Fiber Optic Computer Network Overview

Transcription

1 Introduction to networking Copying and processing permitted for noncommercial purposes, on condition that proper reference to the source is given. Sergiusz Patela, 2001

2 Bandwidth comparison of networking media Wire pair Attenuation [db/km] Coaxial cable Microwave waveguides Multi mode optical fiber Single mode optical fiber MHz 1 GHz 1 THz Bandwidth (c) Sergiusz Patela Fiber-optic computer networks 2/26

3 Two basic network types Local Area Network - LANs connect computers and peripheral devices in a limited physical area, such as a business office, laboratory, or college campus, by means of permanent links (wires, cables, fiber optics, radio) that transmit data rapidly Wide Area Networks (long haul networks) - Wide-area networks connect computers and smaller networks to larger networks over greater geographic areas, including different continents. They link the computers by means of cables, optical fibers, or satellites. (c) Sergiusz Patela Fiber-optic computer networks 3/26

4 Contemporary LAN technologies - examples 1. Ethernet (802.3) Coax: 10Base T - 180m Fiber 10Base FL - 2 km 2. Token Ring (802.5) 802.5j - TR over fiber 3. FDDI (Ansi X3T12, ISO-IEC 9314) 4. Fibre Channel,... (c) Sergiusz Patela Fiber-optic computer networks 4/26

5 Computer network - a definition In plain English: system of several computers which are connected to one another by cables A network of data processing nodes that are interconnected for the purpose of data communication General non-computer-based example: Communications network - roads, bus stations, buses, containers, actual load (c) Sergiusz Patela Fiber-optic computer networks 5/26

6 Operating principles and fundamental terms Fundamental terms: layer and protocol Other terms: frame, access method, coding Protocol: set of rules describing how to prepare data for sending, establish communication, control data transfer etc. Protocols are standardized. Protocol description - according to OSI (Open System Interconnection) model have layered structure. For computers connected by the network layers of given level communicate between themselves, transferring data only to the layer immediately above and beneath them. (c) Sergiusz Patela Fiber-optic computer networks 6/26

7 The OSI -ISO Network Model (Open Systems Interconnection) Device 1 Device 2 7 Application <---> 7 Application 6 Presentation <---> 6 Presentation program 5 Session <---> 5 Session 4 Transport <---> 4 Transport 3 Network <---> 3 Network 2 Data Link <---> 2 Data Link hardware 1 Physical layer <---> 1 Physical layer (c) Sergiusz Patela Fiber-optic computer networks 7/26

8 Layers of the OSI model Layer 7 - (Application): Common protocols such as network virtual terminal, file transfer protocol (FTP), electronic mail, and directory lookup Layer 6 - (Presentation)- Encoding/decoding including compression and cryptography, terminal emulation. Layer 5 - (Session)- Communication between processes including data exchange, remote Procedure Call (RPC), synchronization, and activity management Layer 4 - (Transport)- Lowest level at which messages are handled. Segmentation and reassembly of data to and from session layer. Transmission Control Protocol (TCP), User Datagram Protocol (UDP) Layer 3 - (Network) Flow control to avoid congestion and also customer use and accounting. Link Layer Control (LLC). Internet Protocol (IP), routing protocols. Layer 2 - (Data Link) Presentation of error-free transmission to the network layer. Creates data frames and receives acknowledge frames. Media Access Control (MAC) Layer 1 - (Physical) Physical Layer Protocol (PHY) specifies coding (e.g. 4B/5B), clock synchronization. Physical Medium Dependent (PMD) sublayer provides digital communications between nodes. This layer specifies fiber-optic drivers, receivers, mechanical, cables, connectors, optical signal requirements including power levels, jitter and BER (c) Sergiusz Patela Fiber-optic computer networks 8/26

10 Protocol Protocol: standards way of dealing with data transfer Definition: A formal set of conventions governing the format and control of interactions among communicating functional units. Protocols may govern portions of a network, types of service, or administrative procedures. e.g. CSMA/CD - carrier sense multiple access / collision detection, CSMA/CA- carrier sense multiple access / collision avoidance, IP, (c) Sergiusz Patela Fiber-optic computer networks 10/26

11 Signal encoding Signal encoding is used to increase system robustness against noise. Examples: FDDI uses 4b/5b NRZI (Non-Return to Zero Invert on ones) with 125 Mb/s baud rate to achieve 100 Mb/s data rate. Ethernet uses Manchester encoding with 20 Mb/s baud rate (20 MBd) to achieve 10 Mb/s data rate. Clock High Low 0 time NRZ - used by PC Binary 1 = high Binary 0 = low NRZ - used in combination with 4b/5b by FDDI Binary 1 = transition Binary 0 = no transition Manchester - used by Ethernet Binary 1 = high to low transition Binary 0 = low to high transition (c) Sergiusz Patela Fiber-optic computer networks 11/26

12 Fiber advantages for network planers Error-free transmission over longer distances. More flexibility in planning networks, possibility to take advantage of new architectures. Ability to support higher data rates. Ease of handling, installing, and testing. Fiber can now be installed and tested in the same or less time than copper networks. Long term economic benefits over copper (over the lifetime of the network), superior reliability reduces operating costs by minimizing network outages higher bandwidth can produce considerable savings by eliminating the need to pull new cable when the network is upgraded to support higher bandwidth long distance capability allow all hub electronics to be centrally located. Centralization reduces the cost of cabling and electronics, and reduces administration and maintenance efforts. (c) Sergiusz Patela Fiber-optic computer networks 12/26

13 Fiber advantages for network engineers and technicians Fiber is immune to EMI/RFI signals. Fiber is immune to crosstalk. Fiber systems are easier to test. (For copper cabling, there are now more than 20 specified parameters for Gigabit Ethernet as opposed to two for optical fiber - attenuation and bandwidth). Fiber provides greater reliability and equipment safety. (c) Sergiusz Patela Fiber-optic computer networks 13/26

14 Short overview of fibers found in communication systems: Fibers Multimode Singlemode Panda PM 62.5/125 50/125 9/125 8/125 (c) Sergiusz Patela Fiber-optic computer networks 14/26

15 F-O Cables - short overview for networkers Number of fibers 1. Simplex 2. Zip-cord (duplex) 3. Multi-fiber fiber buffer Kevlar strength member jacket Technology 1. Tight-buffered 2. Loose tube Other names and classifications: distribution, raiser, breakout; indoor, outdoor; short distance, long distance; military grade, oceanic, PE jacket Ripcord Dielectric strength member Water swellable tape Buffer tube Fibers Dielectric central member Water swellable yarn (c) Sergiusz Patela Fiber-optic computer networks 15/26

16 Fiber-optic connector types and standards There is more then 100 types of fiber optic connectors. Main connector types are described by TIA/EIA-604 standards. They are called Fiber Optic Connector Intermateability Standards (FOCIS) and published with a document number format TIA-604-XX. To date, the following FOCIS documents exist: FOCIS 1: Biconic FOCIS 2: ST FOCIS 3: SC FOCIS 4: FC FOCIS 5: MTP/MPO FOCIS 6: Panduit FJ FOCIS 7: 3M Volition FOCIS 8: Mini-MAC (Withdrawn) FOCIS 9: Mini MPO (Withdrawn) FOCIS 10: Lucent LC FOCIS 11: Siecor SCDC/SCQC (not yet approved) FOCIS 12: Siecor/Amp MT-RJ FOCIS 15: MF FOCIS 16: LSH (LX-5) The MU currently has no FOCIS document. (c) Sergiusz Patela Fiber-optic computer networks 16/26

17 Connectors Short overview ST FC, FC/PC SC Comparison of standard and SFF connector dimensions (FC and LC) FDDI (c) Sergiusz Patela Fiber-optic computer networks 17/26

18 Outline of fiber optic network design 1. Define Environmental Requirements, e.g. office LAN vs. under-see system 2. Select Transmission Standard, e.g. Ethernet, FDDI 3. Select System Architecture (topology, fiber length, number of connectors, splices, fiber length) 4. Select Type of Fiber (MM, SM, POF, verify fiber attenuation and bandwidth) 5. Select Optoelectronic Packages (for standard or harsh environment, standard interfaces of pigtailed elements) 6. Select Type of Connector 7. Select the Cable Configuration/Type 8. Select Backshell for Multichannel (Multifiber) Connectors 9. Select Cable Clamping Method 10. Select Tools for Inspection, Cleaning and Testing 11. System Qualification (according to the proper standard) (c) Sergiusz Patela Fiber-optic computer networks 18/26

19 Calculating the cost of fiber optic network 1. Cabling-system-components cost. Cable, wall outlets, patch panels, patch cords and connectors. 2. Installation and testing cost Labor cost of cabling and termination. Cables may be packed close together, no separation from power lines is necessary. 3. Electronic cost Optoelectronic modules steadily lower their cost. Already fewer networking components is needed when fiber is used. 4. Productivity cost Fiber's better reliability minimizes data errors and requires less time and effort in troubleshooting and correcting cabling problems 5. Recabling cost (c) Sergiusz Patela Fiber-optic computer networks 19/26

20 Ethernet Picture from the presentation of dr Robert M. Metcalfa (June 1976, National Computer Conference) (c) Sergiusz Patela Fiber-optic computer networks 20/26

21 Elements of Ethernet system The Ethernet system consists of three basic elements: 1. The physical medium used to carry Ethernet signals between computers 2. A set of medium access control rules embedded in each Ethernet interface that allow multiple computers to negotiate access to the shared Ethernet channel 3. An Ethernet frame that consists of a standardized set of bits used to carry data over the system R R R Ethernet network topology (c) Sergiusz Patela Fiber-optic computer networks 21/26

22 Ethernet area networks - evolution of LAN technology LAN Local Area Network CAN Campus Area Network MAN Metropolitan Area Network WAN Wide Area Network 10Base F 100Base FX 100Base SX 1000Base SX 100Base LX 802.3z 10GBE 802.3ae (c) Sergiusz Patela Fiber-optic computer networks 22/26

23 Networking with fibers - recommendations (1/2) Application Baud Rate Mbaud Horizontal < 100 M Media TX Building < 300 m Media TX Campus < 2,000 m Media TX 10BaseF 20 MM S MM S MM S Token Ring 32 MM S MM S MM S 100VG- 120 MM S MM S MM LE AnyLAN 100BaseF 125 MM S MM S MM LE 1000Base-SX 1250 MM SL MM SL 1000Base-LX 1250 MM LL MM LL SM LL FDDI 125 MM S MM S MM LE S 850nm LED, SL 850nm LD, LE 1300nm LED; LL 1300nm LD By Fiber Optics LAN Section (FOLS) of the Telecommunications Industry Association (TIA) (c) Sergiusz Patela Fiber-optic computer networks 23/26

24 Networking with fibers - recommendations (2/2) Application Baud Rate Mbaud Horizontal < 100 M Media TX Building < 300 m Media TX Campus < 2,000 m Media TX Fibre Channel MM S MM SL/LE MM SL/LE MM SL MM S MM SL/LE MM SL/LE MM SL MM LE SM LL SM LL SM LL SDH/Sonet /ATM MM S MM SL/LE MM SL/LE MM SL MM SL MM S MM SL/LE MM SL/LE MM SL MM SL MM LE MM SL/LE SM LL SM LL SM LL S 850nm LED, SL 850nm LD, LE 1300nm LED; LL 1300nm LD By Fiber Optics LAN Section (FOLS) of the Telecommunications Industry Association (TIA) (c) Sergiusz Patela Fiber-optic computer networks 24/26

25 Summary Optical fiber provides users with higher reliability, superior performance and greater flexibility than copperbased systems. The construction of optical fiber makes it essentially immune to many of the factors that adversely impact copper, factors that often become more pronounced at higher data rates, thereby increasing network cost and complexity. (c) Sergiusz Patela Fiber-optic computer networks 25/26

26 Control questions 1. What are the basic network types? How introduction of optical fibers modifies the traditional classification? 2. Describe OSI layered network model. Explain which layers are influenced by the presence of different photonics elements. 3. List fiber advantages. Indicate which are important for network planners, engineers and users. 4. Which computer-networks are suitable for optical fiber networking. Shortly characterize active and passive optoelectronics elements of the network. How selection of the elements influences network design? 5. Describe optoelectronic elements (passive and active ) used in Ethernet networks. (c) Sergiusz Patela Fiber-optic computer networks 26/26