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Chapter 6 Networking Protocols

Chapter 6 Networking Protocols. Introduction. Look at: Protocol Basics(6.1) A Brief Protocol Prospectus(6.2) Transmission Control Protocol/Internet Protocol (TCP/IP)(6.3) TCP/IP Network Access Layer Protocols(6.4). Introduction. Look at: TCP/IP Internet Layer Protocols(6.5)

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Chapter 6 Networking Protocols

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  1. Chapter 6 Networking Protocols

  2. Introduction • Look at: • Protocol Basics(6.1) • A Brief Protocol Prospectus(6.2) • Transmission Control Protocol/Internet Protocol (TCP/IP)(6.3) • TCP/IP Network Access Layer Protocols(6.4)

  3. Introduction • Look at: • TCP/IP Internet Layer Protocols(6.5) • TCP/IP Transport Layer Protocols(6.6) • TCP/IP Application Layer Protocols(6.7)

  4. Protocol Basics • A protocol is a set of rules and conventions that determines how computers exchange information over a network medium • A wide variety of communication protocols exist, and many of them rely on others for operation • Groups of related protocols are often called stacksorprotocol stacks

  5. A Brief Protocol Prospectus • Data packets can be sent over the medium using any one of a number of protocols • Protocols can be either standard or proprietary • A standard protocol is one where users can purchase equipment from any manufacturer because it is programmed to communicate universally

  6. A Brief Protocol Prospectus • A proprietary protocol is usually protected by patents or other legal stipulation • Proprietary protocols include • XNS • NetBIOS • IPX/SPX • AppleTalk • DECNet

  7. A Brief Protocol Prospectus • XNS stands for the Xerox Network Systems • This is a suite of protocols created by Xerox in the late 1970s and early 1980s for use in Ethernet networks • XNS is used in very few new networks today

  8. A Brief Protocol Prospectus • The Network Basic Input/Output System (NetBIOS) interface was developed in 1983 for IBM • The intention was to allow applications on different computers to communicate within a local area network • NetBIOS was not designed for large networks

  9. A Brief Protocol Prospectus • In the early 1980s, Novell introduced its own network protocol stack called Internetwork Packet Exchange/Sequenced Packet Exchange (IPX/SPX) • This stack was based on the XNS network protocol family • IPX is the Network layer protocol • SPX is the Transport layer protocol

  10. A Brief Protocol Prospectus • AppleTalk is Macintosh’s networking protocol • It is designed to be a flexible, simple, and inexpensive network means for connecting computers, peripherals, and servers • Newer versions of Macintosh operating systems use TCP/IP and SMB as default protocols rather than AppleTalk • AppleTalk is a protocol and LocalTalk is a media type

  11. A Brief Protocol Prospectus • DECnetis a proprietary network protocol designed by Digital Equipment Corporation • Currently two versions of DECnet are in use: • DECnet Phase IV which is based on the Phase IV Digital Network Architecture (DNA) • DECnet/OSI also called DECnet Phase V is a layered model

  12. Transmission Control Protocol/Internet Protocol • TCP/IP is considered the language of the Internet • It is the most widely used protocol today • It is a suite, or stack, of small, specialized protocols • Because of its routing ability, TCP/IP has become the protocol of choice for many LANs, as well as the basis for the Internet, making it the standard

  13. Transmission Control Protocol/Internet Protocol • In the early 1970s, the Department of Defense funded ARPA to design a new set of computer communication protocols that would allow multiple networks to be interconnected in a flexible and dynamic way • The protocol developed was originally called Network Control Protocol • This success led to the implementation of the two main Internet protocols • These are Transmission Control Protocol and Internet Protocol (TCP/IP)

  14. Transmission Control Protocol/Internet Protocol • TCP/IP’s implementation of the OSI model makes functionality simpler • It maps the same seven layers of the OSI model to a four-layer TCP/IP model instead • The TCP/IP model focuses more on delivering interconnectivity than on functional layers

  15. Transmission Control Protocol/Internet Protocol • Since TCP/IP is the language of the Internet, you may also hear this model referred to as the Internet reference model • The Layers are: • Network Access • Internet • Transport • Application

  16. TCP/IP Network Access Layer Protocols • The Network Access layer is the lowest layer in the model • It Maps to Layers 1 (Physical) and 2 (Data Link) of the OSI model • It is responsible for the delivery of datagrams by creating a frame for the network type and then sending the data to the wire

  17. TCP/IP Network Access Layer Protocols • This layer contains the protocols that are used to deliver data to computers and devices on the network • These include Serial Line Interface Protocol (SLIP) and Point-to-Point Protocol (PPP) • These are communication protocols for serial data transmission by which IP packets can be sent over a modem

  18. TCP/IP Network Access Layer Protocols • Other protocols that are used at this layer include a means to relate different types of addresses to each other: • the Address Resolution Protocol (ARP) • the Reverse Address Resolution Protocol (RARP) • This layer defines the logical network layout so routers can determine where to forward packets

  19. TCP/IP Internet Layer Protocols • The layer above the Network Access layer is called the Internet layer • It manages the routing of packets that are to be forwarded on to different networks • It relies on routable protocols for delivery

  20. TCP/IP Internet Layer Protocols • The Internet Protocol (IP) is responsible for making data packets routable • It is a forwarding protocol that uses routing tables that are created by routing protocols • It is a simple, connectionless internetworking protocol • The basis of IP is how it uses routing tables to make decisions about routing an IP packet

  21. TCP/IP Internet Layer Protocols • Every host on the network needs an IP address • TCP/IP uses a 32-bit Layer 3 address in the format xxx.xxx.xxx.xxx to identify the network and the host compute • Each set of xxx is called an octet

  22. TCP/IP Internet Layer Protocols • There are five classes of IP addresses their corresponding numbers are: • Class A: Has a first octet number between 1 and 126 and can support a network with 16,777,216 hosts. • Class B: Has a first octet number between 128 and 191 and can support 65,536 hosts

  23. TCP/IP Internet Layer Protocols • There are five classes of IP addresses their corresponding numbers are: • Class C: Has a first octet number between 192 and 223 and can support 254 hosts per network • Class D: Begins at 224 and ends at 239. This address class is reserved for sending multicast messages

  24. TCP/IP Internet Layer Protocols • A There are five classes of IP addresses their corresponding numbers are: • Class E: Begins with 240 and ends at 255. This address class is reserved for experimental use • The IP address 127.0.0.1 is used as the loopback address

  25. TCP/IP Internet Layer Protocols • A datagramis the packet format defined by IP • Datagrams are packets that consist of a header, data, and a trailer • The header contains information that the network needs to route the datagram • Trailers typically contain a checksum value, which is used to ensure that the data is not modified in transit

  26. TCP/IP Internet Layer Protocols • IP delivers the datagram by checking the destination address in the header • When IP checks the destination address in the header, if it is the address of a host on the local network, the datagram is delivered directly to the destination • If it is not on the local network, the datagram is passed on for delivery

  27. TCP/IP Internet Layer Protocols • Each router that a datagram passes through is considered a hop • A system transmits IP datagrams as fast as it can generate them • IP has two features that can affect throughput • the IP Time to Live (TTL) • IP Fragmentation

  28. TCP/IP Internet Layer Protocols • By interconnecting multiple switches with redundant paths, you overcome problems with faulty cables or port failures • Another less well-known side effect of a loop is the corruption of the forwarding tables on all the switches • It would take very little time before Layer 2 broadcast loops completely destroy the functionality of a network

  29. TCP/IP Internet Layer Protocols • The Spanning Tree Protocol (STP) prevents bridging loops by identifying a preferred path through a series of looped bridges • Administrators can provide redundancy and fault-tolerance by wiring a loop, and then using STP turn off ports that would cause loops to occur • If a primary link fails, STP will reactivate the back-up port allowing normal operation of the network to continue

  30. TCP/IP Internet Layer Protocols • The TTL field is actually the number of hops the datagram has made • IP places a limit on how long a datagram may live in the network • Specifications for higher-layer protocols usually assume that the maximum time a datagram can live in the network is only two minutes

  31. TCP/IP Internet Layer Protocols • Each type of network has a maximum transmission unit (MTU), which is the largest packet it can transfer • A datagram received from one network may be too large to be transmitted in a single packet on another network • It may be necessary to divide the datagram into smaller pieces • This division process is called fragmentation

  32. TCP/IP Internet Layer Protocols • Internet Control Message Protocol (ICMP) is part of the Internet layer and uses IP datagram delivery to send its messages • ICMP uses the basic support of IP as if it was higher-level protocol, but it is actually an integrated part of IP • ICMP is a protocol meant to be used as an aid for other protocols • It is used to test for connectivity and search for configuration errors in a network

  33. TCP/IP Internet Layer Protocols • PING uses the ICMP echo function • A small packet containing an ICMPecho message is sent through the network to a particular IP address • The computer that sent the packet then waits for a return packet • If the connections are good and the target computer is up, the echo message return packet will be received

  34. TCP/IP Internet Layer Protocols • PING is one of the most useful network tools available because it tests the most basic function of an IP network • Traceroutewas originally developed for the Unix operating system but is used for many operating systems and most routers • It is used to track the path a packet takes to get to its destination • It measures how long it takes to travel through each hop to get to its target

  35. TCP/IP Internet Layer Protocols • Traceroute uses an ICMP echo request packet to find the path • Besides assisting in troubleshooting functions such as PING and Traceroute, ICMP capabilities include: • Announcing network errors • Congestion • Timeout notification

  36. TCP/IP Transport Layer Protocols • The protocol layer above the Internet layer is the Transportlayer • It is responsible for providing end-to-end data integrity • It also provides a reliable communication service so that an extended two-way conversation may take place

  37. TCP/IP Transport Layer Protocols • This layer accepts and returns information to be transmitted as a stream of characters • It uses open and close commands to initiate and terminate the connection • It consists of two protocols: • Transmission Control Protocol (TCP) • User Datagram Protocol (UDP)

  38. TCP/IP Transport Layer Protocols • TCP provides connection-oriented data transmission • It can support multiple data streams • It provides for flow and error control • It uses sequence numbers and acknowledgements to guarantee delivery

  39. TCP/IP Transport Layer Protocols • Sockets make up a TCP connection • The two most typical network applications that use TCP are: • File Transfer Protocol (FTP) • Telnet • Telnet uses port 23 • FTP uses port 21

  40. TCP/IP Transport Layer Protocols • UDP does not provide either sequencing or acknowledgements • It is a connectionless protocol • It is used a lot in telephony traffic and the Remote Procedure Call (RPC) • The major difference between TCP and UDP is reliability

  41. TCP/IP Application Layer Protocols • The top layer in the Internet reference model is the Application layer • This is how applications and certain services access the network • It provides the services that applications use to communicate over the network • It serves as a service provider for workstations and applications.

  42. TCP/IP Application Layer Protocols • The most widely known and implemented TCP/IP Application layer services are: • File Transfer Protocol (FTP) which allows files to be uploaded and downloaded on port 21 • Telnet which uses terminal emulation for access to remote hosts using port 23

  43. TCP/IP Application Layer Protocols • The most widely known and implemented TCP/IP Application layer services are: • Simple Mail Transfer Protocol (SMTP) which supports basic message delivery services between mail servers on port 25 • HyperText Transfer Protocol (HTTP) which is a low-overhead Web browser service protocol that uses port 80

  44. TCP/IP Application Layer Protocols • The most widely known and implemented TCP/IP Application layer services are: • Simple Network Management Protocol (SNMP) which uses UDP port 161 to collect information from network devices. • Network News Transfer Protocol (NNTP): handles distribution and posting of news articles using port 119

  45. TCP/IP Application Layer Protocols • The most widely known and implemented TCP/IP Application layer services are: • Dynamic Host Configuration Protocol (DHCP) allows for automatic IP addressing • Domain Name Service (DNS) uses UDP port 53 for resolving domain names to IP addresses

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