Network+ Guide to Networks
Third Edition
Chapter 4:
Network Protocols
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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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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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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Introduction To Protocols
• Networks running more than one protocol are called
multiprotocol networks
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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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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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TCP/IP (continued)
• 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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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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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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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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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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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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TCP/IP (continued)
• Acknowledgment number (ACK)
• TCP header length
• Reserved
• Flags
• Sliding-window size (or window)
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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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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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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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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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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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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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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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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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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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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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TCP/IP (continued)
• Addressing in TCP/IP
• Two kinds of addresses: Logical or physical
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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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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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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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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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TCP/IP (continued)
• The command used to view IP information
on a Windows XP workstation is ipconfig
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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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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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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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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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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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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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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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TCP/IP (continued)
• Terminating a DHCP Lease
• 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
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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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TCP/IP (continued)
• Registered Ports are in the range of 1024 to
49151. These ports are accessible to network
users and processes that do not have special
administrative privileges
• Dynamic and/or Private Ports are those from
49152 through 65535 and are open for use
without restriction
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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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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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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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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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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, www.novell.com, “com” is
the top-level domain (TLD), “novell” is the
second-level domain, and “www” is the thirdlevel domain
• Domain names must be registered with an Internet
naming authority that works on behalf of ICANN
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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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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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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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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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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 Internetconnected device to its domain name
• Approximately 20 types of resource records are
currently used
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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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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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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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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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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, 127.0.0.1, you
can determine whether your workstation’s TCP/IP
services are running
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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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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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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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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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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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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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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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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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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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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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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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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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