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Cisco MGX 8220 Installation and Configuration
Release 5.0, Part Number 78-6430-03 Rev. D0, November 2003
Chapter
Core Module Overview
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 Cisco BPX 8600 series node. The BNM-155 also provides the following
miscellaneous functions:
• 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 Cisco 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 D-15 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 that 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
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Fan performance in the cooling assembly
–
Input voltage levels
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Shelf intake air temperature
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In-band management
The BNM-155 provides a separate path for management of the Cisco MGX 8220 shelf using an ATM
VCC from across the ATM network.
ATM Trunk Interface Back Card
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.
SMF-155 Back Card
The SMF-155 back card provides a physical single-mode fiber optic SONET OC-3 interface
conforming to ANSI T1.105 and GR-253-CORE standards. This interface uses SC connectors. When
used in a redundant configuration, redundant cabling is provided through Y-cables.
The back card also provides
• One-DB-15 female connector for T1/E1 clock input
• One-BNC connector for E1 clock input
• One-DB-15 female connector for alarm interface