Chapter Three

1. Chapter Three Network Protocols

2. Introduction to Protocols • Protocol • Rules network uses to transfer data • Protocols that can span more than one LAN segment are routable • SNA & DLC becoming outdated due to non-routability • Multiprotocol network • Network using more than one protocol

3. TCP/IP • Transmission Control Protocol/Internet Protocol (TCP/IP) • Suite of small, specialized protocols called subprotocols OSI Model TCP/IP Figure 3-1: TCP/IP compared to the OSI Model

4. The TCP/IP Core Protocols • Certain subprotocols of TCP/IP suite • Operate in Transport or Network layers of OSI Model • Provide basic services to protocols in other layers of TCP/IP • TCP and IP are most significant core protocols in TCP/IP suite

5. Internet Protocol (IP) • Provides information about how and where data should be delivered • Subprotocol that enables TCP/IP to internetwork • To internetwork is to traverse more than one LAN segment and more than one type of network through a router • In an internetwork, the individual networks that are joined together are called subnetworks (or subnets)

6. Internet Protocol (IP) • IP datagram • IP portion of TCP/IP frame that acts as an envelope for data • Contains information necessary for routers to transfer data between subnets Figure 3-2: Components of an IP datagram

7. Internet Protocol (IP) • Version • IPv4 – current version used for 20 years • IPv6 – in process • Time to live (TTL) – max time, in seconds, that a datagram can remain on the network before it is discarded • Also corresponds to # of router hops

8. Internet Protocol (IP) • IP is an unreliable, connectionless protocol, which means it does not guarantee delivery of data • Connectionless • Allows protocol to service a request without requesting verified session and without guaranteeing delivery of data

9. Transport Control Protocol (TCP) • TCP • Provides reliable data delivery services • Connection-oriented subprotocol • Requires establishment of connection between communicating nodes before protocol will transmit data • TCP segment • Holds TCP data fields • Becomes encapsulated by IP datagram

10. Transport Control Protocol (TCP) • Port • Address on host where application makes itself available to incoming data Figure 3-3: A TCP segment

11. Additional Core Protocols of the TCP/IP Suite • User Datagram Protocol (UDP) • Connectionless transport service • Lack of sophistication makes it more efficient than TCP • Live audio/video transmissions over the Internet • Internet Control Message Protocol (ICMP) • Notifies sender of an error in transmission process and that packets were not delivered • Sits between IP & TCP in Internet layer of TCP/IP model • Used by PING diagnostic tool • Address Resolution Protocol (ARP) • Obtains MAC address of host or node • Creates local database mapping MAC address to host’s IP address

12. TCP/IP Application Layer Protocols • These protocols work over TCP (or UDP) and IP: • Telnet • Used to log on to remote hosts using TCP/IP protocol suite • File Transfer Protocol (FTP) • Used to send and receive files via TCP/IP • Simple Mail Transfer Protocol (SMTP) • Responsible for moving messages from one e-mail server to another, using the Internet and other TCP/IP-based networks • Simple Network Management Protocol (SNMP) • Manages devices on a TCP/IP network

13. Addressing in TCP/IP • IP Address • Logical address used in TCP/IP networking • Unique 32-bit number • Divided into four groups of octets (8-bit bytes) that are separated by periods • IP addresses are assigned and used according to very specific parameters • Example: 144.92.43.178

14. Addressing in TCP/IP • Though 8 bits have 256 possible combinations, only the numbers 1 through 254 are used to identify networks and hosts • Numbers 0 and 255 are reserved for broadcasts • Broadcast are transmissions to all stations on a network Table 3-1: Commonly used TCP/IP classes

15. Addressing in TCP/IP • Group A • Only 126 available – used/reserved for large corporations or governments • Share the first octet (1-126) • i.e. 23.78.110.109, 23.164.32.97 • Group B • Share the first two octets (128-191) • i.e. 168.34.88.29, 168.34.55.41 • Group C • Share the first three octets (192-223) • i.e 204.139.118.7, 204.139.118.14

16. Addressing in TCP/IP • Loopback address • IP address reserved for communicating from a node to itself • Value of the loopback address is always 127.0.0.1 (try it) • Internet Corporation for Assigned Names and Numbers (ICANN) – formerly InterNIC • Non-profit organization currently designated by U.S. government to maintain and assign IP addresses

17. Addressing in TCP/IP • Firewall • Specialized device (typically a router) • Selectively filters or blocks traffic between networks • May be strictly hardware-based or may involve a combination of hardware and software • Host • Computer connected to a network using the TCP/IP protocol

18. Addressing in TCP/IP • IP address data are sent across the network in binary form • In IP address 131.127.3.22, to convert the first octet (131) to a binary number: • On Windows 2000, click Start, point to Programs, point to Accessories, then click Calculator • Click View, then click Scientific (make sure Dec option button is selected) • Type 131, then click Bin option button • The binary equivalent of number 131, 10000011, appears in the display window

19. Addressing in TCP/IP • Static IP address • IP address manually assigned to a device • Dynamic Host Configuration Protocol (DHCP) • Application layer protocol • Manages dynamic distribution of IP addresses on a network

20. Viewing Current IP Information Figure 3-4: Example of an IP configuration window

21. Viewing Current IP Information Figure 3-5: IP address information on a Windows 2000 workstation

22. Addresses and Names • In addition to using IP addresses, TCP/IP networks use names for networks and hosts • Each host requires a host name • Each network requires a network name, also called a domain name • Together, host name and domain name constitute the fully qualified domain name (FQDN)

23. IPX/SPX • Internetwork Packet Exchange/Sequenced Packet Exchange (IPX/SPX) • Protocol originally developed by Xerox • Modified and adopted by Novell in the 1980s for the NetWare network operating system Figure 3-6: IPX/SPX compared to the OSI Model

24. IPX/SPX Core Protocols • Internetwork Packet Exchange (IPX) • Operates at Network layer of OSI Model • Provides routing and internetworking services • Similar to IP in TCP/IP suite • Socket – logical address assigned to a specific process Figure 3-7: Components of an IPX datagram

25. IPX/SPX Core Protocols • Sequenced Packet Exchange (SPX) • Belongs to Transport layer of OSI Model • Works in tandem with IPX to ensure data are received: • Whole • In sequence • Error free • Similar to TCP

26. IPX/SPX Core Protocols Figure 3-8: SPX packet encapsulated by an IPX datagram

27. IPX/SPX Core Protocols • Service Advertising Protocol (SAP) • Works in Application, Presentation, Session, and Transport layers of OSI Model • Runs directly over IPX • Used by NetWare servers and routersto advertise to entire network which services they can provide • Can lead to unnecessary network traffic

28. IPX/SPX Core Protocols • NetWare Core Protocol (NCP) • Works within Presentation and Sessions layers of OSI Model • Works over IPX • Handles requests for services between clients and servers

29. Addressing in IPX/SPX • IPX address • Address assigned to a device on an IPX/SPX network • Contains two parts: • Network address (external network number) • Established Network Admin when network is installed • Node address • NIC MAC address • Example (8.12): • 000008A2:0060973E97F3

30. NetBIOS and NetBEUI • Network Basic Input Output System (NetBIOS) • Originally designed by IBM to provide Transport and Session layer services • Adopted by Microsoft as its foundation protocol • Microsoft added Application layer component called NetBEUI

31. NetBIOS and NetBEUI • NetBIOS Enhanced User Interface • Fast and efficient protocol • Consumes few network resources • Provides excellent error correction • Requires little configuration • Can handle only 254 connections • Does not allow for good security • By itself, it is not routable

32. NetBIOS and NetBEUI Compared to the OSI Model Figure 3-9: NetBIOS/NetBEUI compared to the OSI Model

33. NetBIOS Addressing Figure 3-10: Identification tab in Network properties

34. AppleTalk • Protocol suite used to interconnect Macintosh computers • Originally designed to support peer-to-peer networking among Macintoshes • Can now be routed between network segments and integrated with NetWare- and Microsoft-based networks • AppleTalk networks are separated into logical groups of computers called AppleTalk zones • Apple has begun supporting TCP/IP

35. AppleTalk and OSI Model Figure 3-11: AppleTalk protocol compared to OSI Model

36. Addressing in AppleTalk • AppleTalk node ID • Unique 8-bit or 16-bit number identifying a computer on an AppleTalk network • AppleTalk network number • Unique 16-bit number identifying the network to which a node is connected

37. Installing Protocols • After installing protocols, they must be binded to NICs and services they run on or with • Binding • Process of assigning one network component to work with another