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Table Of Contents
BPX Switch Network Interface Group
Broadband Network Interface Cards (BNI-T3 and BNI-E3)
T3 and E3 Line Modules (LM-3T3 and LM-3E3)
OC-3, Line Modules (SMF, SMFLR, & MMF)
Y-Cabling of BNI Back Card, SMF-2-BC
BNI (Trunk) Cards
This chapter describes the Broadband Network Interface (BNI) card and associated back cards.
Contents of this chapter include:
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BPX Switch Network Interface Group
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BPX Switch Network Interface Group
The BPX switch network interface group of cards provides the interface between the BPX switch and the ATM network (see Figure 4-1).
Figure 4-1 BPX Switch Network Interface Group
Broadband Network Interface Cards (BNI-T3 and BNI-E3)
The BNI-T3 and BNI-E3 interface the BPX switch with ATM T3 and E3 broadband trunks, respectively. These ATM trunks may connect to either:
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The BNI-3T3 back card provides three DS3 interfaces on one card. The BNI-E3 back card provides three E3 interface ports. The BNI back card types are very similar, differing only in the electrical interface and framing.
Any of the 12 general purpose slots may be used to hold these cards. Each BNI operates as a pair with a corresponding Line Module back card.
Features
The BNI card features include:
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BNI-E3 provides three broadband data ports operating at 34.368 Mbps.•
BNI E3 trunks can transmit up to 80,000 cells per second.•
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Functional Description
The BNI T3 and E3 cards are functionally alike except for the two different electrical interfaces. Figure 4-2 illustrates the main functional blocks in the BNI-3T3 card.
The DS3 port interface on the BNI-T3 card is the DS3 Function Block, a Physical Layer Protocol Processor (PLPP) custom semiconductor device, which implements the functions required by the DS3 PLCP as defined in various AT&T` technical advisories. This VLSI device operates as a complete DS3 transmitter/receiver. Each BNI-3T3 has three of these devices, one for each of the DS3 ports on the card.
In the transmit direction (from the BPX switching matrix towards the transmission facility, referred to as egress), the BNI performs these functions:
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In the receive direction (from the transmission facility towards the BPX switching matrix, sometimes referred to as ingress), the BNI performs these functions:
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Figure 4-2 Simplified BNI-T3, BNI-E3 Block Diagram
Some of the functions performed by the PLPP in the BNI-3T3 include:
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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 can be performed:
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This is automatically performed on a routine basis.•
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.Loopback paths are provided:
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This is used by the node for self-test. It loops the data at the serial DS3 or E3 interface back toward the node.•
This loops the data at the electrical transmitter/receiver at the card output.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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This checks both the transmit and receive signal paths in the near-end BNI card.•
This is used for the internal self test to basically check the operation of the signal processor.When a trunk has been assigned to a BNI card but is not yet activated (upped), it is put in a loopback mode and a diagnostic test is continuously performed. This loopback is disruptive so it cannot be performed on a card that has an active trunk. This diagnostic test checks the data path through the BNI out to the BCC, through the switch matrix, and back to the BNI.
Active trunks are constantly checked by the Communications Fail test routine which is part of system software.
Front Panel Indicators
The lower section of the BNI front panel (see Figure 4-3) has a three-section, multicolored LED to indicate the card status. The card status LED is color-coded as indicated in Table 4-1.
At the upper portion of the front panel, there is a three-section multicolored LED to indicate the status of the three ports on the BNI. Types of failures are indicated by various combinations of the card status indicators as indicated in Table 4-2.
Figure 4-3 BNI-3T3 Front Panel (BNI-3E3 appears the same except for name)
T3 and E3 Line Modules (LM-3T3 and LM-3E3)
The Line Modules for the BNI-T3 and BNI-E3 front cards are back cards used to provide a physical interface to the transmission facility. The LM-3T3 is used with the BNI-T3. The LM-3E3 with the BNI-3E3.
The Line Module connects to the BNI through the StrataBus midplane. You can make two adjacent cards of the same type redundant by using a Y-cable at the port connectors. All three ports on a card must be configured the same.
The LM-3T3 and LM-3E3 provides the following features:
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A final node loopback is at the end of the LM-3T3 or LM-3E3 card. This is a metallic loopback path that uses a relay contact closure. It is a near-end loopback path only; the signal is looped at the final output stage back to circuits in the node receive side. It is operated only when the corresponding front card is in standby.
The faceplate connectors of the LM-3T3 and LM-3E3 are described in Table 4-3. There are no controls or indicators.
Figure 4-4 illustrates a typical LM-3T3 faceplate.
Figure 4-4 LM-3T3 Faceplate, Typical
Figure 4-5 illustrates a typical LM-3E3 faceplate.
Figure 4-5 LM-3E3 Faceplate, Typical
OC-3, Line Modules (SMF, SMFLR, & MMF)
The Line Modules for the OC-3 BNI cards are back cards provide a physical interface to the transmission facility. The following are the three types:
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The Line Modules connect to the BNI through the StrataBus midplane.
For connector information, see and for the LM-OC-3-SMF along with
The LM-OC-3-SMFLR uses the same type of connectors as the LM-OC-3-SMF.
The connector information for LM-OC3-SMF and LM-OC-3-SMFLR is described in Table 4-4.
The connector information for LM-OC-3-MMF is described in Table 4-5.
Figure 4-6 illustrates the LM-OC-3-SMF faceplate.
Figure 4-6 LM-2OC-3-SMF Faceplate
Figure 4-7 illustrates the LM-OC-3-MMF faceplate.
Figure 4-7 LM-2OC-3-MMF Faceplate
Y-Cabling of BNI Back Card, SMF-2-BC
The LM-OC-3-SMF (Model SMF-2-BC) back cards may be Y-cabled for redundancy by using the Y-Cable splitter shown in Figure 4-8. You must configure the cards for Y-Cable redundancy by using the addyred command.
Figure 4-8 Y-Cable (Model SMFY), LC-OC-3-SMF (Model SMF-2-BC)
Posted: Tue May 10 21:05:37 PDT 2005
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