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Overview

FDDI

Overview

• Target Installations
  • Campus/premises wide backbone for LANs

  • Interconnection of fast workstations

  • MAN - see DGDB

• Statistics
  • 100 Mbps (Mega bits per second)

  • 500 nodes

  • Maximum 2 km between workstations (no minimum)

  • Total ring length 100 km as a dual ring (200km as a single ring)

• Concept
  • Two counter rotating fibre optic rings

  • Token based data transmission

  • Fault tolerant - dual ring wraps to single ring if a fibre fails

• ANSI is the main standards authority for FDDI (ISO approval follows)
  • ANSI X3T9.5 renamed in 1995 to X3T12
    • eg. Physical Layer Model ANSI X3.139 -1987 (ISO 9314-1:1989)

  • ISO 9314

• FDDI was developed from the token ring standard IEEE802.5

FDDI ANSI Standard

• 4 key components: MAC - Media Access Control; PHY -physical layer; PMD - physical media dependent; and SMT station management protocol

• MAC defines addressing, scheduling, data routing and communication with potocols such as TCP/IP

• PHY handles encoding/decoding, NRZI modulation and clock synchronisation

• PMD handles analog baseband transmission between nodes - fibre and copper

• SMT handles ring management including neighbour identification, fault detection and reconfiguration

FDDI

WWW Sites

• Internet access: URL http://sholeh.nswc.navy.mil/X3T12
  • FAQs

  • FTP sites

  • Standard documents are not on-line - printed copies only

  • Try http://web.syr.edu/~jmwobus/lans/ for general LAN information