Specifications

Common Equipment Description 2-21
BNM-155
The major function of the BNM-155 is to provide a 155 Mbps SONET ATM interface to a
BXM-8-155 port or a BXM-4-155 port in a BPX 8620 node. The BNM-155 also provides a number
of miscellaneous functions as follows:
• Shelf Mastership
This function selects which core card to use as the master and which redundant bus to use.
• Cell Bus Mastership
BNM-155 polls the other cards on the bus and grants permission to transmit cells across the bus.
Polling is performed on a round-robin basis.
• Clock Selection
BNM-155 manages the clock selection and synchronization for the entire MGX 8220 shelf. The
BNM-155 selects, regulates, and outputs the selected clock for use by each service module in the
shelf. The BNM-155 back card contains a T1/E1 port for inputting an external T1/E1 clock
source (both DB15 and BNC are available). The shelf can also obtain its clock source from the
SONET trunk itself or use an internal clock source.
• External Alarm Interface
BNM-155 provides the activation of four alarm relays which are wired to a DB-15 connector on
the back card faceplate allowing the customer to wire their own cable from the connector to an
indicator panel. The four relays are Major Alarm Audible, Major Alarm Visual, Minor Alarm
Audible, and Minor Alarm Visual. The pinouts for this connector are provided in Appendix B,
“Specifications”.
• Miscellaneous Monitoring Functions:
— Fan performance in the Cooling Assembly
— Input voltage levels
— Shelf intake air temperature
— In-band management
The BNM-155 card provides a separate path for management of the MGX 8220 shelf using an ATM
VCC from across the ATM network.Specifications
ATM Trunk Interface
The BNM-155 card accepts and transmits ATM 53-byte cells over a SONET line interface at
155.52 Mbps using ATM UNI or ATM B-ICI protocols.
In UNI mode, 20 virtual circuit connections per slot are supported.
In NNI mode, 340 virtual circuit connections per slot are supported.