Networking Concepts Lesson 12 - WANs - Eric Vanderburg

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Networking Concepts Lesson 12 - WANs - Eric Vanderburg

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Networking Concepts Lesson 12 - WANs - Eric Vanderburg

  1. 1. Chapter 12 Wide Area Networks Networking Concepts – Eric Vanderburg ©2005
  2. 2. WANs  WANs look just like LANs to the end user except accessing them is slower.  WAN communication links:  Packet-switching networks  Fiber-optic cable  Microwave transmitters  Satellite links  Cable television coax systems Networking Concepts – Eric Vanderburg ©2005
  3. 3. Considerations  Speed  CIR (Committed Information Rate) – The minimum guaranteed transmission rate  Reliability  Cost  Availability Networking Concepts – Eric Vanderburg ©2005
  4. 4. WAN Technologies  Analog  Digital  Packet Switching Networking Concepts – Eric Vanderburg ©2005
  5. 5. Analog PSTN (Public Switched Telephone Network) & POTS (Plain Old Telephone System) – circuit switched – worse connection over longer distance PSTN Line Types:   1. 2. 3. 4. 5. 6. 7. 8. 9. 10. Voice Only Voice with minimal quality control Voice and radio with tone conditioning Less than 1200bps data applications Basic data Voice and data over trunk circuits Voice and data over private lines Voice and data over trunks between computers Voice and video Application relays, quality data Networking Concepts – Eric Vanderburg ©2005
  6. 6. Analog (continued)  Lease analog circuit to improve quality and speed. No dial on demand lag  Line conditioning – involves testing and line upgrades to maintain a quality standard  consistent transmission rate, improved signal quality, & reduced interference and noise  C1 - C8 & D Networking Concepts – Eric Vanderburg ©2005
  7. 7. Analyzing analog needs  How often do you need the connection? – always on, sometimes…  Bandwidth  Availability  Best for intermittent connections Networking Concepts – Eric Vanderburg ©2005
  8. 8. Digital Connectivity  DDS (Digital Data Service) – All digital WAN solutions       Synchronous dedicated point to point circuits with few errors 2.4, 4.8, 9.6, or 56 Kbps with nearly 99% error-free transmission ISDN T-Carrier (also E & J) *see handout* 64k per channel Switched 56k CSU/DSU (Channel Service Unit/Data Service Unit) – WAN communication device for digital connections – hands data off to bridge or router Networking Concepts – Eric Vanderburg ©2005
  9. 9. T Carrier  Multiplexing (muxing) - Combining server communication streams into one.  DS specifications DS-0 – 1 channel, 64kbps  DS-1 – T1, 24 channels, 1.544Mbps  DS-1c – 2 T1’s, 3.152Mbps  DS-2 – T2 (4 T1’s), 6.312Mbps  DS-3 – T3 (28 T1’s), 44.736Mbps, fractional T3 lines go in 6 Mbps sets  DS-4 – T4 (168 T1’s), 274.76Mbps, requires fiber  Networking Concepts – Eric Vanderburg ©2005
  10. 10. Other Digital technologies  Switched 56k       Charged per minute Dial on demand Faster because it is digital when analog did not support 56k ISDN B-ISDN (Broadband ISDN) – Data transfers over fiber and works with ATM, SONET & Frame Relay to give between 64k & 100Mbps Packet Switching (Internet) – data is broken into packets and then sequenced and sent to the destination on the best path Networking Concepts – Eric Vanderburg ©2005
  11. 11. Virtual Circuits  Virtual Circuits – logical dedicated pathways between points (created during the negotiation stage – Session layer)  SVC (Switched Virtual Circuit) – set up and taken down as needed (on demand)  PVC (Permanent Virtual Circuit) – created and maintained indefinitely Networking Concepts – Eric Vanderburg ©2005
  12. 12. X.25  SVC connection, originally used for mainframe to terminal connections  64kbps-2Mbps  Equipment  X.25 NIC  PAD (Packet Assembler/Disassembler)  LAN/WAN X.25 Gateway Networking Concepts – Eric Vanderburg ©2005
  13. 13. Frame Relay  Uses PVC’s  No error checking  Faster performance  Variable length frames  Less expensive carrier type compared to ATM, T1  Layer 2 technology  Purchased in 64k increments  Requires CSU/DSU Networking Concepts – Eric Vanderburg ©2005
  14. 14. ATM     Can be used for voice, data, & fax Can use SVC or PVC Layer 2 Transport steps       Header (first 5 bytes) is read to virtual circuit Virtual circuit is used to as the pathway Receiving node gets the cell and analyzes the header to see who it is for Versatile like Ethernet is Max bandwidth is 2.4Gbps ATM central connecting devices are all called switches that operate like:   Hubs to forward data from one computer to another within a network. Router-like devices to forward data at high speeds to remote networks. Networking Concepts – Eric Vanderburg ©2005
  15. 15. Others  FDDI  SONET  SMDS (Switched Multimegabit Data Service) – 1.544Mbps – 45Mbps Uses cells (53bytes)  No error checking  802.6 MAN standard along with billing services  uses the DQDB (Distributed Queue Dual Bus) as the interface and access method for the network. SMDS is a dual-bus topology that forms a ring that is not closed  Networking Concepts – Eric Vanderburg ©2005
  16. 16. Equipment  CPE (Customer Premises Equipment) – The equipment located at the customer site. Ex: routers, modems, CSU/DSU  Demarcation Point – the spot where the CPE ends and the ISP’s responsibility begins  Local Loop/Last Mile – The cabling between the demarcation point and the CO (Central Office) or POP (Point of Presence) Networking Concepts – Eric Vanderburg ©2005
  17. 17. Equipment  DCE (Data Circuit-Terminating Equipment/Data Communications Equipment) – sends and receives data from the local loop/last mile.  DTE (Data Terminal Equipment) – The device that sends data from the customer network to the DCE  Router or Bridge Networking Concepts – Eric Vanderburg ©2005
  18. 18. Wiring Closets  MDF (Main distribution facility) – Central wiring closet when more than one is used  IDF (Intermediate distribution facility) – wiring closets off the MDF Networking Concepts – Eric Vanderburg ©2005

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