1. Thought For The Week No Question Is A Bad Question!

2. WAN Physical Layer Protocols Vary Widely In Speed And Cost. Key Point

3. At The End Of Lesson 2, You Should Be Able To: Name The Low- And High-Speed Options For Physical Layer MAN/WAN Connectivity Determine Which Technology Is Most Appropriate For A Given Business Application This Lesson Summarizes the Most Popular Physical Layer Protocols That Exist for Providing Connectivity to Wide Area Network (WAN) and Metropolitan Area Network (MAN) Networking Environments.

4. Point-To-Point Links Establish A Physical Connection Between Local And Remote Stations. A Point-To-Point Link Provides Dedicated Bandwidth For The Life Of The Circuit. Point-To-Point Links

5. LECs Offer Traditional Telecommunications Services That Use Existing Telephone Company Voice Network Facilities And The Copper Local Loop Between A Customer And Central Office (CO). Analog Lines

6. The Building Block For Digital Services Is The Digital Signal Level 0 (DS0). Basics Of Digital Data Speeds DS0 64 Kbps In Every Country In The World, The DS0, 64 Kbps, Is Recognized As The Basic Data Rate For Digital Data Transmission.

7. The Most Prevalent Method Of Converting Analog Signals To Digital Signals Is The Process Of Pulse Code Modulation (PCM). Analog-To-Digital Data Conversion DS0 64 Kbps In Every Country In The World, The DS0, 64 Kbps, Is Recognized As The Basic Data Rate For Digital Data Transmission. Building Block

8. Dataphone Digital Service (DDS) Is Also Called Digital Data Service. Connections Are Made To DDS Using A Special Box Called A Data Service Unit/ Channel Service Unit (DSU/CSU). Switched-56 (SW56) Service, Enables Dial- Up Digital Connections To Any Other SW56 Subscriber in the Country. Digital Data Service (DDS)

9. Switched-56 (SW56) Service, Enables Dial- Up Digital Connections to Any Other SW56 Subscriber in the Country. Switched-56 (SW56)

10. At The Top Of The Point-To-point Ladder Are The Truly High-Speed Digital Services, Including: Fractional T1 (FT1) T1 (24 DS0 Channels, 1.544 Mbps) T3 (672 DS0 Channels; 44.736 Mbps) Sonet (Basic Building Block Is STS-1, Or OC-1 – 51.84 Mbps; Ref. Table on Page 298) High-Speed Services

11. The Physical Layer Technologies Table Presents Key Physical Layer Technologies Most Often Used For Connection To A WAN. Various Data Rates And Associated Applications TechnologyData RatePhysical MediaApplication Dial-up DDS Leased Line Switched-56 14.4-56 Kbps 56 Kbps Low-Grade Twisted Pair Home Office Connectivity to Office and Internet Small Business Low-Speed Access Office-to-Office Connectivity Internet Connectivity Small Business Low-Speed Access Office-to-Office Connectivity Internet Connectivity Link Backup

12. Various Data Rates And Associated Applications TechnologyData RatePhysical MediaApplication Fractional T1 Satellite (Direct PC) T1 64 to 768 Kbps Low-Grade Twisted Pair Airwaves Small to Medium Business Moderate-level Speed Internet Access Small Business with Moderate-level Speed Internet Access Medium Business Internet Access Point-to-Point LAN Connectivity 400 Kbps downstream 33.6 Kbps upstream 64 Kbps to 1.544 Mbps Low-Grade Twisted Pair Optical Fiber Microwave

13. Various Data Rates And Associated Applications TechnologyData RatePhysical MediaApplication E1 ADSL Cable Modem 64 Kbps to 2,048 Mbps Low-Grade Twisted Pair Optical Fiber Medium Business Internet Access Point-to -Point LAN Connectivity Medium Business High-Speed Home Internet Access Low-Grade Twisted Pair 512 Kbps to 52 Mbps Coaxial Cable Low-Grade Twisted Pair

14. Various Data Rates And Associated Applications TechnologyData RatePhysical MediaApplication E3 T3 OC-1 34.368 Mbps Twisted Pair Fiber Optical Microwave Large Business Internet Access ISP Backbone Access Backbone, Campus Internet ISP 45 Mbps 51.48 MbpsFiber Optical Cable Twisted Pair Fiber Optical Microwave

15. Various Data Rates And Associated Applications TechnologyData RatePhysical MediaApplication E3 T3 OC-1 34.368 Mbps Twisted Pair Fiber Optical Microwave Large Business Internet Access ISP Backbone Access Backbone, Campus Internet ISP 45 Mbps 51.48 MbpsFiber Optical Cable Twisted Pair Fiber Optical Microwave

16. T1 System A T-1 Contains 24 64-Kbps Channels 24 x 64 Kbps = 1,536 Kbps A T-1 Has a Data Rate of 1,544 Kbps (1.544 Mbps) Why Is There An 8,000 bps Difference Between What We Believe That The T-1 Data Rate Is And The Actual Data Rate Of 24, 64 Kbps Channels?

17. T1 System - Continued 8 b/Channel/Frame X 24 Channels = 192 bits. Thus The Output bit rate is 193 X 8,000 = 1.544 Mbps. F Octet 1 Channel 1 Octet 2 Channel 2... Octet 24 F... 5.18  sec 125  sec 193 bit Framing bit

18. Bandwidth Is The Difference Between The Highest And Lowest Frequencies That Can Be Transmitted Across A Transmission Line Or Through A Network. Bandwidth Is Measured In Hertz (Hz) For Analog Networks. Bandwidth – Analog Transmission

19. Bandwidth Is Measured In Bits Per Second (bps) For Digital Networks. Bandwidth –Digital Transmission

20. Different Types Of Applications Require Different Bandwidths For Effective Use. Application Bandwidth ApplicationRequired Bandwidth PC Communications300 bps T0 56 Kbps Digital Audio128 Kbps To 1 Megabit/sec Compressed Video128 Kbps To 2 Mbps Document Imaging10 To 100 Mbps Full-Motion Video250 Kbps To 2 Gbps

21. The Greater The Range Of Frequencies A Medium Can Handle, The Greater Its Information-Carrying Capacity. Bandwidth

22. Multiplexers and Subscriber Lines 24 DS-0 CSU Network Interface Repeater 3000 Ft Repeater Frame Office Repeater Bay ~ 6,000 Ft In Loop Central Office 3000 Ft Mux T1

23. Traffic Carried By T1 System Digital Voice At 64, 32, or 16 Kbps on DS-1 Channels Digital Data At 56 Kbps, or Multiples Of 64 Kbps Subrate Data At 2.4 4.8, 9.6, Or 19.2 Kbps On DS-1 Channels

24. Traffic Carried By T1 System To Accommodate These Signals On DS-1 Lines Requires A Range O Multiplexers. Some Of Them Are: M24: Original T-1 System M44: 44 Voice Channels That Are Converted To 44, 32-Kbps Voice Channels. They Occupy 22 DS-0 Channels. The Remaining 2 DS-0s Are Used For Common Channel Signaling.

25. Traffic Carried By T1 System Continued: M48: 48 Voice Channels That Are Converted To 48, M88: 88 Voice Channels That Are Converted To 88, 16-Kbps Voice Channels. They Occupy 22 DS-0 Channels. The Remaining 2 DS-0s Are Used For Common Channel Signaling.