4-4 Cisco BPX 8600 Series Reference
Broadband Network Interface Cards (BNI-T3 and BNI-E3)
Ingress
In the receive direction (from the transmission facility towards the BPX switching matrix, sometimes
referred to as ingress), the BNI performs the following functions:
• Receives incoming ATM cells from the DS3 transmission facility, stripping the framing and
overhead from the received bit stream.
• Determines the address of the incoming cells by scanning the Virtual Path Identifier (VPI)/Virtual
Circuit Identifier (VCI) in the cell header.
• Queues the cells for transmission through the switch matrix.
• Extracts receive timing from the input framing and makes it available for node timing. Line can
operate in looped timing mode.
• Recovers clock and data from the bipolar B3ZS (T3) or HDB3 (E3) line signal and converts data
to unipolar.
Figure 4-2 Simplified BNI-T3, BNI-E3 Block Diagram
StrataBus backplane
H8153
DS3 #1
DS3 #2
DS3 #3
E3 #1
E3 #2
E3 #3
BNI-3E3 only
BNI-3T3 only
Comm.
bus
interface
Control
& admin.
processor
Network
address
table
Queue service
engine #1
DS3 function
block (PLPP)
G.832 framer
E3 xmtr/rcvr
G.832 framer
E3 xmtr/rcvr
G.832 framer
E3 xmtr/rcvr
DS3 function
block (PLPP)
DS3 function
block (PLPP)
Queue service
engine #2
Queue service
engine #3
Serial
interface
module
(SIM)
