Meaning of BN in English
BECN Cell: A Resource Management (RM) cell type indicator. A Backwards Explicit Congestion Notification (BECN) RM-cell may be generated by the network or the destination. To do so, BN=1 is set, to indicate the cell is not source-generated, and DIR=1 to indicate the backward flow. Source generated RM-cells are initialized with BN=0.
Bridge Number: A locally administered bridge ID used in Source Route Bridging to uniquely identify a route between two LANs.
ATM Forum English vocabulary. Английский словарь организации Форум ATM. 2012