IEEE 802.6
IEEE 802.6 is an ANSI standard for Metropolitan Area Networks (MAN). It is an improvement of the older Fiber Distributed Data Interface - network structure (FDDI).
The disadvantage of the FDDI standard is the high implementation costs and the lack of compatibility with current LAN standards. 802.6, on the other hand, uses the Distributed Queue Dual Bus Protocol (DQDB) for data transmission , allows transfer rates of up to 150 Mbit / s and consists of two unidirectional data buses that are not connected to one another . DQDB allows a range of up to 160 km over fiber optic cables at a wavelength of 1300 nm before a signal reduction occurs.
Similar to FDDI, 802.6 is used very rarely, mostly for the same reasons. Most MANs use Synchronous Optical Network (SONET) or Asynchronous Transfer Mode (ATM) instead for data transmission .