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Network Protocols

Network Protocols. A protocol is a set of rules that governs the communications between computers on a network.

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Network Protocols

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  1. Network Protocols A protocol is a set of rules that governs the communications between computers on a network. Many different types of network protocols and standards are required to ensure that your computer can communicate with another computer located on the next desk or half-way around the world. Networking Protocols are split into different layers. The OSI Reference Model defines seven layers of networking protocols.

  2. OSI Overview • Application Layer: End user processes like file transfer, e-mail, network software services. E.g. Telnet, FTP • Presentation/Syntax Layer: Format, Encrypt data to send across network. • Session Layer: Establishes, manages and terminates connections between applications. • Transport Layer: End-to-end error recovery, flow control. •  Network Layer: Switching, Routing, Addressing, internetworking, error handling, congestion control and packet sequencing. • Data Link Layer: Encoding, decoding data packets into bits. • Physical Layer: Conveys the bit stream (electrical, light, radio) E.g. Ethernet, RS232, ATM

  3. Physical/Data Link Layers • The physical layer of the network focuses on hardware issues. • The most common protocol used at the physical layer is Ethernet Ethernet – • The original Ethernet standard was developed in 1983 • Max speed of 10 Mbps (phenomonal at the time!). Fast Ethernet – • The Fast Ethernet protocol supports transmission up to 100 Mbps. • Fast Ethernet requires the use of different, more expensive network concentrators/hubs and network interface cards. Gigabit Ethernet – • Gigabit Ethernet standard is a protocol that has a transmission speed of 1 Gbps (1000 Mbps). • It can be used with both fiber optic cabling and copper.

  4. Ethernet Protocol Summary

  5. OutdatedPhysical/Data Link Layers LocalTalk – • Developed by Apple Computer • LocalTalk adapters and special twisted pair cable can be used to connect a series of older computers through the serial port • Its speed of transmission is only 230 Kbps. Token Ring • The Token Ring protocol was developed by IBM in the mid-1980s • In Token Ring, the computers are connected so that the signal travels around the network from one computer to another in a logical ring. • If a computer does not have information to transmit, it simply passes the token on. • It can operate at transmission speeds of 4 Mbps or 16 Mbps.

  6. IP and IPX (Network Layer) • The network layer is in charge of routing network messages (data) from one computer to another. The common protocols at this layer are IP and IPX • Networks using the IP and IPX protocols assign logical addresses (which are made up of the MAC address and the network address) to the devices on the network • The network layer takes care of assigning the correct addresses (via IP or IPX) and then uses routers to send the data packets to other networks.

  7. TCP and SPX (Transport Layer) • Handles transportation of the data packets from one network to another. • Data broken into small data packets, each with header information that identifies its correct sequence and document. • When the data packets are sent over a network, they may or may not take the same route -- it doesn't matter. • At the receiving end, the data packets are re-assembled into the proper order. • After all packets are received, a message goes back to the originating network. • If a packet does not arrive, a message to "re-send" is sent back to the originating network. • TCP, paired with IP, is by far the most popular protocol at the transport level.

  8. NETBEUI • Network Basic Input Output System (NetBIOS) was developed by IBM and adopted by Microsoft as the foundation for its networking. Microsoft updated it and called it NetBIOS Enhanced User Interface (NetBEUI). • NetBEUI is a fast and efficient protocol with very good error correction. • It needs little setting up and configuration. • Can only handle 254 connections and has poor security. • It can only be used in small networks and requires the use of other protocols in larger networks. It is commonly used in conjunction with TCP/IP. • NetBEUI Addressing: NetBEUI has no addressing as such, but it has to be able to distinguish between workstations on a network. It does this by

  9. IPX/SPX • Internetwork Packet Exchange/Sequenced Packet Exchange (IPX/SPX) was developed by Xerox and adopted by Novell as the basic of the Netware network operating system. • Later versions of Netware have been changed to use TCP/IP • IPX/SPX Addressing: Like TCP/IP, each address in an IPX/SPX network must be unique. • This is achieved by using the hard-coded address that is programmed (MAC Address) onto each network interface card (NIC) during manufacture. • The system administrator assigns the network an eight bit hexadecimal network address. • A complete IPX address is the combination of the external number and the devices MAC address.

  10. TCP/IP • Every machine on a TCP/IP network must have a unique address. • If IP Addresses are manually assigned, there is a chance of duplication of an IP Address on the network. • It is easier to have IP Addresses assigned automatically using the Dynamic Host Configuration Protocol (DHCP). • Each IP Address is a unique 32 bit number that is divided into groups of four digits called octets.

  11. Session/Presentation/Application Layers • DNS - Domain Name System - translates network address (such as IP addresses) into terms understood by humans (such as URLs) • DHCP - Dynamic Host Configuration Protocol - can automatically assign Internet addresses to computers and users • FTP - File Transfer Protocol - a protocol that is used to transfer and manipulate files on the Internet • HTTP - HyperText Transfer Protocol - An Internet-based protocol for sending and receiving webpages • IMAP - Internet Message Access Protocol - A protocol for e-mail messages on the Internet • IRC - Internet Relay Chat - a protocol used for Internet chat and other communications • POP3 - Post Office protocol Version 3 - a protocol used by e-mail clients to retrieve messages from remote servers • SMTP - Simple Mail Transfer Protocol - A protocol for e-mail messages on the Internet

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