- Asked 2/11
- 2072 Chaitra
- 2074 Chaitra · 4 marks
FDDI features
Short answer
FDDI is a 100 Mbps dual-ring fibre LAN with token passing, self-healing, up to 100 km, and 500 stations. It uses 4B/5B encoding, early token release, and supports synchronous/asynchronous traffic with Class A and B stations.
List the features of FDDI. (Short note: FDDI.)
FDDI (Fiber Distributed Data Interface) is a high-speed LAN/MAN standard (ANSI X3T9.5) that uses fibre optic cable in a dual counter-rotating ring topology at 100 Mbps with token passing.
Features
- Speed: 100 Mbps data rate.
- Medium: multimode fibre (62.5/125 micron), also supports copper (CDDI, UTP/STP).
- Topology: two counter-rotating rings, primary and secondary. The secondary is a backup that is used when the primary breaks, giving fault tolerance (self-healing by wrapping the ring).
- Distance: up to 100 km ring length and up to 2 km between stations, with up to 500 stations (1000 connections).
- Access method: timed token passing. A station captures the token to send frames and releases a new token after transmission (early token release).
- Reliability and security: immune to EMI, hard to tap.
- Station types: Class A (dual attachment, on both rings) and Class B (single attachment, via a concentrator).
- Encoding: 4B/5B with NRZI.
- Supports synchronous (time-sensitive) and asynchronous traffic.
- Frame size up to 4500 bytes.
Used as a backbone for LANs and campus networks, now replaced by Gigabit Ethernet.
✓ Answer checked by Claude Opus 5.5 (high effort)