Table of Contents

BPX Network Interface Group
BXM Cards, Trunk Mode Summary
Broadband Network Interface Cards (BNI-T3 and BNI-E3)

Features
Functional Description

Egress
Ingress
PLPP— Receiver Side
PLPP—Transmitter Side
Bandwidth Control
Loopbacks and Diagnostics

Front Panel Indicators

T3 and E3 Line Modules (LM-3T3 and LM-3E3)
Broadband Network Interface Cards, BNI-155

Features
Overview
Functional Description
Front Panel Indicators

OC3, Line Modules (SMF, SMFLR, & MMF)
Y-Cabling of BNI Backcard, SMF-2-BC

Network Interface (Trunk) Cards

This chapter contains a description of the BPX network interface (trunk) cards, including the Broadband Network Interface (BNI) and associated backcards.

This chapter contains the following:

BPX Network Interface Group

BXM Cards, Trunk Mode Summary

Broadband Network Interface Cards (BNI-T3 and BNI-E3)

T3 and E3 Line Modules (LM-3T3 and LM-3E3)

Broadband Network Interface Cards, BNI-155

OC3, Line Modules (SMF, SMFLR, & MMF)

Y-Cabling of BNI Backcard, SMF-2-BC9

BPX Network Interface Group

The BPX network interface group of cards provides the interface between the BPX and the ATM network (Figure 4-1). The BNI series of cards (DS3, E3, and OC3) are described in this chapter. The BXM card trunk operation is briefly described in this chapter with additional information provided in a later chapter. The BXM cards may be configured for either trunk or service (port UNI) mode. In trunk mode they provide BPX network interfaces.

BXM Cards, Trunk Mode Summary

The BXM card sets supports T3/E33, OC-3/STM-1, or OC-12/STM-4 interfaces, and provide the capacity to meet the needs of emerging bandwidth driven applications. The BXM cards provide high speed ATM connectivity, flexibility, and scalability. The card sets are comprised of a front card that provides the processing, management, and switching of ATM traffic and of a back card that provides the physical interface for the card set.

A BXM port may be configured to operate as either a trunk or UNI port. The BXM OC-12 back cards support either Single Mode Fiber (SMF) or Single Mode Fiber Long Reach (SMFLR). The BXM OC-3 back cards support either Multi-Mode Fiber (MMF), Single Mode Fiber (SMF), or Single Mode Fiber Long Reach (SMFLR). The BXM-T3/E3 supports T3 1.544 Mbps and E3 34.368 Mbps interfaces.

For a further description of the BXM cards refer to Chapter 6, BXM T3/E3, 155, and 622.

Figure 4-1: BPX Network Interface Group

Broadband Network Interface Cards (BNI-T3 and BNI-E3)

The BNI-T3 and BNI-E3 interface the BPX with ATM T3 and E3 broadband trunks, respectively. These ATM trunks may connect to either another BPX, an IPX equipped with an AIT card, or an AXIS Shelf.

The BNI-3T3 back card provides three DS3 interfaces on one card while 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 can be used to hold these cards. Each BNI operates as a pair with a corresponding Line Module back card.

Features

A summary of features for the BNI cards include:

• BNI-T3 provides three broadband data ports operating at 44.736 Mbps.
  BNI-E3 provides three broadband data ports operating at 34.368 Mbps.

• BNI T3 trunks can transmit up to 96,000 cells per second.
  BNI E3 trunks can transmit up to 80,000 cells per second.

• BNI-T3 utilizes the Switched Megabit Data Service (SMDS) Physical Layer Convergence Protocol (PLCP).

• BNI-E3 utilizes the CCITT G.804 framing format.

• T3 and E3 provide up to 32 class-based queues for each port.

• 24,000 cell transmit buffer per port.

• 800 Mbps backplane speed.

• Two-stage priority scheme for serving cells.

• Synchronize the electrical interface to either the line or the BPX system timing.

• Recover timing from the line for synchronizing the BPX node timing.

• Accumulates trunk statistics for T3, E3, and OC3

• Optional 1:1 card redundancy using Y-cable configuration for BNI T3 and E3.

Functional Description

The BNI T3 and E3 cards are functionally alike except for the two different electrical interfaces. Refer to Figure 4-2 illustrating 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(TM) 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.

Egress

In the transmit direction (from the BPX switching matrix towards the transmission facility, referred to as egress), the BNI performs the following functions:

• Software controlled line buildout to match up to 900 feet (275 meters) of ABAM cable.

• Receives incoming cells from the switch matrix on the BCC.

• Queues and serves the cells based on the class-of-service algorithm.

• Sets congestion indication (EFCN) in cell header when necessary.

• Adds frame sync pattern and PLCP or G.804 overhead and transmits cells onto the T3 or E3 trunk.

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

Some of the functions performed by the PLPP in the BNI-3T3 include:

PLPP— Receiver Side

• Provides frame sync for either the M23 or C-bit parity frame format.

• Provides alarm detection and accumulates B3ZS code violations, framing errors, parity errors, C-bit parity errors, and far end bit error (FEBE) events.

• Detects far end alarm channel codes, yellow alarm, and loss of frame.

• Provides optional cell descrambling, header check sequence (HCS) error detection, and cell filtering.

• Small receive FIFO buffer for incoming cells.

PLPP—Transmitter Side

• Inserts proper frame bit sequence into outgoing bit stream.

• Inserts proper alarm codes to be transmitted to the far end.

• Provides optional ATM cell scrambling, HCS generation and insertion, and programmable null cell generation.

• Small transmit FIFO for outgoing cells.

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.

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 IPX 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. A non-disruptive self test is automatically performed on a routine basis. A more complete, disruptive test 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 (see Table 4-5).

Several loopback paths are provided. A digital card loopback path, used by the node for self-test, loops the data at the serial DS3 or E3 interface back towards the node. A digital line loopback 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.

There are several loopback paths within the BNI for testing. A digital loopback at the DS3 or E3 transmitter/receiver to check both the transmit and receive signal paths in the near-end BNI card. These loopbacks loop the signal in both directions, towards the StrataBus as well as towards the output. Therefore, they can be used to support both near end and far end maintenance loopback testing. On the BNI-3T3, there is a digital loopback capability to the PLPP processor used for the internal self test to basically check the operation of the signal processor.

Once a trunk has been assigned to a BNI card but before it is made active (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 (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.

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 and the LM-3E3 with the BNI-3E3. The Line Module connects to the BNI through the StrataBus midplane. Two adjacent cards of the same type can be made redundant by using a Y-cable at the port connectors. All three ports on a card must be configured the same.

Refer to Figure 4-4, Figure 4-5, and Table 4-3 which describe the faceplate connectors of the LM-3T3 and LM-3E3. There are no controls or indicators.

The LM-3T3 provides the following features:

Broadband Network Interface Cards, BNI-155

The BNI-155 interfaces the BPX with ATM OC3/STM-1 broadband trunks. The ATM trunk may connect to either another BPX or customer CPE equipped with an ATM OC3/STM-1 interface.

There are three BNI-155 back cards, the LM-2OC3-SMF for single-mode fiber intermediate range, the LM-2OC3-SMFLR for single-mode fiber long range, and the LM-2OC3-MMF for multi-mode fiber. Any of the 12 general purpose slots can be used to hold these cards. These backcards may also be used with the ASI-155.

Features

A summary of features for the BNI-155 cards include:

• LM-OC3-SMF and LM-OC3-MMF cards provide two ports, each operating at 155.52 Mbps.

• Up to 353,208 cells per second

• Up to 12 class-based queues for each port

• 8 K cell ingress (receive) VBR buffer.

• 32 K cell egress (transmit) buffers

• 800 Mbps backplane speed.

• Two-stage priority scheme for serving cells.

• Accumulates trunk statistics for OC3/STM-1

• Optional 1:1 card redundancy using Y-cable configuration for BNI-155.

Overview

Egress

In the transmit direction (from the BPX switching matrix towards the transmission facility, referred to as egress), the BNI performs the following functions (Figure 4-6):

• Receives incoming cells from the switch matrix on the BCC.

• Serves the cells based on the class-of-service algorithm.

• Sets congestion indication (EFCN) in cell header when necessary.

Ingress

In the receive direction (from the transmission facility towards the BPX switching matrix, referred to as ingress), the BNI performs the following functions (Figure 4-6):

• Receives incoming ATM cells from the OC3 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/Virtual Circuit Identifier (VPI/VCI) in the cell header.

Functional Description

In the egress direction, the BNI-155 has 2 Queue Service Engine (QSEs) which provide each of the ports with 12 programmable queues with selectable parameters such as minimum bandwidth, priority, and maximum bandwidth. The BNI queues are based on a class of service algorithm. The BNI supports the following trunk queues:

• Voice

• Non-Time Stamped

• Time Stamped

• Bursty Data A

• Bursty Data B

• High Priority (Network Management Traffic)

• CBR

• VBR

In the ingress direction, the BNI-155 has 2 Cell Input Engines (CIEs) that convert the incoming cell headers to the appropriate connection ID based on input from a Network Address Table.

The Serial Interface Unit (SIU) provides the BNI with an 800 Mbps cell interface to the StrataBus. It provides serial-to-parallel conversion of data, along with loopback and test signal generation capabilities.

The Line Interface Unit (LIU)performs the following ingress functions:

• Provides framing detection and synchronization.

• Provides the ability to extract timing from the incoming signal, and use it as a receive clock for incoming data, while providing transmit clock in the other direction. Alternatively, loop timing can be used to turn the receive clock back around to be used as a transmit clock. The receive clock may also be used to synchronize the node.

• Detects alarms, frame errors, and parity errors.

• Detects far end errors, including framing errors, and yellow alarm indications.

• Provides optional cell descrambling, header error check (HEC), and idle cell filtering.

• Provides a small FIFO buffer for incoming cells.

• Provides optical to electrical conversion.

The Line Interface Unit (LIU) performs the following egress functions:

• Inserts the appropriate framing into the outgoing bit stream.

• Inserts any alarm codes for transmission to the far end.

• Provides optional cell scrambling, HEC generation, and idle cell insertion.

• Provides a small FIFO buffer outing cells.

• Provides electrical to optical conversion.

Figure 4-6: Simplified BNI-155 Block Diagram

Front Panel Indicators

The BNI-155 front panel (Figure 4-7) has a three-section, multicolored "card" LED to indicate the card status. The card status LED is color-coded as indicated in Table 4-4. A three-section multicolored "port" LED indicates the status of the two ports on the BNI-155. Types of failures are indicated by various combinations of the card status indicators as indicated in Table 4-5.

BNI-155 Front Panel

OC3, Line Modules (SMF, SMFLR, & MMF)

The Line Modules for the OC3 BNI cards are back cards used to provide a physical interface to the transmission facility. There are three types, a single-mode fiber intermediate range, single-mode fiber long range, and a multi-mode fiber backcard. The Line Modules connect to the BNI through the StrataBus midplane.

For connector information, refer to Figure 4-8 and Table 4-6 for the LM-OC3-SMF and to Figure 4-9 and Table 4-7 for the LM-OC3-MMF. The LM-OC3-SMFLR uses the same type of connectors as the LM-OC3-SMF.

Y-Cabling of BNI Backcard, SMF-2-BC

The LM-OC3-SMF (Model SMF-2-BC) backcards may be Y-cabled for redundancy using the Y-Cable splitter shown in Figure 4-10. The cards must be configured for Y-Cable redundancy using the addyred command.

Figure 4-10: Y-Cable (Model SMFY), LC-OC3-SMF (Model SMF-2-BC)

Posted: Wed Jan 17 21:22:34 PST 2001
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