Bandwidth Control; Loopbacks And Diagnostics; Table - Cisco BPX-BXM-155-8DX Installation And Configuration Manual

Chapter 4 BNI (Trunk) Cards
In the BNI-3E3 the PLPP is replaced by a G.804 framer. The E3 framer obtains end-to-end
synchronization on the Frame Alignment bytes. And a E3 transmitter/receiver replaces the DS3
transmitter/receiver for the BNI-3E3.
Another major BNI function is queuing of the ATM cells waiting to be transmitted to the network trunk.
This is controlled by the Queue Service Engine. There are 32 queues for each of the three ports to
support 32 classes of service, each with its programmable parameters such as minimum bandwidth,
maximum bandwidth, and priority. Queue depth is constantly monitored to provide congestion
notification (EFCN) status. The Queue Service Engine also implements a discard mechanism for the
cells tagged with Cell Loss Priority.
The destination of each cell is contained in the Virtual Path Identifier/Virtual Circuit Identifier
VPI/VCI) field of the cell header. This is translated to a Logical Connection Number via table lookup
in the Network Address Table. Both terminating and through connections can coexist on a port.
A Serial Interface Module (SIM) provides cell interface to the StrataBus backplane. This operates at
800 Mbps. It provides a serial-to-parallel conversion of the data and loopback and pseudo-random bit
generation for test purposes.
Both BNI-T3 and BNI-E3 cards support two clock modes that are selected by the system operator
through software control. Normal clocking uses receive clock from the network or user device for
incoming data and supplies transmit clock for outgoing data. The clock obtained can be used to
synchronize the node if desired. Loop timing uses receive clock from the network for the incoming data
and turns that same clock around for timing the transmit data to the network or connecting CSU.

Bandwidth Control

The transmit bandwidth can be throttled down for certain applications. For example, when interfacing
with an older IPX switch E3 ATM Trunk Card, the trunk transmit rate is limited to 40,000 cells/second.
If a T2 trunk adapter is used, the trunk transmit rate is limited to 14,000 cells/second.

Loopbacks and Diagnostics

There are two types of self-tests that may be performed:
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Loopback paths are provided:
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Internally, the PLPP circuit in the BNI-T3 has several loopbacks for use by diagnostic routines. These
loopbacks loop the signal in both directions, toward the StrataBus as well as toward the output.
Therefore, they can be used to support both near-end and far-end maintenance loopback testing:
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Release 9.3.0, Part Number 78-10674-01 Rev. D0, July 2001
A non-disruptive self test
This is automatically performed on a routine basis.
A more complete, disruptive test
This may be initiated manually when a card failure is suspected. If the card self-test detects a
failure, the card status LEDs displays an indication of the failure type.
A digital card loopback path
This is used by the node for self-test. It loops the data at the serial DS3 or E3 interface back toward
the node.
A digital line loopback
This loops the data at the electrical transmitter/receiver at the card output.
A digital loopback at the DS3 or E3 transmitter/receiver
This checks both the transmit and receive signal paths in the near-end BNI card.
Broadband Network Interface Cards (BNI-T3 and BNI-E3)
Cisco BPX 8600 Series Installation and Configuration
4-5