Ministry of Communications and Information Technology Information Technology Institute Network Fundamentals Introduction to Internet Lec2

What is the Internet?  Internet Origin and History  Who Owns the Internet?  Internet Connections

Internet development in Egypt:  historical background  1993 via a 9.6K link between the Egyptian Universities Network and France  1994 the Egyptian domain was divided into three major subdomains  sci.eg  com.eg  gov.eg  Provide 64K digital access to France

Internet Gateway in Egypt

Who owns the Internet?  No one actually owns the Internet  Many Orgs, ISPs, Companies, Govs own pieces of Internet Infrastructure.  But many organization oversee.  ISOC Internet Society  IETF Internet Engineering Task Force

Network Communicating Protocols

The Need for Protocols  Protocols are needed for computer networks to communicate efficiently  Network protocols are set of rules that enable data to flow from one NIC to another  Protocols control the messages origination, the messages end, and the messages quantity in the network.

Major Networking Protocols  NetBEUI  IPX/SPX  TCP/IP  AppleTalk

NetBIOS  Network Basic Input/Output System.  A common network protocol that allows applications on different computers to communicate within a local area network (LAN).  It was created by IBM for its early PC Network, and was adopted by Microsoft.  It does not support a routing mechanism.  NetBIOS was later formalized in NetBEUI.

NetBEUI  NetBIOS Extended User Interface.  This is an enhanced version of the NetBIOS protocol used by network operating systems (NOS), such as Microsoft's Windows NT.  NetBEUI was developed by IBM for its LAN Manager product and has been adopted by Microsoft for its Windows NT, LAN Manager, and Windows for Workgroups products.  Non-routable

NetBEUI Advantages and Disadvantages  Advantages  High speed on small networks  ease of implementation  small memory overhead  Self tuned (does not need configuration)  Disadvantages  It cannot be routed between networks.

IPX/SPX  Internet Packet Exchange Sequenced Packet Exchange.  A communications protocol devised by Novell for Novell NetWare.  IPX/SPX packets can be routed from one network to another

IPX/SPX Advantages and Disadvantages  Advantages  Ease of setup.  Support for routing between networks.  Speeds greater than TCP/IP for NT.  Disadvantages  Slower than NetBEUI.  IPX/SPX is not a vendor neutral

TCP/IP  Transmission Control Protocol/Internet Protocol.  TCP/IP is open standard protocol  Not tied to one vendor  TCP/IP is the internet protocol  Now internet use TCP/IP v4  Next version TCP/IP v6  It is the default protocol for  Windows NT4  Windows 2000  UNIX

TCP/IP Advantages and Disadvantages  Advantages  Broad connectivity among all types of computers and servers  Direct access to the Internet  Disadvantages  Difficulty of setup  Slower than IPX & NetBEUI

AppleTalk  AppleTalk is a set of local area network communication protocols originally created for Apple computers. An AppleTalk network can support up to 32 devices and data can be exchanged at a speed of kilobits per second (Kbps).

OSI Reference Model  OSI: Open Systems Interconnection  The OSI model is the primary architectural model for networks.  It describes how data and network information are communicated from an application on one computer, through the network media, to an application on another computer.  The model was defined by the International Organization for Standardization (ISO)  The OSI reference model breaks this approach into layers.

Advantages of Reference Models  It divides the network communication process into smaller and simpler components, thus aiding component development, design, and troubleshooting.  It allows multiple-vendor development through standardization of network components.  It encourages industry standardization by defining what functions occur at each layer of the model.  It allows various types of network hardware and software to communicate.  It prevents changes in one layer from affecting other layers, so it does not hamper development.

OSI Seven Layers  Application  Presentation  Session  Transport  Network  Data Link  Physical

What should I send?  End-user Interface  Where client applications reside  Displays received information  Sends user’s data to lower layers Application Layer

Presentation Layer  The presentation layer is responsible for the delivery and formatting of information to the application layer for further processing or display.  It relieves the application layer of concern regarding syntactical differences in data representation within the end-user systems.  An example of a presentation service would be the conversion of an EBCDIC-coded text file to an ASCII- coded file.

Close Connection You are welcome! Thank you. I would like to send you something. Sounds good! Establish Connection Controls the sessions between the local and remote applications Session Layer

Transport Layer  There is services that can be optionally provided at this layer:  Connection-Oriented  Same Order Delivery  The simplest way of doing this is to give each packet a number, and allow the receiver to reorder the packets.  Reliable Data  Flow Control  Without flow control a computer might be flooded with so much information that it can't hold it all before dealing with it.

Network Layer  Organize data into datagrams (packets)  Addresses messages  Routing  Provides the functional and procedural means of transferring variable length data sequences from a source to a destination via one or more networks

Data Link Layer  Reliable data transfer across a physical link  It provides the means to detect errors that may occur in the Physical layer.  Organize the data into frames, to be put on the physical medium  Transfers data between adjacent network nodes  The data link layer is split into MAC and LLC sublayers

Physical Layer  The Physical layer defines all the electrical and physical specifications for devices.  The physical layer is the most basic network layer, providing only the means of transmitting raw bits.

The Internet Protocol TCP/IP Protocol Suite

 Specified and extensively used before the OSI model  Developed by research funded US Department of Defense  Used by the Internet

TCP/IP Protocol Suite

Addressing

Layers and Addresses in TCP/IP

Physical addresses

IP addresses

Port addresses

Where do I go? Provides physical routing information Network Layer Addressing

IP Address 255 Dotted Decimal Maximum NetworkHost 32 Bits

IP Addressing 255 Dotted Decimal Maximum NetworkHost Binary 32 Bits

Decimal Equivalents of Bit Patterns = = = = = = = = =

IP Address Classes  Class A:  Class B:  Class C:  Class D: Multicast  Class E: Research Network Host Network Host Network Host 8 Bits

IP Address Classes 1 Class A: Bits: 0NNNNNNN Host Range (1-126) 1 Class B: Bits: 10NNNNNN Network Host Range ( ) 1 Class C: Bits: 110NNNNN Network Host Range ( ) 1 Class D: Bits: 1110MMMM Multicast Group Range ( ) Network Multicast Group

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