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Chapter Three
Network
Protocols
Agenda
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Attendance, and Ch.2 Quiz questions
TCP/IP Model
IP Header (Using Ethereal to analyze
the IP header)
TCP Header (using Ethereal to
analyze the TCP Header)
Address Resolution Protocol Lab
Introduction to Protocols
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Protocol
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Rules network uses to transfer data
Protocols that can span more than one
LAN segment are routable
Multiprotocol network
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Network using more than one protocol
TCP/IP
OSI Model
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Transmission
Control
Protocol/Internet
Protocol (TCP/IP)
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Suite of small,
specialized
protocols called
subprotocols
TCP/IP
TCP/IP model
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File Transfer Protocol (FTP)
Hypertext Transfer Protocol (HTTP)
Simple Mail Transfer Protocol (SMTP)
Domain Name System (DNS)
Trivial File Transfer Protocol (TFTP)
The common transport layer
protocols include:
 Transport Control Protocol (TCP)
 User Datagram Protocol (UDP)
The primary protocol of the
Internet layer is:
 Internet Protocol (IP)
TCP/IP model
TCP/IP Compared to the
OSI Model
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Application layer roughly corresponds to
Session, Application, and Presentation layers
of OSI Model
Transport layer roughly corresponds to
Transport and session layers of OSI Model
Internet layer is equivalent to Network layer of
OSI Model
Network Interface layer roughly corresponds to
Data Link and Physical layers of OSI Model
The TCP/IP Core Protocols
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Certain subprotocols of TCP/IP suite
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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
Internet Protocol (IP)
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Provides information about how and where
data should be delivered
Subprotocol that enables TCP/IP to
internetwork
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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
Internet Protocol (IP)
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IP datagram
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IP portion of TCP/IP frame that acts as an envelope for data
Contains information necessary for routers to transfer data
between subnets
IP header format
IP header format: Version
• 4 bits.
• Indicates the version of
IP currently used.
– IPv4 : 0100
– IPv6 : 0110
IP header format: Header length
• 4 bits.
• IP header length : Indicates the
datagram header length in 32 bit
words (4 bits), and thus points to
the beginning of the data.
IP header format: Service type
• 8 bits.
• Specifies the level of importance
that has been assigned by a
particular upper-layer protocol.
• Precedence.
• Reliability.
• Speed.
IP header format: Total length
• 16 bits.
• Specifies the length of the
entire IP packet, including
data and header, in bytes.
IP header format: Identification
• 16 bits.
• Identification contains an integer
that identifies the current datagram.
• Assigned by the sender to aid in
assembling the fragments of a
datagram.
IP header format: Flags
• 3 bits.
• The second bit specifying whether the
packet can be fragmented .
• The last bit specifying whether the packet
is the last fragment in a series of
fragmented packets.
IP header format: Fragment offset
• 13 bits.
• The field that is used to help piece together
datagram fragments.
• The fragment offset is measured in units of
8 octets (64 bits).
• The first fragment has offset zero.
IP header format: Time to Live
• 8 bits.
• Time-to-Live maintains a counter that
gradually decreases to zero, at which point
the datagram is discarded, keeping the
packets from looping endlessly.
IP header format: Protocol
• 8 bits.
• Indicates which upper-layer protocol receives
incoming packets after IP processing has
been completed
• 06 : TCP
• 17 : UDP
IP header format: Header checksum
• 16 bits.
• A checksum on the header only,
helps ensure IP header integrity.
IP header format: Addresses
• 32 bits each.
• Source IP Address
• Destination IP Address
IP header format: Options
• Variable length.
• Allows IP to support various options,
such as security, route, error report ...
IP header format: Padding
• The header padding is used to ensure
that the internet header ends on a 32 bit
boundary.
Ethereal Lab (Analyzing the IP
Header)
Use Ethereal to capture some frames. Open one of
the frames and look at the IP header. Based on
what you see, try to answer the following:
 What is the IP version?
 What is the IP header length?
 What is the type of Service?
 What is the time to live?
 What is the protocol?
 What is the source IP address?
 What is the destination IP address?
Internet Protocol (IP)
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IP is an unreliable, connectionless
protocol, which means it does not
guarantee delivery of data
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Connectionless
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Allows protocol to service a request without
requesting verified session and without
guaranteeing delivery of data
Transport Control Protocol
(TCP)
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TCP
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Provides reliable data delivery services
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Connection-oriented subprotocol
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Requires establishment of connection
between communicating nodes before
protocol will transmit data
TCP segment
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Holds TCP data fields
Becomes encapsulated by IP datagram
Transport Control Protocol
(TCP)
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Port
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Address on host where application makes itself
available to incoming data
Ethereal Lab (Analyzing the
TCP Header)
Use Ethereal to capture some frames. Open
one of the frames and look at the TCP
header. Based on what you see, try to
answer the following:
 What is the source Port?
 What is the destination Port?
 What is the sequence Number?
 What Is the Acknowledgement Number?
 What is the header Length?
Additional Core Protocols of the
TCP/IP Suite
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User Datagram Protocol (UDP)
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Internet Control Message Protocol (ICMP)
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Connectionless transport service
Notifies sender of an error in transmission process
and that packets were not delivered
Address Resolution Protocol (ARP)
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Obtains MAC address of host or node
Creates local database mapping MAC address to
host’s IP address
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ARP Lab
Agenda
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Attendance and questions about last
week’s material.
TCP/IP Application Layers
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FTP Lab
Telnet Lab
Break
Binary and hexadecimal conversion
TCP/IP Application Layer
Protocols
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Telnet
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File Transfer Protocol (FTP)
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Used to send and receive files via TCP/IP
Simple Mail Transfer Protocol (SMTP)
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Used to log on to remote hosts using TCP/IP
protocol suite
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)
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Manages devices on a TCP/IP network
Labs
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FTP Lab
Telnet Lab
Addressing in TCP/IP
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IP Address
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Logical address used in TCP/IP
networking
Unique 32-bit number
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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
Addressing in TCP/IP
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Though 8 bits have 256 possible combinations, only
the numbers 1 through 254 are used to identify
networks and hosts
Number 255 is reserved for broadcasts
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Broadcast are transmissions to all stations on a network
Addressing in TCP/IP
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Loopback address
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IP address reserved for communicating from
a node to itself
Value of the loopback address is always
127.0.0.1
Internet Corporation for Assigned Names
and Numbers (ICANN)
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Non-profit organization currently designated
by U.S. government to maintain and assign
IP addresses
Addressing in TCP/IP
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Firewall
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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
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Computer connected to a network using the
TCP/IP protocol
Addressing in TCP/IP
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In IP address 131.127.3.22, to convert
the first octet (131) to a binary number:
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On Windows 2000, click Start, point to
Programs, point to Accessories, then
click Calculator
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Click View, then click Scientific (make
sure Dec option button is selected)
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Type 131, then click Bin option button
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The binary equivalent of number 131, 10000011,
appears in the display window
Addressing in TCP/IP
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Static IP address
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IP address manually assigned to a device
Dynamic Host Configuration Protocol
(DHCP)
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Application layer protocol
Manages dynamic distribution of IP
addresses on a network
Viewing Current IP Information
Viewing Current IP Information
Addresses and Names
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In addition to using IP addresses,
TCP/IP networks use names for
networks and hosts
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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)
NetBIOS and NetBEUI
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Network Basic Input Output System
(NetBIOS)
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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
NetBIOS and NetBEUI
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NetBIOS Enhanced User Interface
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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
NetBIOS Addressing
Installing Protocols
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After installing protocols, they must be
binded to NICs and services they run
on or with
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Binding
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Process of assigning one network component
to work with another
Chapter Summary
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Protocols define standards for
communication between nodes on a
network
Protocols vary in speed, transmission
efficiency, utilization of resources, ease
of setup, compatibility, and ability to
travel between one LAN segments
TCP/IP is the most popular network
protocol
Chapter Summary
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TCP/IP suite of protocols can be divided
into four layers roughly corresponding to
seven layers of OSI Model
Operating in Transport or Network layers
of OSI Model, TCP/IP core protocols
provide communications between hosts
on a network
Each IP address is a unique 32-bit
number, divided into four groups of octets
separated by periods
Chapter Summary
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Every host on a network must have a
unique number
Internetworking Packet
Exchange/Sequenced Packet Exchange
(IPX/SPX) is a protocol originally
developed by Xerox then modified and
adopted by Novell in the 1980s for its
NetWare network operating system
Core protocols of IPX/SPX provide
services at Transport and Network layers
of OSI Model
Chapter Summary
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Addresses on an IPX/SPX network are
called IPX addresses
Network Basic Input Output System
(NetBIOS) was originally developed by
IBM to provide Transport and Session
layer services
Microsoft adopted NetBIOS as its
foundation protocol, then added an
Application layer component called
NetBIOS Enhanced User Interface
(NetBEUI)
Chapter Summary
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To transmit data between network nodes,
NetBIOS needs to know how to reach
each workstation
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Each workstation must have a NetBIOS
name
AppleTalk is the the protocol suite used to
interconnect Macintosh computers
An AppleTalk network is separated into
logical groups of computers called
AppleTalk zones
Chapter Summary
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Though Apple has improved AppleTalk’s
ability to use different network models and
span network segments, it remains unsuited
to large LANs or WANs
In addition to zone names, AppleTalk uses
node IDs and network numbers to identify
computers on a network
Though some protocols (such as NetBIOS)
require no configuration after installation,
others (such as TCP/IP) do require
configuration
Next Week
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Make sure that you have taken chapter 3
Quiz online
Make sure that you have read chapter 11
Download packet tracer from my web site
and install it at home. Try to read the tutorial
to gain some understanding on how it
works. You will use this program in your
project