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The TCP/IP Protocol. Introduction To TCP/IP. Transmission Control Protocol/Internet Protocol (TCP/IP) Most commonly used network protocol suite today Wide vendor support Open protocol Provides access to Internet services Windows Server 2003 Can use several protocols

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introduction to tcp ip
Introduction To TCP/IP
  • Transmission Control Protocol/Internet Protocol (TCP/IP)
    • Most commonly used network protocol suite today
    • Wide vendor support
    • Open protocol
    • Provides access to Internet services
  • Windows Server 2003
    • Can use several protocols
    • Many of its main features require the use of TCP/IP
internet history
Internet History

1961-1972: Early packet-switching principles

1961: Kleinrock - queueing theory shows ` effectiveness of packet-switching

1964: Baran - packet-switching in military nets

1967: ARPAnet conceived by Advanced Research Projects Agency

1969: first ARPAnet node operational

1972: ARPAnet demonstrated publicly, NCP (Network Control Protocol) first host-host protocol, first e- mail program. ARPAnet has 15 nodes

internet history1
Internet History

1972-1980: Internetworking, new and proprietary nets

1970: ALOHAnet satellite network in Hawaii

1973: Metcalfe’s PhD thesis proposes Ethernet

1974: Cerf and Kahn - architecture for interconnecting networks

late70’s: proprietary architectures,DECnet, SNA, XNA

1979: ARPAnet has 200 nodes

internet history2
Internet History

1972-1980: Internetworking, new and proprietary nets

  • Cerf and Kahn’s internetworking principles:
    • minimalism, autonomy-no internal changes required to interconnect networks
    • best effort service model
    • stateless routers
    • decentralized control
  • define today’s Internet architecture
internet history3
Internet History

1980-1990: new protocols, a proliferation of networks

1983: deployment of TCP/IP

1982: SMTP e-mail protocol defined

1983: DNS defined for name-to-IP- address translation

1985: FTP protocol defined

1988: TCP congestion control

internet history4
Internet History

1980-1990: new protocols, a proliferation of networks

US networks: Csnet, BITnet, NSFnet, Minitel

100,000 hosts connected to confederation of networks

internet history5
Internet History

1990, 2000’s: commercialization, the Web, new apps

  • Early 1990’s: ARPAnet decommissioned
  • 1991: NSF lifts restrictions on commercial use of NSFnet (decommissioned, 1995)
  • early 1990s: Web
    • hypertext [Bush 1945, Nelson 1960’s]
    • HTML, HTTP: Berners-Lee
    • 1994: Mosaic, later Netscape
    • late 1990’s: commercialization of the Web
internet history6
Internet History

1990, 2000’s: commercialization, the Web, new apps

  • Late 1990’s – 2000’s:
  • more killer apps: instant messaging,peer-2-peer file sharing (e.g., Naptser)
  • network security to forefront
  • est. 50 million host, 100 million+ users
  • backbone links running at Gbps
  • now: 10-40 Gbps (youtube, social networking)
the capital i internet
The (capital “I”) Internet

The world-wide network of TCP/IP networks

Different people or organisations own different parts

Different parts use different technologies

Interconnections between the parts

Interconnections require agreements

sale/purchase of service

contracts

“peering” agreements

No central control or management

the principle of internetworking
The principle of “Internetworking”

We have lots of little networks

Many different owners/operators

Many different types

Ethernet, dedicated leased lines, dialup, optical, broadband, wireless, ...

Each type has its own idea of low level addressing and protocols

We want to connect them all together and provide a unified view of the whole lot (treat the collection of networks as a single large internetwork)‏

what s the internet
What’s the Internet

millions of connected computing devices: hosts, end-systems

PC’s workstations, servers

PDA’s phones,

communication links

fiber, copper, radio, satellite

routers: forward packets (chunks) of data through network

router

workstation

server

mobile

local ISP

regional ISP

company

network

tcp ip architecture overview
TCP/IP Architecture Overview
  • The TCP/IP model can be broken down into four layers:
    • Application
    • Transport
    • Internet
    • Physical Network Interface
  • Application layer provides access to network resources. It defines rules, commands, and procedures for client to talk to a service running on a server
tcp ip architecture overview continued
TCP/IP Architecture Overview (continued)
  • Transport layer is responsible for preparing data ready to be transported across the network
  • Internet layer is responsible for logical addressing and routing
  • Physical Network Interface layer consists of the network card driver and the network card itself
the tcp ip model
The TCP/IP Model

SMTP

HTTP

FTP

Telnet

DNS

Audio

Video

TCP

UDP

RTP

IP

Ethernet

ATM

Optics

ADSL

3G

PPP

Satellite

Application layer

Transport layer

Network layer

Physical and Data link layer

layer interaction tcp ip model
Layer Interaction:TCP/IP Model

Application

Application

TCP or UDP

TCP or UDP

IP

IP

IP

IP

Link

Link

Link

Link

Link

Link

Physical

Physical

Physical

Router

Host

Host

Router

layer interaction the application layer
Layer Interaction:The Application Layer

Application

Application

TCP or UDP

TCP or UDP

IP

IP

IP

IP

Link

Link

Link

Link

Link

Link

Physical

Physical

Physical

Applications behave as if they can talk to each other, but in reality the application at each side talks to the TCP or UDP service below it.

The application layer doesn't care about what happens at the lower layers, provided the transport layer carries the application's data safely from end to end.

Router

Host

Host

Router

layer interaction the transport layer
Layer Interaction:The Transport Layer

Application

Application

TCP or UDP

TCP or UDP

IP

IP

IP

IP

Link

Link

Link

Link

Link

Link

Physical

Physical

Physical

The transport layer instances at the two ends act as if they are talking to each other, but in reality they are each talking to the IP layer below it. The transport layer doesn't care about what the application layer is doing above it.

The transport layer doesn't care what happens in the IP layer or below, as long as the IP layer can move datagrams from one side to the other.

Router

Host

Host

Router

layer interaction the network layer ip
Layer Interaction:The Network Layer (IP)

Application

Application

TCP or UDP

TCP or UDP

IP

IP

IP

IP

Link

Link

Link

Link

Link

Link

Physical

Physical

Physical

The IP layer has to know a lot about the topology of the network (which host is connected to which router, which routers are connected to each other), but it doesn't care about what happens at the upper layers.

The IP layer works forwards messages hop by hop from one side to the other side.

Router

Host

Host

Router

layer interaction link and physical layers
Layer Interaction:Link and Physical Layers

Application

Application

TCP or UDP

TCP or UDP

IP

IP

IP

IP

Link

Link

Link

Link

Link

Link

Physical

Physical

Physical

The link layer doesn't care what happens above it, but it is very closely tied to the physical layer below it.

All links are independent of each other, and have no way of communicating with each other.

Router

Host

Host

Router

a flow of application messages across tcp ip layers

Message

Layers

Application

Messages (UDP) or Streams (TCP)

Transport

UDP or TCP segment

Internet

IP Packets

PhysicalNetwork interface

Network-specific frames

Underlying network

A Flow of Application messages across TCP/IP layers
encapsulation of a message transmitted via tcp over an ethernet

Application message

port

TCP header

TCP

IP header

Ethernet header

IP

Ethernet frame

Encapsulation of a message transmitted via TCP over an Ethernet
layering physical communication
Layering: physical communication

application

transport

network

link

physical

network

link

physical

application

transport

network

link

physical

data

data

application

transport

network

link

physical

application

transport

network

link

physical

application layer protocols
Application Layer Protocols
  • There are many Application layer protocols, each of which is associated with a client application and service provided by a server (Client/Server Model)
    • HTTP
    • FTP
    • TELNET
    • SMTP
    • POP3
    • IMAP4
application layer protocols1
Application Layer Protocols

HTTP

  • Hypertext Transfer Protocol (HTTP) is the most common protocol used on the Internet today
  • HTTP defines the commands that Web browsers can send and how Web servers are capable of responding

FTP

  • File Transfer Protocol (FTP) is file-sharing protocol
  • FTP is implemented in stand-alone FTP clients as well as in Web browsers
  • It is safe to say that most FTP users today are using Web browsers
application layer protocols2
Application Layer Protocols

TELNET

  • Telnet is a terminal emulation protocol that is primarily used to connect remotely to UNIX and Linux Systems
  • The Telnet protocol specifies how a telnet server and telnet client communicate
application layer protocols3
Application Layer Protocols

SMTP

  • Simple Mail Transfer Protocol (SMTP) is used to send and receive e-mail messages between e-mail servers that are communicating
  • It is used by e-mail client software, such as Outlook Express, to send messages to the server
  • SMTP is never used to retrieve e-mail from a server when you are reading it
  • Other protocols control the reading of e-mail messages
slide30

Application Layer Protocols

POP3

  • Post Office Protocol version 3 (POP3) is the most common protocol used for reading e-mail messages
  • This protocol has commands to download messages and delete messages from the mail server
  • POP3 does not support sending messages
  • POP3 supports only a single inbox and does not support multiple folders for storage on the server
slide31

Application Layer Protocols

IMAP4

  • Internet Message Access Protocol version 4 (IMAP4) is another common protocol used to read e-mail messages
  • IMAP4 can download message headers only and allow you to choose which messages to download
  • IMAP4 allows for multiple folders on the server side to store messages
transport layer protocols
Transport Layer Protocols
  • Transport layer protocols (TCP & UDP) are responsible for getting data ready to move across the network
  • The most common task performed by Transport layer protocols is breaking entire messages down into segments suitable to form packets
  • Transport layer protocols use port numbers
  • When a segment is addressed to a particular port, the Transport layer protocol knows to which service to deliver the packet
slide33
TCP
  • Transmission Control Protocol (TCP) is the most commonly used Transport layer protocol for most Internet services
  • TCP is connection-oriented and reliable
  • Connection-oriented means that TCP creates and verifies a connection with a remote host before sending information
  • Verifies that the remote host exists and is willing to communicate before starting the conversation
  • Provides flowcontrol, segmentation, and error control
slide34
TCP

Connection-oriented

Establishes a connection before transmitting data

Three-way handshake

SYN

SYN/ACK

ACK

slide35
TCP

Error control & Flow control

Require acknowledgements from receiver to ensure data was received correctly

Checksum

Unique character string allowing receiving node to determine if arriving data unit exactly matches data unit sent by source

Ensures data integrity

Send data, wait for ACK

ACK

Send more data, wait for ACK

slide36
Segmentation

Breaking large data units received from Session layer into multiple smaller units called segments

Increases data transmission efficiency

MTU (maximum transmission unit): Largest data unit network will carry (Ethernet default: 1500 bytes)

Sequencing

Method of identifying segments belonging to the same group of subdivided data

Reassembly

Process of reconstructing segmented data units

TCP

transport layer cont d
Transport Layer (cont’d.)

Figure 2-2 Segmentation and reassembly

tcp segment

1

2

3

4

5

6

7

8

9

10

11

User Data

TCP Segment

1 Source ID or port 16 bits

2 Destination ID or port 16 bits

3 Sequence number 32 bits

4 ACK number 32 bits

5 Header length 4 bits

6 Unused 6 bits

7 Flags 6 bits

8 Flow control 16 bits

9 CRC 16 16 bits

10 Urgent pointer 16 bits

11 Options 16 bits

slide39
UDP
  • User Datagram Protocol (UDP)
    • Not as commonly used as TCP
    • Used for different services
    • Connectionless and unreliable
  • UDP is the appropriate if
    • Unconcerned about missing packets
    • Want to implement reliability in a special way
  • Streaming audio and video are in this category
udp segment

1

2

3

4

User Data

UDP – Segment
  • Source ID or port
  • Destination ID or port
  • Length
  • 4 Checksum
tcp versus udp
TCP versus UDP
  • TCP is connection-oriented and reliable
    • Like registered mail
  • UDP is connectionless and unreliable
    • Like sending a message split on several postcards and assuming that the receiver will be able to put the message together
internet layer protocols
Internet Layer Protocols
  • Internet layer protocols are responsible for all tasks related to logical addressing
  • An IP address is a logical address
  • Any protocol that is aware of other networks exists at this layer
  • Each Internet layer protocol is very specialized
  • They include: IP, RIP and OSPF, ICMP, IGMP, and ARP
internet layer protocols1
Internet Layer Protocols

IP

  • Internet Protocol (IP) is responsible for the logical addressing of each packet created by the Transport layer to produce a complete IP Packet
  • As each packet is built, IP adds the source and destination IP address to the IP packet

ICMP

  • Internet Control Messaging Protocol (ICMP) is used to send IP error and control messages between routers and hosts
  • The most common use of ICMP is the ping utility
ip packet version 4

IP4

1

2

3

4

5

6

7

8

9

10

11

12

13

14

IP Packet version 4

1 Version number 4 bits

2 Header length 4 bits

3 Type of Service 8 bits

4 Total length 16 bits

5 Identifiers 16 bits

6 Flags 3 bits

7 Packet offset 13 bits

8 Hop limit 8 bits

9 Protocol 8 bits

10 CRC 16 16 bits

11 Source address 32 bits

12 Destination Address 32 bits

13 Options varies

14 User data varies

internet layer protocols2
Internet Layer Protocols

IGMP

  • Internet Group Management Protocol (IGMP) is used for the management of multicast groups
  • Hosts use IGMP to inform routers of their membership in multicast groups
  • Routers use IGMP to announce that their networks have members in particular multicast groups
  • The use of IGMP allows multicast packets to be distributed only to routers that have interested hosts connected
internet layer protocols3
Internet Layer Protocols

ARP

  • Address Resolution Protocol (ARP) is used to convert logical IP addresses to physical MAC addresses
  • This is an essential part of the packet delivery process
network interface layer protocols
Network Interface Layer Protocols
  • Most of the common Network Interface layer protocols are defined by the Institute of Electrical and Electronics Engineers (IEEE)
ip addresses
IP Addresses
  • Internet Protocol (IP):
    • a protocol used in the internet layer.
    • IP makes use of the existing networks to deliver information, where these networks may use a variety of protocols.
  • Each computer has two addresses:
    • hardware address: used by the underlying network protocol for deliver data frame;
    • IP address: used by the internetworking protocols for deliver IP Packet.
  • Hardware address is also known as physical address.
types of addresses used on hosts
Types of addresses used on hosts

Address Example Software Example Address

Application Layer Web browser www.cba.uga.edu

Network Layer TCP/IP 128.192.98.5:80

Data Link Layer Ethernet 00-0C-00-F5-03-5A

ip addresses1
IP Addresses

IP Addressing Scheme

  • Each computer / router is assigned a unique IP address having 32 bits.
  • Each IP address has two parts:
    • The prefix (network ID or NetID) specifies the network to which the computer is attached.
    • The suffix (HostID) specifies a particular computer on a network.
  • Problem
    • Given only 32 bits, how many bits should be allocated to the prefix and the suffix?
      • around 4 billion addresses.
ip addresses2
IP Addresses

IP Addressing Scheme

  • Considerations
    • If the prefix has many bits (large prefix, small suffix), there are many networks you can built but each network can only have a few computers.
    • If the prefix has a few bits (small prefix, large suffix), there are only few networks you can built but each network can have many computers.
subnet masks
Subnet Masks
  • A subnet mask defines which part of its IP address is the network ID and which part is the host ID
  • Subnet masks are composed of four octets just like an IP address
  • Wherever there is a 255 in the subnet mask, that octet is part of the network ID
  • Wherever there is a 0 in the subnet mask, that octet is part of the host ID
subnet masks continued
Subnet Masks (continued)
  • A computer uses its subnet mask to determine
    • Which network it is on
    • Whether other computers are on the same network or a different network
  • If two computers on the same network are communicating, then they can deliver packets directly to each other
  • If two computers are on different networks, they must use a router to communicate
ip address classes
IP Address Classes
  • The IP addressing scheme defines three primary classes (A,B,C), where each class has a distinct prefix/suffix size, and two reserved classes (D&E).
  • The internet can accommodate large networks, medium networks, and small networks.
  • Classes A, B, C are the primary classes. The IP addresses of computers and routers belong to these classes.
  • Class D is used for multicasting. When a packet is sent to an IP multicast address, all the computers sharing this address will receive this packet.
  • Class E addresses are considered experimental and are not used
slide59
In each primary class, the number of networks and the number of computers per network are as follows:
  • Each packet sent across the internet contains:
    • the IP address of the source, and
    • the IP address of the destination.
slide60
Dotted Decimal Notation
    • Commonly we use the dotted decimal notation to represent the 32-bit IP address.
      • more convenient for human to manipulate
    • Each octet (8-bit) is expressed as a decimal value, and adjacent decimal values are separated by a dot.
    • Example:
slide61
Loopback address
    • 127.x.x.x
    • intended for use in testing TCP/IP and for inter-process communication on the local computer
  • Other special value of primary classes:
slide62
Assigning IP Addresses
  • Assigning Prefix Address
    • Each network must have a unique prefix address throughout an internet.
    • To connect a network to the global internet, an organization obtains a unique prefix address from the Internet Service Provider (ISP).
    • In turn, the ISP coordinates with a central organization (the Internet Assigned Number Authority (IANA, on or before 1998); the Internet Corporation for Assigned Names and Numbers (ICANN, after 1998)) to ensure the uniqueness of the prefix.
    • To connect a network to a private internet (Intranet), the organization can determine the prefix while ensuring its uniqueness.
slide63
Assigning IP Addresses
  • Assigning Suffix Address
    • Each computer must have a unique suffix address in the same network; while two computers in two different networks can have identical suffix address or HostID.
    • If the suffix is 00…0 or 11…1, the corresponding IP addresses have special meaning. Do not assign these suffixes.
      • An IP address with suffix equal to 00…0 is used to refer to the network itself.
      • An IP address with suffix equal to 11…1 is a directed broadcast address, i.e., it refers to all hosts on the network.
slide64
Example
    • An organization wants to form a private TCP/IP internet with four networks, where one network is large (with many computers), two are medium, and one is small.
    • Firstly, assign a unique prefix to each network:
      • Assign a class A prefix for the large network (say, 10).
      • Assign a class B prefix for each of the two medium networks (say, 128.10 and 128.11).
      • Assign a class C prefix for the small network (say, 192.5.48).
    • Secondly, assign a unique suffix to each computer within each network:
private ip addresses
Private IP Addresses
  • You can use these addresses on any private LAN.
  • You CANNOT use them on the internet.
  • Internet routers will block them.
default gateway
Default Gateway
  • Default gateway is another term for router
  • If a computer does not know how to deliver a packet, it gives the packet to the default gateway to deliver
  • Routers can distinguish multiple networks and how to move packets between them
  • Routers can also figure out the best path to use to move a packet between different networks
classful ip address
Classful IP Address

A classful network had a “natural” or “implied” prefix length or netmask:

Class A: prefix length /8 (netmask 255.0.0.0)‏

Class B: prefix length /16 (netmask 255.255.0.0)‏

Class C: prefix length /24 (netmask 255.255.255.0)‏

Modern (classless) routing systems have explicit prefix lengths or netmasks

You can't just look at an IP address to tell what the prefix length or netmask should be. Protocols and configurations need explicit netmask or prefix length.

classless addressing
Classless addressing

Internet routing and address management today is classless

CIDR = Classless Inter-Domain Routing

routing does not assume that class A, B, C implies prefix length /8, /16, /24

An ISP gets a large block of addresses

e.g., a /16 prefix, or 65536 separate addresses

classless addressing1
Classless addressing

Allocate smaller blocks to customers

e.g., a /26 prefix (64 addresses) to 4 customers for their medium public networks, a /28 prefix (16 addresses) to 32 customers for their medium public networks, and a /29 prefix (8 addresses) to another 64 customers for their small public networks (and some space left over for other customers)

binary presentation of classless ip
Binary presentation of Classless IP

1111 1111

1111 1111

1 000 0000

0000 0000

1000 1001

1001 1110

1 000 0000

0000 0000

1111 1111

1111 1111

0000 0000

0000 0000

1100 0110

1000 0110

0000 0000

0000 0000

1111 1111

1111 1111

1111 1111

11 00 0000

1100 1101

0010 0101

1100 0001

10 00 0000

  • 137.158.128.0/17 (netmask 255.255.128.0)‏
  • 198.134.0.0/16 (netmask 255.255.0.0)‏
  • 205.37.193.128/26 (netmask 255.255.255.192)
classless addressing exercise
Classless addressing exercise

Consider the address block 133.27.162.0/28 and 133.27.163.48/29.

What are the IP addresses range can you obtain from each block?

in prefix length notation

netmasks in decimal

IP address ranges

What blocks are still available (not yet allocated)?

sockets and ports1
Sockets and Ports

Processes assigned unique port numbers

Process’s socket

Port number plus host machine’s IP address

Port numbers

Simplify TCP/IP communications

Ensures data transmitted correctly to the specific application among multiple applications running on same host

Example

Telnet port number: 23

IPv4 host address: 10.43.3.87

Socket address: 10.43.3.87:23

sockets and ports cont d
Sockets and Ports (cont’d.)

Figure 4-12 A virtual connection for the Telnet service

sockets and ports cont d1
Sockets and Ports (cont’d.)

Port number range: 0 to 65535

Three types

Well Known Ports

Range: 0 to 1023

Operating system or administrator use

Registered Ports

Range: 1024 to 49151

Network users, processes with no special privileges

Dynamic and/or Private Ports

Range: 49152 through 65535

No restrictions

sockets and ports cont d2
Sockets and Ports (cont’d.)

Table 4-3 Commonly used TCP/IP port numbers