1 / 28

Introduction

Introduction. Channels. INFORMATION IS MOVED FROM Tx & Rx THE SPEED AT WHICH THE INFORMATION IS MOVED BETWEEN Tx & Rx IS SET BY ITS “BIT RATE” ON THE CHANNEL. TRANSMITTER RECEIVER. Tx Rx CHANNEL. Channels II.

fergus
Download Presentation

Introduction

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Introduction

  2. Channels • INFORMATION IS MOVED FROM Tx & Rx • THE SPEED AT WHICH THE INFORMATION IS MOVED BETWEEN Tx & Rx IS SET BY ITS “BIT RATE” ON THE CHANNEL TRANSMITTER RECEIVER Tx Rx CHANNEL

  3. Channels II • CHANNELS ARE PHYSICAL AND CAN EITHER BE (BUT NOT LIMITED TO) • COPPER • FIBRE • WIRELESS • ALSO KNOWN AS THE “TRANSMISSION MEDIUM”

  4. Bit Rate 1 • 1,000 bit/s = 1 kbit/s (one kilobit or one thousand bits per second) • 1,000,000 bit/s = 1 Mbit/s (one megabit or one million bits per second) • 1,000,000,000 bit/s = 1 Gbit/s (one gigabit or one billion bits per second)

  5. Bit Rate 2 • SECTION OF TEXT: “THIS IS A TEST ” • TEXT CONTAINS 14 CHARACTERS • ASSUME 8 BITS PER CHARACTER • TOTAL 112 BITS OF INFORMATION COMPARISON OF BIT RATE AND TRANSMISSION TIME

  6. Bit Rate 3 • IMAGE FROM NASA: SURFACE OF MARS • PICTURE CONTAINS 1080 x 602 PIXELS, AT 8 BITS PER PIXEL THERE IS 5.2 Mbits OF INFORMATION IN THE PICTURE COMPARISON OF BIT RATE AND TRANSMISSION TIME

  7. Bit Rate 4 • Audio (MP3) • 32 kbit/s — MW (AM) quality • 96 kbit/s — FM quality • 128–160 kbit/s — Standard Bitrate quality; difference can sometimes be obvious (e.g. bass quality) • 192 kbit/s — DAB (Digital Audio Broadcasting) quality. Quickly becoming the new 'standard' bitrate for MP3 music; difference can be heard by few people. • 224–320 kbit/s — Near CD Quality. Sound is near indistinguishable from most CDs. • Other audio • 800 bit/s — minimum necessary for recognizable speech (using special-purpose FS-1015 speech codecs) • 8 kbit/s — telephone quality (using speech codecs) • 500 kbit/s–1 Mbit/s — lossless audio as used in formats such as FLAC, WavPack or Monkey's Audio • 1411 kbit/s — PCM sound format of Compact Disc Digital Audio

  8. Bit Rate 5 • Video (MPEG2) • 16 kbit/s — videophone quality (minimum necessary for a consumer-acceptable "talking head" picture) • 128 – 384 kbit/s — business-oriented videoconferencing system quality • 1 Mbit/s — VHS quality • 5 Mbit/s — DVD quality • 15 Mbit/s — HDTV quality • 36 Mbit/s — HD DVD quality • 54 Mbit/s — Blu-ray Disc quality

  9. Bandwidth • THERE ARE LIMITS ON BIT RATE • ALL CHANNELS HAVE AN UPPER LIMIT ON BIT RATE • THE LIMIT IS SET BY THE SO CALLED CHANNEL BANDWIDTH • BANDWIDTH IS MEASURED IN MHz & GHz • MEGAHERTZ & GIGAHERTZ (MILLIONS & BILLIONS OF HERTZ) • IN GENERAL THE LARGER THE BANDWIDTH THE GREATER THE INFORMATION CARRYING CAPACITY IN Bits/sec

  10. What is a Network? • A NETWORK CONSISTS OF A COLLECTION OF NODES AND CHANNELS • A NODE CAN CAN BE ANY NUMBER OF THINGS, FOR EXAMPLE • COMPUTER • PRINTER • SCANNER • BACKUP DRIVE • SECURITY CAMERA • SENSORS

  11. What is Topology? • TOPOLOGY DETERMINES THE WAY IN WHICH NODES AND CHANNELS ARE INTERCONNECTED • AN ANALOGY WOULD BE THAT OF A RAIL NETWORK • STATIONS (NODES) ARE CONNECTED TOGETHER BY RAIL TRACK (CHANNEL)

  12. Network Topologies Point to Point

  13. Network Topologies Bus

  14. Network Topologies Ring

  15. HUB Network Topologies Star

  16. Network Topologies • PHYSICAL STAR • RING CONFIGURATION • STAR TOPOLOGY

  17. Network Topologies • COLLAPSED BACKBONE • SIMILAR TO STAR

  18. Network Topologies Shared Bandwidth network

  19. Network Topologies Switched Bandwidth network

  20. Network Topologies

  21. ETHERNET

  22. Ethernet • Ethernet is the most popular LAN standard in the world with over 1 Billion installed nodes (1Billion nodes -IET Computing & Control Engineering | February/March 2007) • The original Ethernet came out around 1979 at 10 Mbps, and that’s where it stayed for more than 10 years • Ethernet runs over co-axial cable or twisted pair copper wires and provides a 10 Mbps to share between all users

  23. To Slow • Users were finding the 10 Mbps performance of Ethernet too slow. This bandwidth crunch is the result of three technological changes: • the increased speed of computer processors • the increased number of users on networks • new bandwidth-intensive applications on networks

  24. Ethernet Types • ETHERNET • 2/5 BASE T 10Mbps • THIN/THICK COAX ETHERNET • 10 BASE T 10Mbps • ORIGINAL TWISTED PAIR ETHERNET • 100 BASE T 100Mbps • FAST ETHERNET • 1000 BASE T 1000Mbps • GIGABIT ETHERNET

  25. Ethernet History • 802.3 1985 • 10Mbps THICK & THIN ETHERNET • 802.3u 1995 • 100Mbps FAST ETHERNET • 802.3z 1998 • 1000Mbps GIGABIT ETHERNET (FIBRE) • 802.3ab 1999 • 1000Mbps GIGABIT ETHERNET (COPPER)

  26. Ethernet • PROTOCOL • CSMA/CD • PHYSICAL MEDIUM • COAX • TWISTED PAIR • MULTIMODE FIBRE • SINGLEMODE FIBRE

  27. CSMA/CD START TRANSMITTING CARRIER SENSE MULTIPLE ACCESS WITH COLLISION DETECT LISTEN FOR COLLISION BACK OF FOR RANDOM PERIOD COLLISION YES NO CONTINUE TRANSMITTING

  28. Ethernet Over Copper • THIN/THICK COAX • OBSOLETE 2/5BASET • CAT 3 • OLD INSTALLATIONS 10BASET • CAT 4 • CAT5 MADE CAT4 OBSOLETE • CAT 5 • IN MAJORITY OF INSTALLATIONS

More Related