Hardware Platform Overview
*The physical maximum number of line cards you can install is 28; however, redundant configurations may use fewer than the physical maximum number of line cards since they are not required behind standby PACs.

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Chassis: Supports 16 front-loading slots for application cards and 32 rear-loading slots for line cards.
The chassis ships with blanking panels over every slot except the following: 1, 8, 17, and 24. These are intentionally left uncovered for initial installation of application and line cards.
Refer to the ST16 Chassis Descriptions section for additional information.
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Mounting brackets: Support installation in a standard 19-inch rack or telecommunications cabinet. Standard and mid-mount options are supported. In addition, each bracket contains an electro-static discharge jack for use when handling equipment.
Refer to the Mounting Options section for additional information.
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Upper fan tray: Draws air up through the chassis for cooling and ventilation. It then exhausts air through the vents at the upper-rear of the chassis.
Refer to the Fan Tray Assemblies section for additional information.
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Upper bezel: Covers the upper fan tray bay.
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Lower fan tray cover: Secures the lower fan tray assembly in place. The cover also provides an air baffle allowing air to enter into the chassis.
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Lower bezel: Covers the lower fan tray bay.
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Lower fan tray assembly: Draws air through the chassis’ front and sides for cooling and ventilation. It is equipped with a particulate air filter to prevent dust and debris from entering the system.
Refer to the Fan Tray Assemblies section for additional information.
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Power Filter Units (PFUs): Each of the system’s two PFUs provides -48 VDC power to the chassis and its associated cards. Each load-sharing PFU operates independently of the other to ensure maximum power feed redundancy.
Refer to the Power Filter Units section for more information.
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Rear-installed line cards must be installed directly behind their respective front-loaded application card. For example, an application card in Slot 1 must have a corresponding line card in Slot 17. The redundant line card for this configuration would be placed in Slot 33. This establishes a directly mapped communication path through the chassis midplane between the application and line cards.
To help identify which rear slot corresponds with the front-loaded application card, note that the upper rear slot numbers are equal to the slot number of the front-loaded card plus 16. For example, to insert a line card to support an application card installed in slot 1, add 16 to the slot number of the front-loaded application card (Slot 1 + 16 slots = Slot 17). Slot 17 is the upper right-most slot on the rear of the chassis, directly behind Slot 1.
For lower rear slot numbers, add 32. Again, a redundant line card for an application card in Slot 1 would be (Slot 1 + 32 = Slot 33). Slot 33 is the lower right-most slot on the rear of the chassis, also behind Slot 1.
The chassis is designed for installation in a standard 19-inch wide (48.26 cm) equipment rack. Additional rack hardware (such as extension brackets) may be used to install the chassis in a standard 23-inch (58.42 cm) rack. Each chassis is 24.50 inches (62.23 cm) high. This equates to roughly 14 Rack Mount Units (RMUs: 1 RMU = 1.75 in (4.45 cm).
You can mount a maximum of three chassis in a standard 48 RMU (7 feet) equipment rack or telco cabinet provided that all system cooling and ventilation requirements are met. A fully-loaded rack with three chassis installed has approximately 5.5 inches (13.97 cm, 3.14 RMUs) of vertical space remaining.
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Standard: In this configuration, the flanges of the mounting brackets are flush with the front of the chassis. This is the default configuration as shipped.
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Mid-mount: In this configuration, the flanges of the mounting brackets are recessed from the front of the chassis. To do this, install the mounting brackets toward the middle of the chassis on either side.
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Separating the front and rear chassis slots is the midplane. The connectors on the midplane provide intra-chassis communications, power connections, and data transport paths between the various installed cards.
Hosted on the Switch Processor Card (SPC), this IP-based, or packetized, switch fabric provides a transport path for user data throughout the system. The 320 Gbps switch fabric establishes inter-card communication between the SPC(s) and other application cards within the chassis, and their respective line cards.
The Control Bus features redundant 32 Gbps Ethernet paths that interconnect all control and management processors within the system. The bus uses a full-duplex Gigabit Ethernet (GE) switching hierarchy from both SPCs to each of the 14 application card slots in the chassis. Each application card is provisioned with a GE switch to meet its specific needs. This bus also interconnects the two SPC modules.
The System Management Bus supports management access to each component within the chassis. It provides a communication path from each SPC to every card in the system supporting a 1 Mbps transfer rate to each card. This allows the SPCs to manage several low-level system functions, such as supplying power, monitoring temperature, board status, pending card removals, and data path errors, and controlling redundant/secondary path switchovers, card resets, and other failover features. Additionally, the System Management Bus monitors and controls the fan trays, power filter units, and alarming functions.
Each serial link facilitates up to 5 Gbps symbol rate, equivalent to 4 Gbps of user data traffic, in each direction. Therefore, the Redundancy Bus provides 140 Gbps symbol rate (112 Gbps user data) of throughput per RCC, 280 Gbps symbol rate (224 Gbps user data) total for both.
The system also hosts a dual OC-48 TDM bus consisting of 128 independent TDM paths each consisting of 512 DS0 channels. This bus supports voice services on the system. Higher speed TDM traffic requirements are addressed using the system’s data fabric.
To provide redundancy between Switch Processor I/O (SPIO) cards, the system possesses a physical interconnect between the ports on the SPIOs. This cross-connect allows management traffic or alarm outputs to be migrated from an active SPIO experiencing a failure to the redundant SPIO.
Located at the bottom rear of the chassis are slots for two Power Filter Unit (PFU) assemblies. Each PFU provides DC power from the Central Office (CO) battery sub-system to the chassis and its associated cards. Each load-sharing PFU operates independently of the other to ensure maximum power feed redundancy. The maximum input operating voltage range of the PFU is -40 VDC to -60 VDC; the nominal rage is -48 VDC to -60 VDC.
There are two versions of the PFU. The versions are differentiated by the current rating of the circuit breakers: 125 amp and 165 amp. Older versions of the ST16 chassis use the 125A PFU. Newer versions of the ST16 chassis use the 165A PFU.
The following drawing shows the PFU and its connectors. Refer to the
Cabling the Power Filter Units chapter for information on installing and cabling the PF.
There are two fan tray assemblies within the chassis. A lower fan tray provides air intake and an upper fan tray exhausts warmed air from the chassis. Each fan tray is connected to both PFUs to ensure power feed redundancy. Both fan tray assemblies are variable speed units that are automatically adjusted based on temperature or failover situations.
Thermal sensors monitor temperatures within the chassis. In the event of a fan failure or other temperature-related condition, the Switch Processor Card/Switch Management Card SPC notifies all operable fans in the system to switch to high speed and generates an alarm.
The lower fan tray assembly contains multiple fans and pulls air into the chassis from the lower front and sides of the chassis. The air is then pushed upward across the various cards and midplane within the chassis to support vertical convection cooling.
The chassis supports a replaceable particulate air filter that meets UL 94-HF-1 standards for NEBS-compliant electronics filtering applications. This filter is mounted at the top of the lower fan tray assembly, providing ingress filtering to remove contaminants before they enter the system. Temperature sensors measure the temperature at various points throughout the chassis. The system monitors this information, and if it detects a clogged filter, generates a maintenance alarm.
Airflow within the chassis is designed per Telcordia recommendations to ensure the proper vertical convection cooling of the system. Detailed information is located in the
Chassis Air Flow section in
Environmental Specifications chapter of this guide.
The SPC serves as the primary controller for the ST16 hardware platform and is used with Packet Accelerator Cards (PACs). The SPC initializes the entire system and loads the software’s configuration image into other cards in the chassis, as applicable. SPCs are installed in slots 8 and 9. During normal operation, the SPC in slot 8 serves is the primary card, and the SPC in slot 9 is the secondary card. Each SPC has a specialized central processing unit (CPU) and 1GB of random access memory (RAM).
There are two PC-Card slots on the SPC, each of which accepts ATA Type I or Type II PCMCIA cards, that accommodate removable PC-Cards for temporary storage. These cards can be used to load and store configuration data, software updates, buffer accounting information, and store diagnostic or troubleshooting information.
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Card Ejector Levers - Use to insert/remove card to/from chassis.
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Interlock Switch —When pulled downward, the interlock switch notifies the system to safely power down card prior to removal.
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Card Level Status LEDs —Show the status of the card. (See Hardware Installation Guide for definitions).
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System Alarm Speaker —Sounds an audible alarm when specific system failures occur.
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System Level Status LEDs —Show the status of overall system health and/or maintenance requirements. (See Hardware Installation Guide for definitions).
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Alarm Cut-Off (ACO)—Press and release this recessed toggle switch to reset the system alarm speaker and other audible or visual alarm indicators connected to the CO alarm interface on the SPIO.
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Dual PC-Card/PCMCIA Slots—Stores or moves software, diagnostics, and other information.
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The PAC provides the packet processing and forwarding within the ST16 hardware platform and used with Switch Processor Cards (SPCs). Each PAC can support multiple contexts, which allows you to overlap or assign duplicate IP address ranges in different contexts. PACs are available with either 4 GB or 8GB of memory.
Specialized hardware engines are deployed to support parallel distributed processing for compression, classification, traffic scheduling, forwarding, packet filtering, and statistics.
The PAC is also available with an optional Encryption Daughter Card (EDC). The EDC permits hardware-based IPSec encryption for faster processing of encrypted data packets.
Each PAC has four control processor (CP) subsystems where the bulk of the packet-based user service processing is done. On 4GB PACs, each CP subsystem has a high-speed CPU and one gigabyte of local memory. On 8GB PACs, each CP subsystem has a high-speed CPU and two gigabytes of local memory. A fully configured system, utilizing 14 4GB PACs, has 56 control processors, each with 1GB RAM (total 56 GB RAM) dedicated to packet processing tasks. A fully configured system, utilizing 14 8GB PACs, has 56 control processors, each with 2GB RAM (total 112GB RAM) dedicated to packet processing tasks.
To take advantage of the distributed processing capabilities of the system, you can add additional PACs to the chassis without their supporting line cards, if desired. This results in increased packet handling and control transaction processing capabilities. Another advantage is a decrease in CPU utilization when the system performs processor-intensive tasks such as encryption or data compression.
Install PACs in chassis slots 1 through 7 and 10 through 16. Each installed PAC can either be allocated as active, available to the system for session processing, or redundant, a standby component available in the event of a failure.
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Card Ejector Levers - Use to insert/remove card to/from chassis.
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Interlock Switch - When pulled downward, the interlock switch notifies the system to safely power down card prior to removal.
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Card Level Status LEDs - Show the status of the card. (See Hardware Installation Guide for definitions)
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The Switch Processor I/O (SPIO) card provides connectivity for local and remote management, CO alarming, and BITS timing input. SPIOs are installed in chassis slots 24 and 25, behind SPCs. During normal operation, the SPIO in slot 24 works with the active SPC in slot 8. The SPIO in slot 25 serves as a redundant component. In the event that the SPC in slot 8 fails, the redundant SPC in slot 9 becomes active and works with the SPIO in slot 24. If the SPIO in slot 24 should fail, the redundant SPIO in slot 25 takes over.
The following shows the panel of the SPIO card, its interfaces, and other major components.
SPIO management LAN interfaces connect the system to the carrier’s management network and subsequent applications, normally located remotely in a Network Operations Center (NOC). You can use the RJ-45 10/100/1000 Mbps Ethernet interfaces or optical SFP Gigabit Ethernet interfaces.
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Fiber, LC duplex female connector
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Fiber Type: Multi-mode fiber (MMF), 850 nm wavelength
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The console uses an RS-232 serial communications port to provide local management access to the command line interface (CLI). A 9-pin-to-RJ-45 console cable is supplied with each SPIO card. The console cable must provide carrier-detect when attached in a null modem configuration.
Should connection to a terminal server or other device requiring a 25-pin D-subminiature connector be required, a specialized cable can be constructed to support DB-25 to RJ-45 connectivity. Refer to the
Technical Specifications chapter later in this document for the pin-outs for this cable. The baud rate for this interface is configurable between
9600 bps and 115,200 bps (default is 9600 bps).
A Building Integrated Timing Supply (BITS) module is available on two versions of the SPIO: one supports a BITS BNC interface and the other a BITS 3-pin interface. If your system uses the optical and/or channelized line cards (for SDH/SONET), you can configure it to have the SPIO’s BITS module provide the transmit timing source, compliant with Stratum 3 requirements, for all the line cards in the chassis.
The CO alarm interface is a 10-pin connector for up to three dry-contact relay switches to trigger external alarms, such as lights, sirens or horns, for bay, rack, or CO premise alarm situations. The three Normally Closed alarm relays can be wired to support Normally Open or Normally Closed devices, indicating minor, major, and critical alarms. Pin-outs and a sample wiring diagram for this interface are shown in
Technical Specifications chapter, later in this guide.
A CO alarm cable is shipped with the product so you can connect the CO Alarm interfaces on the SPIO card to your alarming devices. The “Y” cable design ensures CO alarm redundancy by connecting to both primary and secondary SPIO cards.
The RCC uses 5 Gbps serial links to ensure connectivity between rear-mounted line cards and every non-SPC front-loaded application card slot in the system. This creates a high availability architecture that minimizes data loss and ensures session integrity. If a PAC were to experience a failure, IP traffic would be redirected to and from the LC to the redundant PAC in another slot. Each RCC connects up to 14 line cards and 14 PACs for a total of 28 bi-directional links or 56 serial 2.5 Gbps bi-directional serial paths.
The RCC provides each PAC with a full-duplex 5 Gbps link to 14 (of the maximum 28) line cards placed in the chassis. This means that each RCC is effectively a 70 Gbps full-duplex crossbar fabric
, giving the two RCC configuration (for maximum failover protection) a 140 Gbps full-duplex redundancy capability.
The RCC located in slot 40 supports line cards in slots 17 through 23 and 26 through 32 (upper rear slots). The RCC in slot 41 supports line cards in slots 33 through 39 and 42 through 48 (lower rear slots):
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Card Ejector Levers—Use to insert/remove a card to and from the chassis.
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Interlock Switch—When pulled downward, the interlock switch notifies the system to safely power down card prior to removal.
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Card Level Status LEDs—Show the status of the card. (See Hardware Installation Guide for definitions).
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The Ethernet 10/100 line card, commonly referred to as the Fast Ethernet Line Card (FELC), is installed directly behind its respective PAC, providing network connectivity to the RAN interface and the packet data network. Each card has eight RJ-45 interfaces, numbered top to bottom from 1 to 8. Each of these IEEE 802.3-compliant interfaces supports auto-sensing 10/100 Mbps Ethernet. Allowable cabling includes:
The Ethernet 10/100 Line Card can be installed in chassis slots 17 through 23, 26 through 39, and 42 through 48. These cards are always installed directly behind their respective PACs, but are not required to be placed behind any redundant PACs (those operating in Standby mode).
The following shows the panel of the Ethernet 10/100 line card, identifying its interfaces and major components:
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Card Ejector Levers—Use to insert/remove card to/from chassis.
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Interlock Switch—When pulled downward, the interlock switch notifies the system to safely power down card prior to removal.
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Card Level Status LEDs—Show the status of the card. (See Hardware Installation Guide for definitions).
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RJ-45 10/100 Ethernet Interfaces—Eight auto-sensing RJ-45 interfaces for R-P interface connectivity, carrying user data. Ports are numbered 1 through 8 from top to bottom.
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The Ethernet 1000 line card is commonly referred to as the GigE or Gigabit Ethernet Line Card (GELC). The Ethernet 1000 line card is installed directly behind its respective PAC, providing network connectivity to the packet data network. The type of interfaces for the Ethernet 1000 line cards is dictated by the Small Form-factor Pluggable (SFP) module installed as described below:

IMPORTANT:
Class 1 Laser Compliance NoticeThis product has been tested and found to comply with the limits for Class 1 laser devices for IEC825, EN60825, and 21CFR1040 specifications.
The Ethernet 1000 Line Cards can be installed in chassis slots 17 through 23, 26 through 39, and 42 through 48. These cards are always installed directly behind their respective PACs, but they are not required behind any redundant PACs (those operating in Standby mode).
Each card has a switched interlock mechanism that is integrated with the upper card ejector lever. This ensures proper notification to the system before a card is removed. You cannot configure or place a card into service until you push the card interlock switch upward. This locks the upper ejector lever in place and signals the system that the card is ready for use.
When you pull the interlock downward, it allows the upper ejector lever to be operated. This sliding lock mechanism provides notification to the system before you physically remove a card from the chassis. This allows the system time to migrate various processes on the particular operational card.The upper card ejector only operates when the slide lock is pulled downward to the unlocked position.