the OSI model is responsible for moving data across multiple network
Routable Network Layer (4) protocols like TCP/IP,
IPX/SPX; suitable for large network
Nonroutable NetBEUI; for small
network
Protocols in a Layered ArchitectureProtocols in a Layered Architecture Layer 7 Application Layer 6 Presentation Application
Layer 5 Session Protocol
Layer 4 Transport Transport
Protocol
Layer 3 Network Layer 2 Data Link Network Layer 1 Physical Protocol
Network ProtocolsNetwork Protocols Provide addressing and routing information, error
checking, retransmission requests and rules for communicating in a particular networking environment
Protocols likes IP (Internet Protocol) IPX (Internetwork Packet eXchange and NWLink NetBEUI DDP (Delivery Datagram Protocol) DLC (Data Link Control)
Transport ProtocolsTransport Protocols Ensure reliable data delivery between computers
Protocols likes TCP (Transmission Control Protocol) SPX (Sequenced Packet eXchange) and NWLink NetBEUI/NetBIOS ATP (AppleTalk Transaction Protocol) and NBP (Name
Binding Protocol)
Application ProtocolsApplication Protocols Provide application-to-application services
Protocols likes SMTP (Simple Mail Transport Protocol) FTP (File Transfer Protocol) SNMP (Simple Network Management Protocol) NCP (NetWare Core Protocol) AFP (AppleTalk File Protocol)
OSI ModelOSI Model TCP/IP ProtocolTCP/IP ProtocolStackStack
Layer 7 Application Layer 6 Presentation Layer 5 Session
Layer 4 Transport
Layer 3 Network
Layer 2 Data Link
Layer 1 Physical
TelnetFTP
SMTP
TCP DNS UDP
IP ICMP ARP OSPF RIP
ODI or NDIS
NIC Driver
Physical Connection
TCP/IPTCP/IPAllows for easy cross-platform communications and is the
basic for Internet ICMP (Internet Control Message Protocol) --- network layer;
used to send control messages ARP (Address Resolution Protocol) --- network layer; used
to associate a logical IP address to a physical MAC address
TCP (Transmission Control Protocol) --- transport layer; connection-oriented; transport protocol
UDP (User Datagram Protocol) --- transport layer; connectionless; faster than TCP
DNS (Domain Name System) --- transport layer; name-to-address resolution protocol (for example www.Microsoft.com to 102.211.10.111)
FTP ( File Transfer Protocol) --- session, presentation and application layer; provides services for file transfer as well as directory and file-manipulation services
Telnet --- remote terminal emulation protocol; used to provide connectivity between dissimilar system
SMTP (Simple Mail Transport Protocol) --- used for messaging services and is the basic for e-mail across Internet
(RIP) Routing Information Protocol --- a distance-vector protocol used for route discovery
OSPF (Open Shortest Path First) --- a link-state routing protocol; used to determine the best path through a network
IP (Internet Protocol) --- network layer; responsible for addressing and routing; (32 bits, e.g. 120.255.123.0);
Advantages and Disadvantages of Advantages and Disadvantages of TCP/IPTCP/IP
AdvantagesAdvantages Suitable for WAN Direct Access to the Internet Supported by most of the
computer and operating system support routing support SNMP, DHCP
(dynamically assign client IP addresses),
support Internet Protocols like POP(Post Office Protocol), HTTP.
Centralized TCP/IP domain assignment to allow internetworking between organizations
IP address
DisadvantagesDisadvantages Difficult to administer global expansions of Internet has
limited the availability of unique domain numbers
difficult to set up high overhead slower than IPX and NetBEUI
DevicesDevicesDevices that allow expansion of network locally or
across the world and layer of the OSI model they operate.
RepeaterRepeater operate at Physical layer has no concern for the type of data being transmitted, packet
address and the protocol being used cannot perform filtering or translation of the data and does
not help to ease network congestion cannot connect different network architectures allows easy expansion of the network over larger distance
and connection between different media
BridgeBridge Operates at the Data Link Layer of the OSI model or
Media Access Control sublayer of the Data Link layer (has access to this address information)
can filter to ease network congestion can connect different media and network architectures slower than repeater
RouterRouter
Operate at the Network layer can connect different media and network architectures choose the best path for packet through an internetwork reduce network traffic by not forwarding broadcasts or
corrupt packets more expansive and complex than repeater and bridge only work with routable protocol (like TCP/IP, IPX/SPX,
AppleTalk and etc) dynamic routing updates create network traffic slower than bridge because need to perform more
calculation on the packet
BrouterBrouter
Combination of bridge and router good at hybrid network using mixture of routable and
nonroutable protocols routable packet -- function as router (choosing the best
path to forward packet) nonroutable packet --- function as bridge (forwarding
packet based on hardware address
GatewayGateway work at the Application layer of OSI model can translate information between two different
network architectures or data formats ( for example, allows network communication between a TCP/IP LAN and IBM mainframe system using SNA and also can convert Microsoft Mail to SMTP for transmission over Internet
hard to install and configure; slower and more expensive
SummarySummary
OSI reference model plays a vital role in networking. OSI
model. Networking can be broken into seven layers with
OSI model. Therefore, the complexity of networked
communications, from application to hardware is broken
into a series of interconnected tasks and activities. It
creates a method to solve big problem by deconstructing
them into a series of smaller problems, that can then be
solved individually.
References & Related WebsitesReferences & Related Websites Matthew Strebe, Charles Perkins and James Chellis.
“MCSE: NT Server 4 Study Guide” Second Edition. SYBEX Inc 1998.
Joe Casad. “MCSE: Windows NT Server & Workstation 4”. New Riders Publishing 1996.
TCP/IP Networking : Architecture, Administration and Programming,James Martin, Joe Leben / Prentice Hall / August 1994
MCSE:Networking Essentials (2nd Edition),James Chellis. Sybex / June 1998
http://www.cit.ac.nz/smac/winnt/pt1_9.htm#Start http://www.vcs-s.com/network_topology.htm http://dir.yahoo.com/Computers_and_Internet/Communicat
ions_and_Networking/ http://www.mcpmag.com/