Download Dynamic addressing

Local & Metropolitan
Area Networks
ACOE322
Lecture 5
TCP/IP Protocol suite
and
IP addressing
Dr. L. Christofi
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0. INTRODUCTION
We shall cover in this topic:
1. The relation of TCP/IP with internet and OSI
model
2. Internet layer
3. Transport layer and UDP
4. Application layer
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1. History and Future of TCP/IP
• The U.S. Department of
Defense (DoD) created the
TCP/IP reference model
because it wanted a
network that could survive
any conditions.
• Some of the layers in the
TCP/IP model have the
same name as layers in
the OSI model.
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Application Layer
• Handles high-level protocols, issues of
representation, encoding, and dialog control.
• The TCP/IP protocol suite combines all application
related issues into one layer and ensures this data
is properly packaged before passing it on to the
next layer.
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Transport Layer
Five basic services:
— Segmenting upper-layer application data
— Establishing end-to-end operations
— Sending segments from one end host to
another end host
— Ensuring data reliability
— Providing flow control
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Layer 4 Protocols
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Internet Layer
• The purpose of the Internet layer is to send packets from a
network node and have them arrive at the destination node
independent of the path taken.
• Internet layer protocols:
—Internet Protocol (IP)
—Internet Control Message Protocol (ICMP)
—Address Resolution Protocol (ARP)
—Reverse Address Resolution Protocol (RARP)
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Network Access Layer
• The network access layer
is concerned with all of
the issues that an IP
packet requires to
actually make a physical
link to the network
media.
• It includes the LAN and
WAN technology details,
and all the details
contained in the OSI
physical and data link
layers.
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Comparing the OSI Model and
TCP/IP Model
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Similarities of the OSI and TCP/IP
models
• Both have layers.
• Both have application layers, though they include
very different services.
• Both have comparable transport and network
layers.
• Packet-switched, not circuit-switched, technology
is assumed.
• Networking professionals need to know both
models.
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Differences of the OSI and TCP/IP
models
• TCP/IP combines the presentation and session
layer into its application layer.
• TCP/IP combines the OSI data link and physical
layers into one layer.
• TCP/IP appears simpler because it has fewer
layers.
• TCP/IP transport layer using UDP does not always
guarantee reliable delivery of packets as the
transport layer in the OSI model does.
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Internet Architecture
• Two computers, anywhere in the world, following
certain hardware, software, protocol
specifications, can communicate, reliably even
when not directly connected.
• LANs are no longer scalable beyond a certain
number of stations or geographic separation.
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2. TCP/IP Internet layer
Internet Addresses
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IP Address as a
32-Bit Binary Number
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Binary and Decimal Conversion
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IP Address Classes
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IP Address Classes
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IP Addresses as Decimal
Numbers
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Hosts for Classes of
IP Addresses
Class A (24 bits for hosts) 224 - 2* = 16,777,214 maximum
hosts
Class B (16 bits for hosts) 216 - 2* = 65,534 maximum hosts
Class C (8 bits for hosts) 28 - 2* = 254 maximum hosts
*
Subtracting the network and broadcast reserved address
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IP Addresses as Decimal
Numbers
Class D: Multicast
Class E: Research
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Network IDs and Broadcast
Addresses
An IP address such as 176.10.0.0 that has all binary 0s in
the host bit positions is reserved for the network address.
An IP address such as 176.10.255.255 that has all binary 1s
in the host bit positions is reserved for the broadcast
address.
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Private Addresses
These addresses are NEVER used on the Internet and
should never appear on the Internet.
They are used only for private networks.
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Reserved Address Space
• Network ID
• Broadcast address
• Hosts for classes of IP addresses
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Basics of Subnetting
•
•
•
•
•
Classical IP addressing
Subnetworks
Subnet mask
Boolean operations: AND, OR, and NOT
Performing the AND function
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Subnetworks
• To create a subnet address, a network
administrator borrows bits from the original host
portion and designates them as the subnet field.
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Subnetworks
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Subnet Mask
• Determines which part of an IP address is the
network field and which part is the host field
• Follow these steps to determine the subnet mask:
— 1. Express the subnetwork IP address in binary form.
— 2. Replace the network and subnet portion of the address
with all 1s.
— 3. Replace the host portion of the address with all 0s.
— 4. Convert the binary expression back to dotted-decimal
notation.
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Subnet Mask
Subnet mask in decimal = 255.255.240.0
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Boolean Operations:
AND, OR, and NOT
• Recall
— AND is like multiplication
— OR is like addition
— NOT changes 1 to 0, and 0 to 1.
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Performing the AND Function
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Range of Bits Needed to Create
Subnets
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Subnet Addresses
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Decimal Equivalents of 8-Bit
Patterns
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Creating a Subnet
• Determining subnet mask size
• Computing subnet mask and IP address
• Computing hosts per subnetwork
• Boolean AND operation
• IP configuration on a network diagram
• Host and subnet schemes
• Private addresses
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Determining Subnet Mask Size
Class B address with 8 bits borrowed for the subnet
130.5.2.144 (8 bits borrowed for subnetting) routes to
subnet 130.5.2.0 rather than just to network 130.5.0.0.
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Determining Subnet Mask Size
Class C address 197.15.22.131 with a subnet
mask of 255.255.255.224 (3 bits borrowed)
11000101
00001111
Network Field
00010110
100
00011
SN
Host Field
The address 197.15.22.131 would be on the
subnet 197.15.22.128.
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Subnetting Example
with AND Operation
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IP Configuration on a Network
Diagram
The router connects subnetworks and networks.
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Host Subnet Schemes
The number of lost IP addresses with a Class C network
depends on the number of bits borrowed for subnetting.
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Broadcast addresses exercise
Fill-in the class, subnet and broadcast IP addresses in the
following table
Address
Subnet Mask
201.222.10.60
255.255.255.248
15.16.193.6
255.255.248.0
128.16.32.13
255.255.255.252
153.50.6.27
255.255.255.128
64.10.19.152
255.255.240.0
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Class
Subnet
Broadcast
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Broadcast addresses exercise
answer
Fill-in the class, subnet and broadcast IP addresses in the
following table
Address
Subnet Mask
Class
Subnet
Broadcast
201.222.10.60
255.255.255.248
C
201.222.10.56
201.222.10.63
15.16.193.6
255.255.248.0
A
15.16.192.0
15.16.199.255
128.16.32.13
255.255.255.252
B
128.16.32.12
128.16.32.15
153.50.6.27
255.255.255.128
B
153.50.6.0
153.50.6.127
64.10.19.152
255.255.240.0
A
64.10.16.0
64.10.31.255
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Exercise 1
• Given the IP address 192.168.100.86 find
—The default mask
—The subnet mask, assuming 5 bits of subnetting
—The subnet IP address
—The broadcast address
—The first and last valid host IP addresses
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Exercise 1 answer
• Given the IP address 192.168.100.86 find
—The default mask:
It is a class C address, therefore Default mask is
255.255.255.0
—The subnet mask, assuming 5 bits of subnetting
5 bits for subnet, 3 remaining bit for host addresses, so
subnet mask is 255.255.255.248
—The subnet IP address: 192.168.100.80
—The broadcast address: 192.168.100.87
—The first and last valid host IP addresses
1st valid host address: 192.168.100.81
Last valid host address: 192.168.100.86
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Exercise 2
• Given the IP address 172.16.164.32/19 find
—The default mask
—The subnet mask
—The subnet IP address
—The broadcast address
—The first and last valid host IP addresses
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Exercise 2 answer
• Given the IP address 172.16.164.32/19 find
—The default mask
It is a class B address, so Default mask is 255.255.0.0
—The subnet mask: 255.255.224.0
—The subnet IP address: 172.16.160.0
—The broadcast address: 172.16.191.255
—The first and last valid host IP addresses
1st valid host address: 172.16.160.1
Last valid host address: 172.16.191.254
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IPv4 versus IPv6
• IP version 6 (IPv6) has been defined and developed.
• IPv6 uses 128 bits rather than the 32 bits currently used in
IPv4.
• IPv6 uses hexadecimal numbers to represent the 128 bits.
IPv4
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Obtaining an IP Address
• Static addressing
—Each individual device must be configured with an IP
address.
• Dynamic addressing
—Reverse Address Resolution Protocol (RARP)
—Bootstrap Protocol (BOOTP)
—Dynamic Host Configuration Protocol (DHCP)
—DHCP initialization sequence
—Function of the Address Resolution Protocol
—ARP operation within a subnet
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Default Gateway
A default gateway is the IP
address of the interface on the
router that connects to the
network segment on which the
source host is located.
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3. TCP/IP Transport Layer
Five basic services:
• Segmenting upper-layer application data
• Establishing end-to-end operations
• Sending segments from one end host to another
end host
• Ensuring data reliability
• Providing flow control
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Flow Control
• Avoids the problem of a host at one side of the
connection overflowing the buffers in the host at
the other side
• Ensures the integrity of the data
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Session Establishment
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Three-Way Handshake
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Windowing
• A method of controlling the amount of information
transferred end to end
• Information can be measured in terms of the
number of packets or the number of bytes
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Window Size
Larger window
sizes increase
communication
efficiency.
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Acknowledgment
• Positive acknowledgment requires a recipient to
communicate with the source, sending back an
acknowledgment message when it receives data.
• Sender keeps a record of each data packet that it
sends and expects an acknowledgment.
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Layer 4 Protocols
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TCP
• Connection oriented
• Reliable
• Divides outgoing messages into segments
• Reassembles messages at the destination station
• Resends anything not received
• Reassembles messages from incoming segments
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UDP
• Connectionless
• Unreliable
• Transmits messages (called user datagrams)
• Provides no software checking for message
delivery (unreliable)
• Does not reassemble incoming messages
• Uses no acknowledgments
• Provides no flow control
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TCP/IP Protocol Graph
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TCP Segment Format
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UDP Segment Format
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Port Numbers
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4. TCP/IP Application Layer
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Responsibilities
• Identifying and establishing the availability of
intended communication partners
• Synchronizing cooperating applications
• Establishing agreement on procedures for error
recovery
• Controlling data integrity
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Application Layer Examples
• Domain Name System (DNS)
• File Transfer Protocol (FTP)
• Hypertext Transfer Protocol (HTTP) and World
Wide Web (WWW)
• Simple Mail Transport Protocol (SNTP)
• Simple Network Management Protocol (SNMP)
• Telnet
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Domain Name System (DNS)
• To identify an entity the Internet uses the IP address, which
uniquely identifies the connection of a host to the Internet
• However, people prefer to use names instead of numeric addresses
• Therefore we need a system that can map a name to an address
or an address to a name
• When the Internet was small, mapping was done using a host file
• Today is impossible to have a single host file to relate every
address to a name and vice versa. The host file would be too large
to store in every host
• One solution is to store the entire host file in a single computer
and allow access to this centralized info to every PC that needs a
mapping – but this would create a huge amount of traffic
• Another solution is to divide this huge amount of info into smaller
parts and store each part on a different computer. In this method,
the host that needs mapping can contact the closest computer
holding the needed info.
• This method is used by the DNS system.
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Domain Name System
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FTP (1)
• File transfer protocol (FTP) is a TCP/IP client-server application for
copying files from one host to another.
• FTP requires two connections for data transfer: a control
connection and a data connection.
• FTP employs ASCII for communication between dissimilar systems.
• Prior to the actual transfer of files, the file type, data structure,
and transmission mode are defined by the client through the
control connection.
• Responses are sent from the server to the client during connection
establishment.
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FTP (2)
• There are three types of file transfer:
— A file is copied from the server to the client.
— A file is copied from the client to the server.
— A list of directories or file names is sent from the server to the
client.
• Most operating systems provide a user-friendly interface
between FTP and the user.
• Anonymous FTP provides a method of the general public to
access files on remote sites.
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SMTP
• One of the most important network services is
electronic mail (email)
• Electronic mail is used for sending a single
message that includes text, voice, video or
graphics to one or more recipients
• Simple Mail Transfer Protocol (SMTP) is the
standard mechanism for electronic mail in the
Internet
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SMTP
• E-mail servers communicate with each other using the
Simple Mail Transport Protocol (SMTP) to send and receive
mail.
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SMTP
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HTTP
•
•
•
•
•
The Hypertext Transfer Protocol (HTTP) is used mainly to access
data on the World Wide Web.
Hypertext Markup Language (HTML) is a language used to create
static Web pages.
The protocol transfers data in the form of plain text, hypertext,
audio, video and so on.
It is called HTTP because it is used in an environment where there
are rapid jumps from one document to another
HTTP functions like a combination of FTP and SMTP
- It is similar to FTP because it transfers files and uses the services of
-
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TCP (via port 80). There is no separate control connection – only
data are transferred between the client and the server
HTTP is also similar to SMTP because the data transferred between
the client and the server are similar to SMTP messages
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WWW (1)
• The HTTP is the main protocol used to access data on the World
Wide Web (WWW).
• The World Wide Web is a repository of information spread all over
the world and linked together.
• Hypertext and hypermedia are documents linked to one another
through the con-cept of pointers.
• Browsers interpret and display a Web document.
• A browser consists of a controller, client programs, and
interpreters.
• A Web document can be classified as static, dynamic, or active.
• A static document is one in which the contents are fixed and
stored in a server. The client can make no changes in the server
document.
• Any browser can read formatting instructions (tags) embedded in
an HTML document.
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WWW (2)
• A dynamic Web document is created by a server only at a browser
request.
• The Common Gateway Interface (CGI) is a standard for creating
and handling dynamic Web documents. A CGI program with its
embedded CGI interface tags can be written in a language such as
C, C++, shell script, or Perl.
• The server sends the output of the CGI program to the browser.
• The output of a CGI program can be text, graphics, binary data,
status codes, instructions, or an address of a file.
• An active document is a copy of a program retrieved by the client
and run at the client site.
• Java is a combination of a high-level programming language, a
run-time environment, and a class library that allows a
programmer to write an active document and a browser to run it.
• Java is used to created applets (small application programs).
• Java is an object-oriented typed language with a rich library of
classes.
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SNMP
• The Simple Network
Management Protocol
(SNMP) is an application
layer protocol that facilitates
the exchange of
management information
between network devices.
• An SNMP managed network
consists of the following:
— Network management
system (NMS)
— Managed device
— Agents
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Telnet
• Telnet client software provides the ability to log in to a
remote Internet host that is running a Telnet server
application and then to execute commands from the
command line.
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Exercise 3
Design a private LAN, with the following topology, that would allow
the exchange of data:
Your subnet is 192.168.200.64. You should use appropriate subnet
mask and assign appropriate IP addresses to all network elements
(routers & hosts) having in mind possible future expansion of your
network for 5 additional hosts. You have been told not to waste
unnecessary IP addresses.
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Exercise 3 (answer)
Subnet is 192.168.200.64.
Present number of hosts is 5, Number of routers is 2 and for future
expansion 5 additional hosts, makes a total of 12 addresses.
Hence use 255.255.255.240 Subnet Mask.
Broadcast IP address for this network is reserved to 192.168.200.79
therefore available IP addresses are from 192.168.200.65 to
192.168.200.78
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References
•
W. Stalling, Local and Metropolitan Area Networks,
6th edition, Prentice Hall, 2000
•
B.A. Forouzan, Data Communications and
Networking, 3rd edition, McGraw-Hill, 2004
•
W. Stallings, Data and Computer Communications,
7th edition, Prentice Hall, 2004
•
F. Halsall, Data Communications, Computer
Networks and Open Systems, 4th edition, Addison
Wesley, 1995
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