Distributed Queue Dual Bus (DQDB, 802.6)
A dual media data link layer with variable (high bandwidth ) transmission rates
ANSI DS3 44.736 Mb/ s over coaxial cable or optical fibre
ANSI SONET higher rates over single-mode optical fibre (CCIT)
CCIT G.703 34.368 Mb/ s or 139 Mb/ s over metallic media