1. Chapter 4: Network Protocols
Network+ Guide to Networks
Third Edition
Chapter 4: Network Protocols

2. Objectives
Identify the characteristics of TCP/IP, IPX/SPX, NetBIOS, and AppleTalk
Understand how key network protocols correlate to layers of the OSI Model
Identify the core protocols of the TCP/IP suite and describe their functions
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3. Objectives (continued)
Understand the most popular protocol addressing schemes
Describe the purpose and implementation of the domain name system
Install protocols on Windows XP clients
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4. Introduction To Protocols
Protocol is a rule that governs how networks communicate
Define the standards for communication between network devices
Vary according to their speed, transmission efficiency, utilization of resources, ease of setup, compatibility, and ability to travel between different LANs
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5. Introduction To Protocols
Networks running more than one protocol are called multiprotocol networks
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6. Transmission Control Protocol /Internet Protocol (TCP/IP)
TCP/IP is not simply one protocol, but rather a suite of specialized protocols—including TCP, IP, UDP, ARP, and many others—called sub protocols
Extremely popular because of low cost
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7. TCP/IP (continued)
Has ability to communicate between a multitude of dissimilar platforms
The core protocols are free and their code is available for anyone to read or modify
Its routable, because they carry Network layer addressing information that can be interpreted by a router
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8. TCP/IP (continued) TCP/IP Compared to the OSI Model
Has flexibility because it can run on virtually any combination of network operating systems or network media
TCP/IP Compared to the OSI Model
The TCP/IP suite of protocols can be divided into four layers that roughly correspond to the seven layers of the OSI Model
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9. TCP/IP (continued) TCP/IP Compared to the OSI Model (continued)
Application layer
Applications gain access to the network through this layer, via protocols
Transport layer
Holds the Transmission Control Protocol (TCP) and User Datagram Protocol (UDP), which provide flow control, error checking, and sequencing
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10. TCP/IP (continued) TCP/IP Compared to the OSI Model (continued)
Internet layer
Holds the Internet Protocol (IP), Internet Control Message Protocol (ICMP), and Address Resolution Protocol (ARP).These protocols handle message routing, error reporting, delivery confirmation, and logical addressing
Network Interface Layer
This layer handles the formatting of data and transmission to the network wire
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11. TCP/IP (continued) The TCP/IP Core Protocols
Certain sub protocols of the TCP/IP suite
Operate in the Transport or Network layers of the OSI Model
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12. TCP/IP (continued) Transmission Control Protocol (TCP)
Operates in the Transport layer of both the OSI and the TCP/IP Models and provides reliable data delivery services
TCP is a connection-oriented sub protocol
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13. TCP/IP (continued)
Fields belonging to a TCP segment are described in the following list:
Source port
Destination port
Sequence number
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14. TCP/IP (continued) Acknowledgment number (ACK) TCP header length
Reserved
Flags
Sliding-window size (or window)
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15. TCP/IP (continued)
Checksum - Allows the receiving node to determine whether the TCP segment became corrupted during transmission
Urgent pointer - Indicate a location in the data field
Options - Used to specify special options
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16. TCP/IP (continued)
Padding - Contains filler information to ensure that the size of the TCP header is a multiple of 32 bits
Data - Contains data originally sent by the source node and the size of the Data field depends on how much data needs to be transmitted
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17. TCP/IP (continued) User Datagram Protocol (UDP)
A connectionless transport service
UDP offers no assurance that packets will be received in the correct sequence
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18. TCP/IP (continued) User Datagram Protocol (UDP)
Provides no error checking or sequencing
More efficient for carrying messages that fit within one data packet
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19. TCP/IP (continued) Internet Protocol (IP)
Provides information about how and where data should be delivered, including the data’s source and destination addresses
IP is the sub protocol that enables TCP/IP to internetwork
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20. TCP/IP (continued) Internet Protocol (IP)
IP datagram acts as an envelope for data and contains information necessary for routers to transfer data between different LAN segments
IP is an unreliable, connectionless protocol, which means that it does not guarantee delivery of data
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21. TCP/IP (continued) Internet Control Message Protocol (ICMP)
An Internet layer protocol that reports on the success or failure of data delivery
ICMP announcements provide critical information for troubleshooting network problems
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22. TCP/IP (continued) Address Resolution Protocol (ARP)
An Internet layer protocol that obtains the MAC (physical) address of a host, or node, then creates a database that maps the MAC address to the host’s IP (logical) address
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23. TCP/IP (continued) Address Resolution Protocol (ARP) table
Dynamic ARP table entries are created when a client makes an ARP request that cannot be satisfied by data already in the ARP table
Static ARP table entries are those that someone has entered manually using the ARP utility
ARP can be a valuable troubleshooting tool
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24. TCP/IP (continued) Reverse Address Resolution Protocol (RARP)
Allow the client to send a broadcast message with its MAC address and receive an IP address in reply
RARP was originally developed as a means for diskless workstations
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25. TCP/IP (continued) Addressing in TCP/IP
Two kinds of addresses: Logical or physical
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26. TCP/IP (continued)
Logical (or Network layer) can be manually or automatically assigned and must follow rules set by the protocol standards
Physical (or MAC, or hardware) addresses are assigned to a device’s network interface card at the factory by its manufacturer
Addresses on TCP/IP-based networks are often called IP addresses
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27. TCP/IP (continued)
IP addresses are assigned and used according to very specific parameters
Each IP address is a unique 32-bit number, divided into four octets, or sets of 8-bits, that are separated by periods
An IP address contains two types of information: network and host
From the first octet you can determine the network class
Three types of network classes are used on modern LANs: Class A, Class B, and Class C
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28. TCP/IP (continued) IP Addresses specific parameters continued
Class D and Class E addresses do exist, but are rarely used
Class D addresses are reserved for a special type of transmission called multicasting
Multicasting allows one device to send data to a specific group of devices
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29. TCP/IP (continued) IP Addresses specific parameters continued
Some IP addresses are reserved for special functions, like broadcasts, and cannot be assigned to machines or devices
127 is not a valid first octet for any IP address
The range of addresses beginning with 127 is reserved for a device communicating with itself, or performing loopback communication
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30. TCP/IP (continued)
The command used to view IP information on a Windows XP workstation is ipconfig
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31. TCP/IP (continued) Binary and Dotted Decimal Notation
A decimal number between 1 and 255 represents each binary octet (for a total of 256 possibilities)
The binary system is the way that computers interpret IP addresses
In this system every piece of information is represented by 1s and 0s and each 1 or 0 constitutes a bit
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32. TCP/IP (continued) Subnet Mask
A special 32-bit number that, when combined with a device’s IP address, informs the rest of the network about the segment or network to which the device is attached
A more common term for subnet mask is net mask, and sometimes simply mask
Subnetting is a process of subdividing a single class of network into multiple, smaller logical networks, or segments
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33. TCP/IP (continued) Assigning IP Addresses
Every node on a network must have a unique IP address
If you add a node to a network and its IP address is already in use by another node on the same subnet, an error message will be generated on the new client
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34. TCP/IP (continued)
A manually assigned IP address is called a static IP address
Most network administrators rely on a network service to automatically assign them
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35. TCP/IP (continued)
Two methods of automatic IP addressing: BOOTP and DHCP
Bootstrap Protocol (BOOTP), an Application layer protocol, uses a central list of IP addresses and their associated devices’ MAC addresses to assign IP addresses to clients dynamically
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36. TCP/IP (continued)
An IP address that is assigned to a device upon request and is changeable is known as a dynamic IP address
BOOTP has the potential to issue additional information, such as the client’s subnet mask and requires administrators to enter every IP and MAC address manually into the BOOTP table
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37. TCP/IP (continued) Dynamic Host Configuration Protocol (DHCP)
An automated means of assigning a unique IP address to every device on a network
DHCP does not require a table of IP and MAC addresses on the server
DHCP does require configuration of DHCP service on a DHCP server
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38. TCP/IP (continued) Terminating a DHCP Lease Sockets and Ports
A DHCP lease may expire based on the period established for it in the server configuration or it may be manually terminated
Sockets and Ports
Every process on a machine is assigned a port number and the process’s port number plus its host machine’s IP address equals the process’s socket
The use of port numbers simplifies TCP/IP communications and ensures that data are transmitted to the correct application
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39. TCP/IP (continued)
Port numbers range from 0 to 65,539 and are divided by IANA into three types: Well Known Ports, Registered Ports, and Dynamic and/or Private Ports
Well Known Ports are in the range of 0 to 1023 and are assigned to processes that only the operating system or an Administrator of the system can access
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40. TCP/IP (continued)
Registered Ports are in the range of 1024 to These ports are accessible to network users and processes that do not have special administrative privileges
Dynamic and/or Private Ports are those from through and are open for use without restriction
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41. TCP/IP (continued) Addressing in IPv6
Known as IP next generation, or Ipng is slated to replace the current IP protocol, IPv4
IPv6 offers several advantages over IPv4, including a more efficient header, better security, better prioritization allowances, and automatic IP address configuration
The most valuable advantage IPv6 offers is its promise of billions and billions of additional IP addresses through its new addressing scheme
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42. TCP/IP (continued) Addressing in IPv6 (continued)
The most notable difference between IP addresses in IPv4 and IPv6 is their size
IPv4 addresses are composed of 32 bits, IPv6 are eight 16-bit fields and total 128 bits
IPv4 address contains binary numbers separated by a period, each field in an IPv6 address contains hexadecimal numbers separated by a colon
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43. TCP/IP (continued)
Host Names and Domain Name System (DNS) every device on the Internet is technically known as a host and every host can take a host name
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44. TCP/IP (continued)
Domain Names every host is a member of a domain, or a group of computers that belong to the same organization and have part of their IP addresses in common
A domain name is associated with a company or other type of organization
Local host name plus its domain name is a fully qualified host name
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45. TCP/IP (continued)
A domain name is represented by a series of character strings, called labels, separated by dots
Each label represents a level in the domain naming hierarchy
In the domain name, “com” is the top-level domain (TLD), “novell” is the second-level domain, and “www” is the third-level domain
Domain names must be registered with an Internet naming authority that works on behalf of ICANN
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46. TCP/IP (continued) Domain Name System (DNS)
A hierarchical way of associating domain names with IP addresses
“DNS” refers to both the Application-layer service and the organized system of computers and databases
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47. TCP/IP (continued)
The DNS service does not rely on one file or even one server, but rather on many computers across the globe
These computers are related in a hierarchical manner, with thirteen computers, known as root servers, acting as the ultimate authorities
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48. TCP/IP (continued)
DNS service is divided into three components: resolvers, name servers, and name space
Resolvers are any hosts on the Internet that need to look up domain name information
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49. TCP/IP (continued)
Name servers (or DNS servers) are servers that contain databases of associated names and IP addresses and provide this information to resolvers on request
The term name space refers to the database of Internet IP addresses and their associated names
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50. TCP/IP (continued)
Resource record is a single record that describes one piece of information in the DNS database
An address resource record is a type of resource record that maps the IP address of an Internet-connected device to its domain name
Approximately 20 types of resource records are currently used
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51. TCP/IP (continued) Some TCP/IP Application Layer Protocols Telnet
A terminal emulation protocol used to log on to remote hosts using the TCP/IP protocol suite
Using Telnet, a TCP connection is established and keystrokes on the user’s machine act like keystrokes on the remotely connected machine
Telnet is notoriously insecure
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52. TCP/IP (continued) Some TCP/IP Application Layer Protocols (continued)
File Transfer Protocol (FTP)
Used to send and receive files via TCP/IP
FTP commands will work from your operating system’s command prompt
Many FTP hosts accept anonymous logins
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53. TCP/IP (continued) Trivial File Transfer Protocol (TFTP)
Enables file transfers between computers, but it is simpler (or more trivial) than FTP
TFTP relies on UDP at the Transport layer
TFTP is useful when you need to load data or programs on a diskless workstation
TFTP does not require a user to log on to a host
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54. TCP/IP (continued) Network Time Protocol (NTP)
Used to synchronize the clocks of computers on a network
NTP depends on UDP for Transport layer services
NTP is a protocol that benefits from UDP’s quick, connectionless nature at the Transport layer
NTP is time-sensitive and cannot wait for the error checking that TCP would require
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55. TCP/IP (continued) Packet Internet Groper (PING)
A utility that can verify that TCP/IP is installed, bound to the NIC, configured correctly, and communicating with the network
PING uses ICMP services to send echo request and echo reply messages that determine the validity of an IP address
By pinging the loopback address, , you can determine whether your workstation’s TCP/IP services are running
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56. IPX/SPX
Internetwork Packet Exchange/Sequenced Packet Exchange (IPX/SPX) is a protocol originally developed by Xerox
Modified and adopted by Novell in the1980s for its NetWare network operating system
Microsoft’s implementation of IPX/SPX is called NWLink
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57. IPX/SPX (continued) The IPX and SPX Protocols
Internetwork Packet Exchange (IPX) operates at the Network layer of the OSI Model and provides logical addressing and internetworking services, similar to IP in the TCP/IP suite
IPX is a connectionless service because it does not require a session to be established before it transmits, and it does not guarantee that data will be delivered in sequence or without errors
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58. IPX/SPX (continued)
Sequenced Packet Exchange (SPX) belongs to the Transport layer of the OSI Model
A connection-oriented protocol and therefore must verify that a session has been established with the destination node before it will transmit data
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59. IPX/SPX (continued) Addressing in IPX/SPX
IPX/SPX-based networks require that each node on a network be assigned a unique address to avoid communication conflicts
IPX is the component of the protocol that handles addressing, addresses on an IPX/SPX network are called IPX addresses
IPX addresses contain two parts: the network address and the node address
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60. NetBIOS and NetBEUI
NetBIOS (Network Basic Input Output System) is a protocol originally designed for IBM to provide Transport and Session layer services for applications running on small, homogenous networks
NetBEUI can support only 254 connections, however, and does not allow for good security
Because NetBEUI frames include only Data Link layer (or MAC) addresses and not Network layer addresses, it is not routable
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61. NetBIOS and NetBEUI (continued)
Windows Internet Naming Service (WINS) - Provides a means of resolving NetBIOS names to IP addresses
A computer’s NetBIOS name and its TCP/IP host name are different entities, though you can have the same name for both
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62. NetBIOS and NetBEUI (continued)
WINS has the same relationship to NetBIOS as DNS has to TCP/IP
WINS does not assign names or IP addresses, but merely keeps track of which NetBIOS names are linked to which IP addresses
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63. Appletalk
The protocol suite originally designed to interconnect Macintosh computers
An AppleTalk network is separated into logical groups of computers called AppleTalk zones
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64. Appletalk (continued)
An AppleTalk node ID is a unique 8-bit or 16-bit number that identifies a computer on an AppleTalk network
An AppleTalk network number is a unique 16-bit number that identifies the network to which a node is connected
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65. Binding Protocols on a Windows XP Workstation
Binding is the process of assigning one network component to work with another
You can manually bind protocols that are not already associated with a network interface
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66. Summary Characteristics of TCP/IP, IPX/SPX, NetBIOS, and AppleTalk
Network protocols correlate to layers of the OSI Model
Core protocols of the TCP/IP suite and their functions
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67. Summary (continued) The most popular protocol addressing schemes
Purpose and implementation of the domain name system
Install protocols on Windows XP clients
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