Your SlideShare is downloading. ×
0
Lecture 2 -_understanding_networks_2013
Lecture 2 -_understanding_networks_2013
Lecture 2 -_understanding_networks_2013
Lecture 2 -_understanding_networks_2013
Lecture 2 -_understanding_networks_2013
Lecture 2 -_understanding_networks_2013
Lecture 2 -_understanding_networks_2013
Lecture 2 -_understanding_networks_2013
Lecture 2 -_understanding_networks_2013
Lecture 2 -_understanding_networks_2013
Lecture 2 -_understanding_networks_2013
Lecture 2 -_understanding_networks_2013
Lecture 2 -_understanding_networks_2013
Lecture 2 -_understanding_networks_2013
Lecture 2 -_understanding_networks_2013
Lecture 2 -_understanding_networks_2013
Lecture 2 -_understanding_networks_2013
Lecture 2 -_understanding_networks_2013
Lecture 2 -_understanding_networks_2013
Lecture 2 -_understanding_networks_2013
Lecture 2 -_understanding_networks_2013
Lecture 2 -_understanding_networks_2013
Lecture 2 -_understanding_networks_2013
Lecture 2 -_understanding_networks_2013
Lecture 2 -_understanding_networks_2013
Lecture 2 -_understanding_networks_2013
Lecture 2 -_understanding_networks_2013
Lecture 2 -_understanding_networks_2013
Lecture 2 -_understanding_networks_2013
Lecture 2 -_understanding_networks_2013
Lecture 2 -_understanding_networks_2013
Lecture 2 -_understanding_networks_2013
Lecture 2 -_understanding_networks_2013
Lecture 2 -_understanding_networks_2013
Lecture 2 -_understanding_networks_2013
Lecture 2 -_understanding_networks_2013
Lecture 2 -_understanding_networks_2013
Lecture 2 -_understanding_networks_2013
Lecture 2 -_understanding_networks_2013
Lecture 2 -_understanding_networks_2013
Lecture 2 -_understanding_networks_2013
Lecture 2 -_understanding_networks_2013
Lecture 2 -_understanding_networks_2013
Lecture 2 -_understanding_networks_2013
Lecture 2 -_understanding_networks_2013
Lecture 2 -_understanding_networks_2013
Lecture 2 -_understanding_networks_2013
Lecture 2 -_understanding_networks_2013
Lecture 2 -_understanding_networks_2013
Lecture 2 -_understanding_networks_2013
Upcoming SlideShare
Loading in...5
×

Thanks for flagging this SlideShare!

Oops! An error has occurred.

×
Saving this for later? Get the SlideShare app to save on your phone or tablet. Read anywhere, anytime – even offline.
Text the download link to your phone
Standard text messaging rates apply

Lecture 2 -_understanding_networks_2013

227

Published on

Published in: Technology
0 Comments
0 Likes
Statistics
Notes
  • Be the first to comment

  • Be the first to like this

No Downloads
Views
Total Views
227
On Slideshare
0
From Embeds
0
Number of Embeds
0
Actions
Shares
0
Downloads
9
Comments
0
Likes
0
Embeds 0
No embeds

Report content
Flagged as inappropriate Flag as inappropriate
Flag as inappropriate

Select your reason for flagging this presentation as inappropriate.

Cancel
No notes for slide

Transcript

  • 1. BITS 2513 INTERNET TECHNOLOGY LECTURE 2: UNDERSTANDING NETWORKS 1
  • 2. • Network Terminology • Network Components • Operating Systems on the Network TOPICS Network • The OSI Model and Networking • Addressing on a Network • How Data Travels on the Network: an Example 2
  • 3. • Network Adapter – Usually an expansion card called NIC (Network Interface Card) • Network Protocol – A set of rules for network communications. Examples: Network Terminology • OS protocols: TCP/IP, NetBEUI • Hardware protocols: Ethernet, Token Ring • Segments, Packets, Datagrams – Small “chunks” of data that travel on network – In the network media, the packets travel in frames, which carry each data packet with a header and trailer to identify each packet 3
  • 4. Network Components 4
  • 5. • Hardware: – Network Interface Card (NIC) – Servers – Workstations • Software: – Operating Systems – Applications – Middleware Network Components – Workstations – Hub, MAU, Concentrator, Switch – Connectors (RJ-45, BNC) – Cable(UTP, coax) – UPS (Uninterruptable Power Supply) 5
  • 6. NIC Hub switch UPS MAU RJ-45 and UTP BNC male
  • 7. Operating Systems on the Networkthe Network 7
  • 8. Introduction • Communications between computers require network OS(es) and network protocols. • Functions of OS in a computer: – manage applications, hardware, and connection to the network. – enabling the computers on the local area 8 – enabling the computers on the local area network (LAN) to share their resources • Protocols specify network functionality. – Using the same set of network protocols, different devices can communicate. – The selected network protocol must be supported by every operating system on the network. – Example : HTTP, SMTP and FTP
  • 9. Introduction (continued) How resources are shared: ◦ peer-to-peer model: several computers using different operating systems in a small business or home can be connected to form a small LAN. ◦ client/server model, a.k.a. domain model, a server is used to control which resources on the LAN are shared, and who can access these resources. 9 Network OSes are used to manage resource sharing through mechanisms such as ◦ user account: a collection of all of the information that pertains to a user on a computer ◦ authentication, validation, or logging on: The process of entering a correct user ID and password to gain access to a computer
  • 10. • Windows 98 and Windows Me • Windows NT Workstation, Windows 2000 Professional, Windows XP • Linux • Macintosh OSes e.g. Mac OS X Client OSes • Macintosh OSes e.g. Mac OS X 10
  • 11. • can be installed on a server and used to manage network resources, including user accounts, printers, and file sharing across the LAN. • Windows NT Server, Windows NT Network OSes • Windows NT Server, Windows NT Enterprise Server • Windows 2000 • Windows Server 2003 • Novell NetWare • UNIX, Linux 11
  • 12. Network Operating Systems • Some criteria to consider when selecting a NOS are as follows: – Reliability – stably perform in any condition – Performance – serve the clients in a seamless way – Adaptability – adapt request of diff. platform 12 – Adaptability – adapt request of diff. platform – Security – ability to eliminate and repel threats – Scalability – cont. function well when size expand – Affordability – Ease of use and ease of installation
  • 13. The OSI Model and Networking 13
  • 14. Variety – OS: Apple OS X, Windows, Linux, Unix, Sun. Hardware: Cisco, 3Com,Huawei In an effort to identify and standardize all the levels of communication needed in networking, ISO developed a networking Understanding the OSI Model networking, ISO developed a networking model called the Open Systems Interconnection (OSI) reference model. The OSI reference model provides a universally accepted reference illustrating how data is transmitted on a network or between two or more networked devices. 14
  • 15. Understanding the OSI Model 15
  • 16. Understanding the OSI Model (Continued) Physical Layer Physical layer is responsible for: Passing data packets on to the cabling or wireless media (whether the media be cabling or wireless). Data is in ‘bit’ form 16 Data Link Layer Data Link layer is responsible for: Receiving packets of data from the Network layer and presenting them to the Physical layer for transport. E.g: NIC (with firmware) When software is permanently embedded on a hardware device, it is called firmware. Data is called ‘frame’
  • 17. Network Layer • Network layer is responsible for: Dividing a block of data into segments that are small enough to travel over a network. Understanding the OSI Model (Continued) travel over a network. • Segments of data are called packets, data packets, or datagrams and contain data, along with special identifying information in headers and trailers at the beginning and end of the packet. 17
  • 18. Transport Layer Transport layer is responsible for: Error checking and requests retransmission of data if it detects errors. The Transport layer might or might not guarantee successful delivery of data (depends on the transport protocol used). Understanding the OSI Model (Continued) protocol used). Data is called ‘segment’ Session Layer Session layer is responsible for: Establishing and maintaining a session between two networked stations or hosts. A host is any computer or other device on a network that has been assigned an IP address. 18
  • 19. Presentation Layer • Presentation layer is responsible for: receiving requests for files from the Application layer, and presents the requests to the Session layer. • The Presentation layer reformats, compresses, or encrypts data as necessary. Understanding the OSI Model (Continued) • The Presentation layer reformats, compresses, or encrypts data as necessary. Application Layer • The Application layer of the OSI model is responsible for interfacing with application software, such as Web browsers or Web servers. 19
  • 20. TCP/IP Protocols at Each Layer (Continued) 20
  • 21. The OSI Model Applied to a TCP/IP Network The Web browser wants to make a request to a Web server, and processes the request using an API (Application Program Interface )call to the OS. The API process packages the data using HTTP format, which includes an HTTP header, and addresses it to an IP address and port 80, which is the default port for a Web server. 21 Fig 5-33 An application asks the OS to do something using an API call
  • 22. The OSI Model Applied to a TCP/IP Network (Continued) • HTTP delivers the package to TCP, giving the destination IP address and port. 22
  • 23. The OSI Model Applied to a TCP/IP Network (Continued) • TCP hands the data off to IP, which resides in the network layer and is also managed by the OS. 23
  • 24. The OSI Model Applied to a TCP/IP Network (Continued) The data with its header information is a long stream of bytes. IP breaks it into individual packets. IP adds its own IP header that contains its own IP address (source) and the server’s IP address (destination). IP passes the packets off to the hardware (NIC).to the hardware (NIC). 24 Fig 5-36 IP divides data into packets, which are then released to the network
  • 25. The OSI Model Applied to a TCP/IP Network (Continued) On the NIC, each packet is given information at its beginning and end in the form of frame. A checksum is calculated using acalculated using a technique called cyclical redundancy check (CRC). Then each frame is sent off to the Ethernet cable. At the destination, the checksum is verified and passed to the IP layer to be regrouped. 25
  • 26. The OSI Model Applied to a TCP/IP Network (Continued) • IP then passes the reassembled data and header stream on to the TCP layer who acknowledges the TCP layer on the client. 26
  • 27. The OSI Model Applied to a TCP/IP Network (Continued) • The HTTP server, listening at port 80, receives the data and passes it on to the Web server. 27
  • 28. TCP/IP Protocols at Each Layer (Continued) 28
  • 29. • TCP/IP covers the first five layers of the OSI model, and is included in an operating system as a group of utilities called the TCP/IP stack. TCP/IP Protocols at Each Layer • Figure 5-41 shows the four major groupings of the OSI model as applied to TCP/IP networks. 29
  • 30. 30
  • 31. • The first three layers of the OSI model are handled by the protocol specific to the application using it and are best treated as a single group rather than Protocols at the Application, Presentation, and Session Layers treated as a single group rather than unique layers. • The language or protocol each of these applications uses is listed at the Application, Presentation, and Session layers. 31
  • 32. • A TCP/IP network has two protocols that work at the Transport layer; one protocol guarantees delivery and the other does not. • With TCP/IP, the protocol that guarantees delivery is TCP and the Protocols at the Transport Layer • With TCP/IP, the protocol that guarantees delivery is TCP and the protocol that does not is UDP (User Datagram Protocol). • TCP is used for client and server requests and responses. • UDP ?? 32
  • 33. • Because TCP establishes a connection, it is called a connection-oriented protocol. • UDP is a protocol that sends data Protocols at the Transport Layer (Continued) • UDP is a protocol that sends data without caring about whether the data is received. • It does not establish a connection first; thus, it is called a connectionless protocol. 33
  • 34. • TCP and UDP communicate with the Network layer, which is sometimes called the Internet layer. • Some of the other supporting protocols include ARP (Address Resolution Protocol), responsible for locating a host on a LAN; RARP (Reverse Address Protocols at the Network Layer locating a host on a LAN; RARP (Reverse Address Resolution Protocol), responsible for discovering the Internet address of a host on a LAN; and ICMP (Internet Control Message Protocol), responsible for communicating problems with transmission to devices that need to know about these problems. 35
  • 35. • PPP (Point-to-Point Protocol) is used over telephone lines, and allows a computer to connect to a network using a modem. • PPP is the most popular protocol for Protocols at the Data Link and Physical Layers • PPP is the most popular protocol for managing network transmission from one modem to another. 36
  • 36. Addressing on a Network 37
  • 37. • MAC addresses function at the lowest (Data Link) networking level. • If a host does not know the MAC address of another host on a local area network, it uses the operating system to discover the MAC (Media Access Control)Addresses uses the operating system to discover the MAC address. • MAC-48 addresses in human-friendly form is six groups of two hexadecimal digits • e.g. 01-23-45-67-89-ab or 01:23:45:67:89:ab 38
  • 38. • All the protocols of the TCP/IP suite identify a device on the Internet or an intranet by its IP address. • An IP address is 32 bits long, made up of 4 bytes separated by periods. • Within an IP address, each of the four IP Addresses • Within an IP address, each of the four numbers separated by periods is called an octet. • The first part of an IP address identifies the network, and the last part identifies the host. 39
  • 39. • IP addresses that can be used by companies and individuals are divided into three classes: Class A, Class B, and Class C, based on the number of possible IP addresses in each network within each class. Classes of IP Addresses class. • The group of IP addresses assigned to an organization are unique to all other IP addresses on the Internet and are available for use on the Internet. • The IP addresses available to the Internet are called public IP addresses. 40
  • 40. • Private IP addresses are IP addresses that are assigned by a network administrator for use on private intranets that are isolated from the Internet. • The RFC 1918 recommends that the Private IP Addresses • The RFC 1918 recommends that the following IP addresses be used for private networks: – 10.0.0.0 through 10.255.255.255 – 172.16.0.0 through 172.31.255.255 – 192.168.0.0 through 192. 168. 255.255 41
  • 41. • Instead of IP addresses permanently being assigned to computers (called static IP addresses), an IP address is assigned for the current session only Dynamically Assigned IP Addresses assigned for the current session only (called a dynamic IP address). • Internet service providers (ISPs) are organizations through which individuals and businesses connect to the Internet. 42
  • 42. • If the hosts on a network using private IP addresses need to access the Internet, a problem arises because the private IP addresses are not allowed on the Internet. Network Address Translation • The solution is to use NAT (Network Address Translation), which uses a single public IP address to access the Internet on behalf of all hosts on the network using other IP addresses. 43
  • 43. • Because of an impending shortage of IP addresses, as well as some limitations in the current standards for IP, a new scheme of IP addresses called the IPv6 (IP version 6) standard is currently being Plans for New IP Addresses (IP version 6) standard is currently being developed and implemented. • Current IP addresses using the current IPv4 (IP version 4) have 32 bits with eight bits in each of four octets. 45
  • 44. • With the new system, each address segment can have 32 bits, for a total of 128 bits for the entire address. • A disadvantage of IPv6 is the fact that so much software used on the Internet would Plans for New IP Addresses (Continued) much software used on the Internet would become outdated because current software is designed to hold 32-bit IP addresses and, with the new system, this number would no longer be sufficient. 46
  • 45. IPv6 Status April 2013 • IPv6 address allocation has happened and is happening very smoothly • More work in regional and local transit networkstransit networks • Content providers (especially local content) and enterprise customers need to keep working on enabling IPv6 in their Internet resources
  • 46. • A port is a number used to address software or services running on a computer. • A host computer might have several services running on it. Ports services running on it. • Each server running on the host is assigned a port. • The port is written at the end of the IP address, separated from the IP address with a colon—like this: 169.49.209.19:80 49

×