1 06/02/2006 1 Dr. L. Christofi 1 Local Local Local Local & Metropolitan Metropolitan Metropolitan Metropolitan Area Networks Area Networks Area Networks Area Networks ACOE322 Lecture 5 TCP/IP Protocol suite and IP addressing Dr. L. Christofi 2 0. INTRODUCTION INTRODUCTION INTRODUCTION 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 Dr. L. Christofi 3 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.
Transcript
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Local Local Local Local &&&& Metropolitan Metropolitan Metropolitan Metropolitan
Area NetworksArea NetworksArea NetworksArea Networks
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: MulticastClass E: Research
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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.
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.
Network IDs and Broadcast
Addresses
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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 in decimal = 255.255.240.0
Subnet Mask
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• Recall
— AND is like multiplication
— OR is like addition
— NOT changes 1 to 0, and 0 to 1.
Boolean Operations:
AND, OR, and NOT
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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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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.
Determining Subnet Mask Size
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The address 197.15.22.131 would be on the
subnet 197.15.22.128.
Host FieldSNNetwork Field
00011100000101100000111111000101
Class C address 197.15.22.131 with a subnet mask of 255.255.255.224 (3 bits borrowed)
Determining Subnet Mask Size
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Subnetting Example
with AND Operation
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The router connects subnetworks and networks.
IP Configuration on a Network
Diagram
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The number of lost IP addresses with a Class C network depends on the number of bits borrowed for subnetting.
Host Subnet Schemes
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Broadcast addresses exercise
Address Subnet Mask Class Subnet Broadcast
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
Fill-in the class, subnet and broadcast IP addresses in the following table
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Broadcast addresses exercise
answer
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
Fill-in the class, subnet and broadcast IP addresses in the following table
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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.
A default gateway is the IPaddress of the interface on the router that connects to the network segment on which the source host is located.
Default Gateway
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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
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 serverdocument.
• 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 asC, 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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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 subnetmask 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.
Exercise 3
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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
Exercise 3 (answer)
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References
• W. Stalling, Local and Metropolitan Area Networks, 6th edition, Prentice Hall, 2000
• F. Halsall, Data Communications, Computer Networks and Open Systems, 4th edition, Addison Wesley, 1995
• B.A. Forouzan, Data Communications and Networking, 3rd edition, McGraw-Hill, 2004
• W. Stallings, Data and Computer Communications, 7th edition, Prentice Hall, 2004
