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Any Questions?. Chapter 4 – Introducing Protocols. Introducing Protocols. Unit objectives Discuss access protocols Discuss channel access methods Discuss transport protocols Discuss remote access protocols Discuss security protocols. Topic A. Topic A: Introduction to protocols

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  1. Any Questions?

  2. Chapter 4 – Introducing Protocols

  3. Introducing Protocols Unit objectives • Discuss access protocols • Discuss channel access methods • Discuss transport protocols • Discuss remote access protocols • Discuss security protocols

  4. Topic A • Topic A: Introduction to protocols • 1.2 Specify the main features of 802.2 (Logical Link Control), 802.3 (Ethernet), 802.5 (token ring), 802.11 (wireless), and FDDI (Fiber Distributed Data Interface) networking technologies, including: • Speed • Access method (CSMA / CA (Carrier Sense Multiple Access/Collision Avoidance) and CSMA/CD (Carrier Sense Multiple Access / Collision Detection)) • Topology • Media

  5. What is a protocol • A protocol defines the way in which two (or more) computers communicate. This includes definitions of the following items: • Identification of unique nodes (network stations) • Addressing • Routing between networks, if supported • Data format and packaging • Delivery sequencing • Error detection and recovery

  6. IEEE 802 series • The 802 series of specifications was named after the date when the IEEE Computer Society “Local Network Standards Committee,” Project 802, held their first meeting, which was in February (2) of 1980(80)

  7. IEEE 802 series • The 802 series of specifications define the physical media for each specification (802.3, 802.4, 802.5, and so on)

  8. Specification Media • 802.3 CSMA/CD (Ethernet) • 802.3z Gigabit Ethernet • 802.3ae 10 Gigabit Ethernet • 802.4 Token Bus • 802.5 Token Ring • 802.0 Executive Committee • 802.1 Higher Layer Interfaces • 802.2 Logical Link Control (LLC) • 802.6 Metropolitan Area Network (MAN) • 802.7 Broadband LAN • 802.8 Fiber Optic LAN • 802.9 Integrated Voice and Data LAN • 802.10 Standards for Interoperable LAN Security • 802.11 Wireless networks • 802.12 Demand Priority Access LAN, 100BaseVG-AnyLAN

  9. Protocol compatibility • A computer, by using one protocol, cannot communicate directly with a computer that uses a different protocol

  10. Access protocols • The Data Linklayer specifies how devices attached to the network can gain access to network resources

  11. Access protocols • The Institute of Electrical and Electronic Engineers (IEEE) modified the OSI reference model by breaking the data link layer into two additional layers • Media Access Control (MAC) layer • Logical Link Control (LLC) layer

  12. Any Questions?

  13. The Data Link layer - Modified

  14. Access protocolsKey Ideas • 802.2-LLC Layer • 802.3-Ethernet-CSMA/CD • 802.5-Token Ring-Token Passing • 802.11-Wireless-

  15. Any Questions?

  16. Topic B- Channel access methods • 1.2 Specify the main features of 802.2 (Logical Link Control), 802.3 (Ethernet), 802.5 (token ring), 802.11 (wireless), and FDDI (Fiber Distributed Data Interface) networking technologies, including: • Speed • Access method (CSMA / CA (Carrier Sense Multiple Access/Collision Avoidance) and CSMA/CD (Carrier Sense Multiple Access / Collision Detection)) • Topology • Media • 1.3 Specify the characteristics (For example: speed, length, topology, and cable type) of the following cable standards: • 10BASE-T and 10BASE-FL • 100BASE-TX and 100BASE-FX • 1000BASE-TX, 1000BASE-CX, 1000BASE-SX and 1000BASE-LX • 10GBASE-SR, 10GBASE-LR and 10GBASE-ER • 1.6 Identify the purposes, features and functions of the following network components: • WAPs (Wireless Access Point)

  17. Topic B- Channel access methods • 1.7 Specify the general characteristics (For example: carrier speed, frequency, transmission type and topology) of the following wireless technologies: • 802.11 (Frequency hopping spread spectrum) • 802.11x (Direct sequence spread spectrum) • Infrared • Bluetooth • 1.8 Identify factors which affect the range and speed of wireless service. For example: • Interference • Antenna type • Environmental factors • 2.3 Identify the OSI (Open Systems Interconnect) layers at which the following network components operate: • WAPs (Wireless Access Point) • 2.14 Identify the basic characteristics (For example: speed, capacity and media) of the following WAN (Wide Area Networks) technologies: • FDDI (Fiber Distributed Data Interface)

  18. Channel access methods • Determine the physical methodology by which data is sent across the transmitting media

  19. Introducing Ethernet • CSMA/CD networks are more popularly known as Ethernet networks • Ethernet and 802.3 areCSMA/CD specifications

  20. Introducing Ethernet • CSMA/CD • The most common implementation of contention access • Does not detect collisions as much as it attempts to avoid collisions

  21. CSMA/CD • Transmission failures can be caused by: • Bad cabling • Improper termination • Collisions • Improper cable length

  22. Data collisions

  23. Introducing Ethernet • CSMA/CA • Alert message notifies nodes of transmission • Alert is shorter, retransmit limited

  24. Any Questions?

  25. Ethernet topologies • Some Ethernet topologies • 10Base-T • 10Base-FL • 100Base-TX • 100Base-FX • 1000Base-TX • 1000Base-CX • 1000Base-SX • 1000Base-LX • 10Base-SR • 10Base-LR • 10Base-ER

  26. Introducing token passing/Token Ring • A token is passed among the nodes of the network • Whichever node is in possession of the token is permitted to transmit

  27. Token Ring and 802.5 • Features of Token Ring include • Logical ring usually wired as a physical star • Transfer rate of 4 to 16 Mbps • Unshielded twisted pair, shielded twisted pair, or fiber optic cable • Deterministic, it is possible to predict the passage of the token

  28. Token Passing • More predictable than CSMA/CD • There is only one active token on the ring at any time. • Tokens travel at thousands of miles per second (fiber optic). • A token (data frame) passes from system to system. • A system can attach data to a token when the token is free (empty). • Each system receives and regenerates the token.

  29. Token Ring Topologies • Hosts are connected to an Multistation access unit (MSAU or MAU) • Each MSAU can support up to 72 hosts

  30. Beaconing • The beacon frame is used to define a failure domain • The failure domain includes the station reporting the failure, its nearest active upstream neighbor (NAUN), and everything in between

  31. Failure domain

  32. FDDI • Uses a double fiber ring • The secondary ring is for redundancy • Runs at 100 Mbps • It is typically found as the backbone connecting buildings on a campus or wider area, as nodes can be over 60 miles apart

  33. Any Questions?

  34. ATM • Topology that can reach throughput of almost 10000 Mbps • Is more commonly implemented at 155 or 622 Mbps • Uses small packets, which are called cells • Equipment is expensive • Smaller organizations will probably go to the cheaper Gigabit Ethernet standard

  35. Wireless – 802.11 and 802.11x • IEEE 802.11 is a group of specifications for wireless networks • Among others, specifications include 802.11, 802.11a, 802.11b and 802.11g

  36. Wireless

  37. Wireless • 802.11x wireless networks consist of Wireless Access Points (WAPs) and wireless clients • WAPs operate at the Physical and Media Access Control (MAC) layer of the OSI model • WAPs can, on average, communicate with up to 30 clients within a 100 meter radius

  38. Frequency Hopping Spread Spectrum • Frequency Hopping Spread Spectrum (FHSS) uses a wide range of frequencies in the 2.4 Ghz band • Data is transmitted on a single frequency at any given time, however, the signal hops from frequency to frequency in a pseudorandom pattern • This transmission technology can be used by 802.11

  39. Direct Sequence Spread Spectrum • Direct Sequence Spread Spectrum (DSSS) also operates in the 2.4 Ghz band • It employs a mechanism whereby the data being transmitted is spread over multiple frequencies, allowing for higher throughput rates • DSSS is used by the 802.11b and 802.11g standards

  40. Orthogonal frequency division multiplexing • With Orthogonal Frequency Division Multiplexing, the radio signal is split into multiple, smaller signals • These signals are transmitted at the same time, but at different frequencies • OFDM operates in the 5 Ghz band, which makes it more resistant to interference than FHSS and DSSS • OFDM is used by the 802.11a standard

  41. Interference • Both FHSS and DSSS are fairly resistant to interference from other nearby transmissions. • interference can come from other devices using the 2.4 Ghz band, such as microwave ovens and cordless phones.

  42. Any Questions?

  43. Antennas • Omnidirectional • Vertical Antenna • Directional • Yagi

  44. Bluetooth • Bluetooth’s aim is to allow the creation of small, short range, wireless networks, usually within a single room • It has a range of 10 meters, speeds of up to 1 Mbps and uses FHSS • Bluetooth and 802.11x devices cannot communicate with one another

  45. Infrared • Smaller distances • 1 meter • Good Speed • 115 Kbits to 4 Mbps

  46. Any Questions?

  47. Topic C: Transport protocols 1.2 Specify the main features of 802.2 (Logical Link Control), 802.3 (Ethernet), 802.5 (token ring),802.11 (wireless), and FDDI (Fiber Distributed Data Interface) networking technologies,including: . Speed . Access method (CSMA / CA (Carrier Sense Multiple Access/Collision Avoidance) and CSMA / CD (Carrier Sense Multiple Access / Collision Detection)) . Topology . Media 1.6 Identify the purposes, features and functions of the following network components: . Gateways 2.4 Differentiate between the following network protocols in terms of routing, addressing schemes, interoperability and naming conventions: . IPX / SPX (Internetwork Packet Exchange / Sequence Packet Exchange) . NetBEUI (Network Basic Input / Output System Extended User Interface) . AppleTalk / AppleTalk over IP (Internet Protocol) . TCP / IP (Transmission Control Protocol / Internet Protocol) 2.10 Define the purpose, function and use of the following protocols used in the TCP / IP (Transmission Control Protocol / Internet Protocol) suite: . TCP (Transmission Control Protocol) . UDP (User Datagram Protocol) 2.13 Identify the purpose of network services and protocols (For example: . SMB (Server Message Block) . AFP (Apple File Protocol)

  48. Connectionless protocols • Used when sending small packets of data, usually less than 1 KB • Packets are infrequently dropped • No need for the increased overhead of acknowledging each receipt

  49. Connection-oriented protocols • Used to send a large amount of information that is divided into multiple packets for transmission • Uses packet sequence numbers to verify packet order and acknowledges the receipt of each packet • The lost or improperly delivered packets, which are not acknowledged as a successful receipt, can be retransmitted

  50. Transport protocols • Transport protocols manage network communications and determine how data should be presented to the next layer • The protocols responsible for transporting data • NetBEUI • IPX/SPX • TCP/IP • AppleTalk

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