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Ethernet Tutorial

Ethernet Tutorial. Introduction. LANS. Networks usually confined to a small geographic area single building college campus The proliferation of LANs worldwide business education. Protocols. Standards that allow computers to communicate. Defines identify one another on a network

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Ethernet Tutorial

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  1. Ethernet Tutorial

  2. Introduction

  3. LANS • Networks usually confined to a small geographic area • single building • college campus • The proliferation of LANs worldwide • business • education

  4. Protocols • Standards that allow computers to communicate. • Defines • identify one another on a network • the form that the data should take in transit • how this information should be processed once it reaches its final destination

  5. Protocols (continued) • Defines (continued) • procedures for handing lost or damaged transmissions or “packets” • Examples • IPX • TCP/IP • DECnet • AppleTalk • LAT

  6. Protocols (continued) • Protocol independence • the physical network doesn’t need to concern itself with the protocols being carried • allows multiple protocols to peacefully coexist • allows the builder of a network to use common hardware for a variety of protocols

  7. What is Ethernet?

  8. Ethernet • The most popular LAN technology • a good balance between speed, price and ease of installation • The perfect networking technology for most computer users today • wide acceptance into the computer marketplace • the ability to support virtually all popular network protocols

  9. Ethernet (continued) • Defined by the Institute for Electrical and Electronic Engineers (IEEE) • IEEE Standard 802.3 • configuring an Ethernet • specifying how elements in a network interact with one another

  10. Media and Topologies

  11. Topologies • define how “nodes” are connected to one another • a node is an active device connected to the network • computer • repeater • bridge • router

  12. Topologies(continued) • Ethernet media are used in two general configurations or topologies • Bus • Star

  13. Bus topology • consists of nodes strung together in series with each node connected to a log cable or bus • a break will usually cause the entire segment to be inoperable

  14. Star topology • links exactly two nodes together • a break will only affect the two nodes on that link

  15. Media • Major types of media in use today • ThickWire • Thin coax • Unshielded twisted pair • Fiber optic

  16. ThickWire • 10 BASE5 Ethernet • used for “backbones” • up to 500m long • as many as 100 nodes • use “vampire tap” to connect new nodes • nodes must be spaced exactly in increments of 2.5m

  17. Thin Coax • 10BASE2 Ethernet • lower cost and easier installation • up to 185m long • as many as 30 nodes • each at least 0.5m apart • connected or disconnected at the “T” connectors

  18. Twisted Pair • Level 5: 100Mbps • Level 4: 20Mbps • Level 3: 16Mbps • Level 2 and 1: less than 5Mbps • 10BASE-T Ethernet • uses a star topology • up to 100m long

  19. Fiber Optic • 10BASE-FL Ethernet • useful against situations of electro-magnetic interference, lightning strike and so on • up to 2km long • can use for FDDI and other technologies faster than Ethernet

  20. Transceivers

  21. Transceivers • used to connect nodes to the various Ethernet media • known as Media Attachment Units (MAU)

  22. Transceivers (continued) • provide an Application User Interface (AUI), connector for the computer • many interface network cards also contain a buit-in 10BASE-T or 10BASE2 transceiver

  23. Examples of Transceiver • LTX-T (Twisted Pair Transceiver) • LTX-TA (Twisted Pair Mini Transceiver) • LTX-2 (Thin Coax Transceiver) • LTX-2A (Thin Coax Mini Transceiver) • LTX-5 (ThickWire Transceiver) • LTX-FL (Fiber Optic Transceiver)

  24. Repeaters

  25. Repeaters • connect two or more Ethernet segments of any media type • provide the signal amplification • Splitting a segment into two or more with a repeater allows a network to grow

  26. Repeaters (continued) • count in the total node limit • e.g. . a Thin Coax segment • 185m long • 29 nodes and a repeater • e.g. . a ThickWire segment • 500m long • 98 nodes and 2 repeaters

  27. Repeaters (continued) • necessary in star topologies • one end the repeater • the other the computer w/ a transceiver • monitor Ethernet to run correctly • e.g. . when a break occurs • limit the effect of inoperable problems by “segmenting”, disconnecting the problem segment

  28. Repeaters (continued) • The IEEE 802.3 specifications • describe rules for the maximum number of repeaters in a configuration • e.g. . the transmission path between two nodes the maximum number of network segments between two nodes 4 5

  29. Bridges

  30. Bridges • Function: To connect separate Ethernet together • Goal: To achieve what appears to the network users to be a seamless network

  31. Bridges (continued) • map the Ethernet addresses of the nodes residing on each network segment • then, allow only the necessary traffic to pass through the bridge

  32. Bridges (continued) • When a packet is received by the bridge: • the bridge determines the destination and source segments • If the segments are the same • the packet is dropped (“filtered”) • If the segments are different • the packet is “forwarded” on

  33. Bridges (continued) • prevent all bad or misaligned packets form spreading from one segment to the others • called “store-and-forward” devices • look at the whole Ethernet packet before making their filtering or forwarding decisions

  34. Ethernet Switches

  35. Ethernet Switches • “Cut-through” switches • examining the address information contained at the start of the Ethernet packet • decrease the amount of time required to determine if a packet should be filtered or forwarded, “latency”

  36. Ethernet Switches(continued) • The term “Ethernet Switch” • any device of multiple ports which is able to filter and forward packets at nearly the speed of Ethernet (“wirespeed”) regardless of the technique • because store-and-forward bridges have now increased their speed

  37. Ethernet Switches(continued) • The term “Bridge” • two-port devices which use the store and forward technique

  38. Routers

  39. Routers • filter out network traffic • filter by specific protocol • born out of the necessity for dividing networks logically instead of physically

  40. Routers (continued) • An IP router • divide a network into various subnets • only traffic destined for particular IP addresses can pass between segments • takes more time than a switch or bridge which only looks at the MAC layer

  41. Routers (continued) • The term “brouters” • devices which have both bridging and routing capability • however switches and bridges frequently have some router-like features such as selective protocol filtering

  42. Network Switch Example LTX-5 LTX-5 LTX-5 LTX-5 LTX-5 LTX-5 LSB4 Switch Netware File Server (C) Microvax (B) Macintosh (D) PC (A) LTX-2 LTX-2 LTX-2 LTX-2 LTX-2 LTX-2 Microvax (F) Sun (G) Sun (H) Workstation (E)

  43. The Spanning Tree

  44. The Spanning Tree • The Spanning Tree Algorithm • a software device for describing how switches & bridges can communicate to avoid network loops • By exchanging packets called BPDUs, the switches & bridges establish a singular path for reaching each network segment.

  45. The Spanning Tree(continued) • A switches or bridge port is turned off • if another pathway to that segment already exists

  46. The Spanning Tree(continued) • The process of passing the BPDU packets is continuous • so if a switch or bridge suddenly fails, • then the remaining devices will reconfigure pathways to allow each segment to be reached

  47. The Spanning Tree(continued) • network managers design loops into a bridged network • so if a switch or bridge does fail, • the Spanning Tree will calculate the alternate route into the network configuration.

  48. Spanning Tree Example LTX-5 LTX-5 10BASE5 LTX-2 10BASE2 AUI CABLE AUI CABLE LTX-2 LB2 #1 LB2 #4 LB2 #3 AUI CABLE LTX-5 10BASE5 10BASE2 LTX-2 LTX-5 LTX-2 AUI CABLE LB2 #2

  49. Terminal & Printer Servers

  50. Terminal & Printer Servers • support the use of following on networks • terminals • printers • modems, and • other serial devices • have own network addresses • perform more than just a physical connection or signalforwarding function

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