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Chapter 2 part 2

Chapter 2 part 2. Building a Network with OSI. OSI 7 Layer Model: Networking Hardware and Software. Sender. Receiver. Networking Software. Networking Hardware. OSI 7 Layer Model: Networking Hardware and Software. Layer 1. Physical Communication media, hub, NIC Layer 2. Data-link

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Chapter 2 part 2

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  1. Chapter 2 part 2 Building a Network with OSI

  2. OSI 7 Layer Model: Networking Hardware and Software Sender Receiver Networking Software Networking Hardware

  3. OSI 7 Layer Model: Networking Hardware and Software • Layer 1. Physical • Communication media, hub, NIC • Layer 2. Data-link • NIC, switch • Layer 3. Network • Router, network layer software • Layer 4. Transport • Transport layer software • Layer 5. Session • Session software • Layer 6. Presentation • Encryption/decryption program, compression/decompression program • Layer 7. Application • Network application software

  4. Physical Connection: Networking Hardware: Media (Physical layer device) • Communication media: • Media over which information is traveling

  5. Physical Connection: Networking Hardware : Media (Physical layer device) • Wire media: • Visible/touchable media • Wireless media: • Invisible/untouchable media

  6. Wire

  7. Physical Connection: Networking Hardware : Hub (Physical layer device) • Hub: • A central connection device • To connect three or more computers • Ports • Whenever a hub receives data from one port, it will forward the data to ALL other ports

  8. Hub Computer A Drop/destroy the message For Computer B Computer B Accept the message Drop/destroy the message Drop/destroy the message Drop/destroy the message

  9. Physical Connection: Networking Hardware : NIC (Physical and Data Link layer device) • NIC: • The interface between a computer and a network • Enabling the computer to send/receive information from/to the network

  10. Network Interface Card (NIC): Expansion board

  11. Network Interface Card (NIC ): Expansion board

  12. Another type of NIC: PCMCIA

  13. Another type of NIC: USB NIC

  14. Physical Connection: Networking Hardware : NIC (Physical and Data Link layer device) • NIC: • A unique identification number • MAC address (“physical address”) • 48 bits (48 binary digits/0s and 1s) or 12 hexadecimal characters • The first six hexadecimal characters: Organizationally Unique Identifier (OUI) = manufacturer ID (assigned by IEEE) • The last six hexadecimal characters: Device ID (assigned by the manufacturer)

  15. Physical Connection: Networking Hardware : NIC (Physical and Data Link layer device) • NIC: • NIC creates, sends, receives, reads, and destroys frames • Frame types depend on NIC types • Ethernet NIC: Ethernet frame • Token Ring NIC: Token Ring frame

  16. Physical Connection: Networking Hardware : NIC (Physical and Data Link layer device) • NIC: • A frame’s parts: • Recipient’s MAC address • Sender’s MAC address • Data • CRC (Cyclic Redundancy Check)

  17. Physical Connection: Networking Hardware : NIC (Physical and Data Link layer device) • CRC: • Function: • To detect error during transmission • How does CRC work? (Read Tech Tip on page 16)

  18. How Does NIC Work in Data Communication? The Network layer program (e.g., IP) sends information (packet) to NIC NIC creates a frame(encapsulation) NIC checks the communication medium to see if it is free and releases the frame to the communication medium if it is free (network access method) The frame goes to a hub The hub sends the frame to all other computers

  19. How Does NIC Work in Data Communication? • Every recipient’s NIC will compare the destination MAC address in the frame to its own MAC address. If they are the same, the NIC will process the frame. Otherwise, the NIC will delete (erase, destroy) the frame • Once the correct NIC receives the frame: • Decapsulation • CRC is used to detect transmission error • Packet is forwarded to the upper layer software

  20. How Does NIC Work in Data Communication? • By default, one network (one collision domain = a set of computers connected to a hub(s)) can only be used by one computer at any time • If there are two or more computers releasing frames to the network at the same time, there will be collision and the frames will have to be resent. • To avoid collision: • Network access method/Media access control: A mechanism that controls when a NIC must release a frame into the network (the timing of a frame release)

  21. Physical Connection: Networking Hardware : Switch (Data Link layer device) • Switch: • Another central wiring device • Unlike hub that simply broadcasts the information to all other computers in the network, switch forwards the information to the actual destination computer only • Switch uses physical address (MAC address) to identify the actual destination computer, hence, is considered to be a Data Link layer device

  22. Switch Computer A For Computer B Switch Computer B Accept the message

  23. Network layer program/software • Network layer software (e.g., IP) adds sender’s and receiver’s address (“logical address”)

  24. Logical Address Physical Address

  25. Network layer program/software • An example of network layer software: • IP software • The IP part in the TCP/IP software assigns logical address to a computer (IP address) • IP address: four 8 bit-numbers, or four groups of decimal numbers within the range of 0 to 255 separated by periods • IP address consists of: • Network addresses • Host address

  26. Network layer program/software • Why using two address systems: physical address and logical address? • The physical address is the original address for each computer (to identify each computer) • The logical address is added to allow the frame to be routed more efficiently by using the network address in the IP address (to locate a computer more easily) • The logical address is also added to allow the frame to be routed to a different network (another network that uses different physical address, see page 24)

  27. Network layer program/software • NIC (hardware) : frame containing physical addresses (e.g., MAC address), • Network layer protocol (software) : packet containing logical addresses (e.g., IP address) • Sometimes, frame, packet, block, datagram, segment are used interchangeably to refer to the same thing

  28. Router(Network layer device) • Router: • Another central connecting device • Having the routing capability provided by the Network layer software • Network layer device because it uses the logical address to route information to the destination • Allowing the information to go to a different network (using different physical address)

  29. ROUTER Computer A For Computer B Switch Computer B Accept the message

  30. Router Router Computer B Computer A For Computer B path A Router Router path B

  31. Hub, Switch, and Router

  32. Transport layer software • Transport layer software: • Segmentation/fragmentation • Example: TCP part of the TCP/IP • Why segmentation? • A frame has size limitations • When the information is larger than the max frame size, segmentation must be done

  33. Session layer software • Session layer software • Establishing and terminating communication session (connection) • Specifying the type of the communication session (connection): • Simplex, Half Duplex, Full Duplex • Managing multiple sessions (connections)

  34. Session layer software • What is an example of session software? • Read: http://books.google.com/books?id=Pm4RgYV2w4YC&pg=PA110&lpg=PA110&dq=TCP/IP+guide+session+layer+layer+5&source=bl&ots=qvjQlKGzcB&sig=IYYL7Q0Q6D7KWM1LaxqOjwhpv8I&hl=en&ei=XEiUSrXSI6KQtgeipKFP&sa=X&oi=book_result&ct=result&resnum=3#v=onepage&q=&f=false

  35. Encryption/description and compression/decompression program(Presentation layer software) • Presentation layer software: • Encryption/decryption program • Compression/decompression program • These programs are usually incorporated into the network application software

  36. Network application software (Application layer software) • Network application software: • Accepting and executing command from the user • Examples: • HTTP application software: Web server software (e.g., Apache, IIS), Web client software (e.g., Mozilla Firefox, Internet Explorer) • FTP application software: FTP client software (FileZilla FTP client software), FTP server software (FileZilla FTP server software)

  37. OSI 7 Layer Model in Youtube.com http://www.youtube.com/watch?v=W438koUR04o&feature=fvst

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