1. 1 Fibre Distributed Data Interface 100Mbps –1986 ANSI - X3T9.5 committee –Supports IEEE 802.5 Access Methodology = Modified token-passing Logical topology = sequential Physical = Dual counter-rotating rings

2. 2 Dual-Ring Topology

3. 3 Subnets

4. 4 Dual-Ring Topology Primary ring –Traffic –FDDI Reconfigures the network Redundancy –Transmission –Cable Failure –Ring Failure The total cable length of both rings combined must not exceed 200 km, and it cannot hold more than 1000 computers.

5. 5 Topology FDDI operates at 100 Mbps over a dual-ring topology that supports 500 computers over a distance of up to 100 km More than one computer at a time can transmit Capacities should be divided in half. –FDDI network should be limited to 500 computers and 100 km of cable.

6. 6 FDDI (continued) A FDDI network

7. 7 FDDI Connects large and small minicomputers Back-end networks FDDI works with backbone networks to which other low-capacity LANs can connect LANs that require high data rates File transfer, Video, CAD & CAM

8. 8 FDDI in Star FDDI computers can accommodate point-to-point links to a hub.

9. 9 Built-in reliability High degree of reliability and security –EMI –RFI Two Rings –Primary ring – data –Secondary ring – backup –Single Hub or connector 500 nodes at 2km apart SAS – single attachment station DAS – dual attachment stations

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11. 11 Built-in Reliability

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13. 13 FDDI Uses Beaconing 34

14. 14 Beaconing With beaconing, the computer that detects a fault sends a signal, called a "beacon," onto the network. The computer continues to send the beacon until it notices a beacon from its upstream neighbour, and then it stops sending.

15. 15 Standards Distances in FDDI LAN Impractical to turn a free token to busy Physically removes token and transmits an entire Data Frame. Numerous messages can be sent Synchronous Frames

16. 16 Modified Token Passing Transmits as many frames as it can produce within a predetermined. There can be several frames circulating on the ring at once. Higher throughput than a Token Ring network, which allows only one frame at a time to circulate.

17. 17 Application of FDDI Bandwidth drivers fall into two categories: Network Architecture Trends Network Application Trends LANs = more and more users FDDI networks form the backbone

18. 18 Campus Backbone Connecting LANs located throughout a series of closely situated buildings. Ring circumference can equal 200 km Multiple FDDI LANs 100 Mbps FDDI building backbone –Connecting numerous 10-Mbps Ethernet –Servers connected via connectors

19. 19 Backbone

20. 20 High-Bandwidth Workgroups FDDI LANs connecting as few as 20 computers –High-bandwidth communication –CAD/CAM Workstations Power Users –GUI

21. 21 High-Bandwidth Subgroups In some cases only 2 or 3 devices such as servers, require high-bandwidth. Increased demand –Distributed Computing –Data Distribution

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