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This chapter provides an overview of the Cisco XR 12404 router. It contains physical descriptions of the router hardware and major components, and functional descriptions of hardware-related features.
The Cisco XR 12404 router scales the Internet Service Provider edge from speeds of T3/E3 (44.7/34.4 Mbps) up to OC-192/STM-64 or 10GE (10 Gbps).
Figure 1-1 shows the PRP-2, consolidated switch fabric (CSF) card, and line card locations of the Cisco XR 12404 router. Network interfaces reside on the line cards that provide the connection between the router's CSF and the external networks. The bottom slot (labeled Fabric Alarm) is a dedicated slot for the combined CSF card.
Note Illustration is shown without the front door for clarity.
Figure 1-1 Cisco XR 12404 Router—PRP2 Front View
|
Line card |
|
CSF card |
|
Line card |
|
Rack mounting bracket |
|
Route Processor |
Figure 1-2 Cisco 12404 Router with PRP-3—Front View
The Cisco XR 12404 router supports up to 8 chassis in a one standard 7-foot (2.15 meter) rack and has the following key features:
•Route processor (PRP-2)—The primary route processor is installed in it's own dedicated slot. A redundant route processor can go in any line card slot. See the "Route Processor" section for information.
•Line cards—The card cage contains 4 hot-swappable card slots. The router can accommodate up to three OC-192 line cards (or 2 line cards if redundant route processors are installed). See the "Supported Line Cards" section for information.
•Consolidated switch fabric card (CSF)—Switch fabric, alarm, and clock schedule functions are located on one board. The CSF card has a switching capacity of 10 Gbps. See the "Consolidated Switch Fabric Card" section for information.
•AC power entry module (PEM)—A customized and hot-swappable one-piece unit. See the "Power Entry Modules" section for information.
•DC power entry module (PEM) and DC power distribution unit (PDU)—Two pieces that can be removed as one unit or in separate pieces. See the "Power Entry Modules" section for information.
Note When operating the router, both power module bays must have DC PEMs and DC PDUs installed to ensure EMI compliance.
•Fan tray assembly—Supplies cooling air to the router. See the "Fan Tray Assembly" section for information.
•Cable management bracket used to neatly route line card cables. See the "Cable Management System" section for information.
•Maintenance Bus—Controls all of the MBus modules in the system. See the "Maintenance Bus" section for information.
The route processor for the Cisco XR 12404 router is the Performance Route Processor (PRP-2). For detailed information about the PRP-2, refer to the Cisco document, Performance Route Processor Installation and Configuration Guide.
The PRP-2 and PRP-3 performs the following primary functions:
•Executes routing protocol stacks
•Performs all protocol communications with other routers
•Builds and distributes forwarding information to all line cards
•Uploads the operating system software images to all installed line cards during power-on
•Provides out-of-band system console and auxiliary ports and an Ethernet port for router configuration and maintenance
•Monitors and manages the power and temperature of system components such as line cards, power supplies, and fans
The Cisco PRP-2 and PRP-3 delivers all these functions with enhanced performance and capabilities. It also delivers the following feature enhancements (depending on the software version running):
•2 Ethernet management ports
•Hard-drive support (optional part)
•BITS input ports
•1 GB compact image Flash memory support (optional part)
•Memory scalability up to 4 GB with PRP-2 and up to 8 GB with PRP-3.
The PRP-2 and PRP-3 communicates with the line cards either through the switch fabric or through the MBus. The switch fabric connection is the main data path for routing table distribution as well as for packets that are sent between the line cards and the PRP. The MBus connection allows the PRP-2 and PRP-3 to download a system bootstrap image, collect or load diagnostic information, and perform general, internal system maintenance operations.
The PRP-2 can be designated as either the Designated System Controller (DSC) or the Secure Domain router (SDR).
The Designated System Controller (DSC) performs the following functions:
•Implements control plane operations for the chassis
•Monitors temperature and voltage
•Monitors line cards
•On boot up, the first card to become active is designated as the DSC.
The Secure Domain Router (SDR) controls domain security features independent of any other SDRs on the network.
In addition to the functionality listed for the PRP-2, PRP-3 provides the following specific functions:
•Reduced boot time.
•Increased overall scalability.
•Improved memory access rates and scale.
•Improved CPU performance through dual 1.3-GHz PPC processor cores.
•Improved packet processing using hardware-based acceleration.
•10-G bandwidth backplane connectivity.
•Support for all 124xx and 128xx chassis, except low-speed fabric (2.5 G).
•New ROMMON that supports IPv4 network configuration directly.
The performance route processor (PRP-2) uses a Motorola PowerPC 7457 CPU that runs at an external bus clock speed of 133 MHz and has an internal clock speed of 1.3 GHz.
Figure 1-3 identifies the slots, ports, and LEDs on the PRP front panel.
Figure 1-3 Performance Route Processor-2 (PRP-2) Front Panel
Table 1-1
|
PCMCIA flash disk slots (shown with cover in place) and slot LEDs |
|
Console serial port |
|
RJ-45 Ethernet ports and data status LEDs |
|
Reset button |
|
Auxiliary serial port |
|
Alphanumeric messages |
PRP-2 Front Panel Hardware Components
Figure 1-4 Performance Route Processor 3 (PRP-3) Front Panel
Table 1-2 PRP-3 Front Panel Hardware Components
|
|
---|---|
1 |
Ejecter Lever |
2 |
Handle |
3 |
External Compact Flash |
4 |
Reset button |
5 |
Alphanumeric LEDs |
PRP-3 is the route processor for the Cisco XR 12404 and 12804 Router chassis running Cisco IOS XR Software Release 3.8.0 or a later release. The PRP-3 is available as product number PRP-3 or PRP-3= for a primary route processor and is available as PRP-3/R for a redundant route processor. PRP-3 has significant improvements over PRP-2. These improvements include increased speed, improved scalability, higher system memory, faster packet processing. Because PRP-3 does not support Cisco IOS, the bootflash memory no longer exists in PRP-3. PRP-3 ROMMON has software intelligence to download a Cisco IOS XR image without the support of bootflash memory.
Note PRP-3 supports Cisco XR 12404 (10 G per slot fabric) and Cisco XR 12804 (40 G per slot fabric) Router chassis only. PRP-3 does not support Cisco XR 12004, 12006, 12010, and 12016 Router chassis (2.5 G low-speed fabric).
Two PCMCIA card slots (slot 0 and slot 1) provide the PRP with additional flash memory capacity. All combinations of different flash devices are supported by the PRP. You can use ATA flash disks, Type 1 or Type 2 linear flash memory cards, or a combination of the two.
Note The PRP only supports +5.2 VDC flash memory devices. It does not support +3.3 VDC PCMCIA devices.
Status LEDs (Slot-0 / Slot-1) indicate when the flash memory card in that slot is accessed (see Figure 1-3). Each slot has an eject button (located behind the cover) to remove a flash card from the slot.
Note PRP-3 does not have PCMCIA slots (slot 0 and slot 1). PRP-3 has an external CompactFlash (disk0:) that replaces the PCMCIA slots.
The PRP has two 8-pin media-dependent interface (MDI) RJ-45 ports for either IEEE 802.3 10BASE-T (10 Mbps) or IEEE 802.3u 100BASE-TX (100 Mbps) Ethernet connections. These ports are labeled ETH 0 and ETH 1.
The transmission speed of the Ethernet port is not user-configurable. You set the speed through an autosensing scheme on the PRP which is determined by the network that the Ethernet port is connected to. However, even at an autosensed data transmission rate of 100 Mbps, the Ethernet port can only provide a usable bandwidth of substantially less than 100 Mbps. You can expect a maximum usable bandwidth of approximately 20 Mbps when using an Ethernet connection.
The following LEDs on the front panel indicate traffic status and port selection (Figure 1-5):
•LINK, EN, TX, RX—Indicate link activity (LINK), port enabled (EN), data transmission (TX), and data reception (RX).
•PRIMARY—Indicates which Ethernet port is selected (ETH 0 or ETH 1).
Note Because both ports are supported on the PRP, ETH 0 is always on. ETH 1 lights when it is selected.
Figure 1-5 PRP-2 Port Activity LEDs—Partial Front Panel
Figure 1-6 PRP-3 Port Activity LEDs—Partial Front Panel
The auxiliary and console ports on the PRP are EIA/TIA-232 (also known as RS-232) asynchronous serial ports. These ports connect external devices to monitor and manage the system.
•The auxiliary port—A (male) plug that provides a data terminal equipment (DTE) interface. The auxiliary port supports flow control and is often used to connect a modem, a channel service unit (CSU), or other optional equipment for Telnet management.
•The console port—A (female) receptacle that provides a data circuit-terminating equipment (DCE) interface for connecting a console terminal.
The PRP-3 has the following LED indicators:
•Two Ethernet port LEDs used in conjunction with each of the three RJ-45 Ethernet connectors:
–LINK—Indicates link activity
–DATA—Indicates data transmission or reception
•Two BITS port LEDs used in conjunction with each of the two BITS ports:
–SIG—Indicates carrier signal available
–ACT—Indicates that the interface is active
Note BITS feature is not supported in Release 3.8.0.
•One auxiliary port (AUX) and one console port (CONSOLE) LED:
–AUX—Used as a backup for the command outputs on the Console.
–CONSOLE—Used for configuring the router by connecting an RJ-45 cable to the console terminal. The router can be configured through the console terminal.
Access to the (soft) reset switch is through a small opening in the PRP front panel (see Figure 1-3). To press the switch, insert a paper clip or similar small pointed object into the opening.
Pressing the reset switch causes a nonmaskable interrupt (NMI) and places the PRP in ROM monitor mode. When the PRP enters ROM monitor mode, its behavior depends on the setting of the PRP software configuration register. For example, if the boot field of the software configuration register is set to:
•0x0—The PRP remains at the ROM monitor prompt (rommon>) and waits for a user command to boot the system manually.
•0x1—The system automatically boots the first Cisco IOS image found in flash memory on the PRP.
The alphanumeric message displays are organized in two rows of four LED characters each (Figure 1-7).
Figure 1-7 Alphanumeric Message Displays—Partial Front Panel
The alphanumeric message displays show router status messages during the boot process, and after the boot process is complete.
•During the boot process, the message displays are controlled directly by the MBus module.
•After the boot process, the message displays are controlled by Cisco IOS XR software (through the MBus).
The alphanumeric message displays also provide information about different levels of system operation, including the status of the PRP, router error messages, and user-defined status and error messages
Note A list of all system and error messages appears in the Cisco IOS System Error Messages publication.
This section describes various types of memory used on the PRP to support router functions. Table 1-3 provides a quick reference of the different types of memory, and Figure 1-8 shows the location on the PRP board.
|
|
|
|
|
---|---|---|---|---|
SDRAM1 |
2 GB (default) or 4 GB (optional) |
1 or 2 |
2-GB or 4-GB DIMMs (based on desired SDRAM configuration) for main Cisco IOS XR software functions |
U15 (bank 1)2 |
SRAM3 |
2 MB (fixed) |
— |
Secondary CPU cache memory functions |
— |
NVRAM4 |
2 MB (fixed) |
1 |
System configuration files, register settings, and logs |
— |
HDD |
40 GB |
1 |
Contains log and crash information for specific Cisco IOS XR versions. |
— |
Flash memory |
2 GB or 4 GB (optional) Compact Flash |
1 |
Contains Cisco IOS XR boot image (bootflash), crash information, and other user-defined files |
P3 |
4 MB Boot ROM |
1 |
Stores the ROMMON minimum boot image (MBI). |
— |
|
Flash disks5 2 GB (default) or 4 GB (optional) |
1 or 2 |
Contains Cisco IOS XR software images, system configuration files, and other user-defined files on up to two flash disks |
Flash disk |
|
1 GB CF6 |
1 |
Contains large Cisco IOS XR software images |
— |
1 Default SDRAM configuration is 2-GB for PRP-2. Bank 1 (U15) must be populated first. You can use one or both banks to configure SDRAM combinations of 2 GB and 4 GB for the PRP-2. 1.5-GB configurations.and DIMM devices that are not from Cisco are not supported. 2 If both banks of the PRP-2 are populated, bank 1 and bank 2 must contain the same size DIMM. 3 SRAM is not user configurable or field replaceable. 4 NVRAM is not user configurable or field replaceable. 5 ATA Flash disks are supported in the PRP-2. 6 Optional PRP-2 hardware. Compact disks that are not from Cisco are not supported. |
Figure 1-8 PRP-2 Memory Locations
Figure 1-9 PRP-3 Memory Locations
|
SDRAM DIMM: Bank 1 - Socket number U8 |
|
SDRAM DIMM: Bank 2 - Socket number U10 |
|
External CompactFlash |
|
Hard disk (80 GB) |
|
Internal CompactFlash |
|
|
|
|
|
---|---|---|---|---|
SDRAM1 |
2 GB (Default) for each DDR2 DRAM for a total system memory of 4 GB, option for upgrade to total system memory of 8 GB (4 GB each). |
2 |
Two 2-GB default DDR2 DRAM for main CiscoIOSXR software functions. Provision for optional upgrade to 4 GB also possible to provide total system memory of 8 GB. |
U8 (bank 1)2 |
NVRAM3 |
2 MB (fixed) |
1 |
System configuration files, register settings, and logs |
— |
Flash memory |
2 GB (default) or 4 GB (optional) Flash disks4 |
2 (Internal and External CompactFlash) |
Contains Cisco IOS XR software images, system configuration files, and other user-defined files on two CompactFlash. |
Internal and External Compact Flash5 |
Flash boot ROM |
8 MB |
1 |
Flash EPROM for the ROM monitor program boot image |
— |
HDD6 |
80 GB SATA |
1 |
Contains log and crash information for specific Cisco IOS XR versions |
— |
1 Default SDRAM configuration is a total of 4 GB (2 x 2GB) system memory for PRP-3. Bank 1 (U15) must be populated first. You can use one or both banks to configure DDR2 DRAM combinations of 2 GB or 4 GB for the PRP-3. DIMM devices that are not from Cisco are not supported. 2 If both banks of the PRP-3 are populated, bank 1 and bank 2 must contain the same size DIMM. 3 NVRAM is not user configurable or field replaceable. 4 ATA Flash disks are supported in the PRP-3. 5 PRP-3 provides an onboard internal CompactFlash and also an external CompactFlash. The external CompactFlash in PRP-3 replaces the two PCMCIA slots (slot0 and slot1) of PRP-2. 6 Hard disk drives that are not from Cisco are not supported. |
The PRP uses Error Checking and Correction (ECC) Synchronized Dynamic Random Access Memory (SDRAM) to store routing tables, protocols, network accounting applications, and to run Cisco IOS software.
Table 1-5 lists the DRAM configurations for the PRP. If you are using:
•One DIMM—Bank 1 (U15) must be populated first.
•Two DIMMs—You cannot mix memory sizes; both banks must contain the same size DIMM.
|
|
|
---|---|---|
|
|
|
2 GB1 |
U15 (bank 1) |
One 2 GB DIMM |
4 GB |
U15 (bank 1) |
One 4 GB DIMM |
1 Default shipping configuration. |
PRP-3 provides more system memory than PRP-2. PRP-3 is shipped with 2 GB of system memory in each DDR2 DRAMs, for a total of 4 GB and provides an upgrade option for a total of 8 GB (4 GB x 2 DRAM).
Note The two DIMMs must be of the same sizes. Do not use two different DIMM sizes together.
Table 1-6 PRP3 DDR2 DRAM Configuration
|
|
|
---|---|---|
4 GB |
U8 (bank 1) |
Two 2 GB DIMMs |
8 GB |
U8 (bank 1) |
Two 4 GB DIMMs |
Static Random Access Memory (SRAM) provides 2 MB of secondary CPU cache memory. Its principal function is to act as a staging area for routing table updates, and for information sent to and received from the line cards. SRAM is not user-configurable and cannot be upgraded in the field.
Non-volatile Random Access Memory (NVRAM) provides 2 MB of memory for system configuration files, software register settings, and environmental monitoring logs. Built-in lithium batteries retain the contents of NVRAM for a minimum of 5 years. NVRAM is not user configurable and cannot be upgraded in the field.
Use flash memory to store multiple Cisco IOS XR software and microcode images that you can use to operate the router. You can download new images to flash memory over the network (or from a local server) to replace an existing image, or to add it as an additional image. The router can be booted (manually or automatically) from any of the stored images in flash memory.
Flash memory also functions as a Trivial File Transfer Protocol (TFTP) server to allow other servers to boot remotely from the stored images, or to copy them into their own flash memory.
The system uses two types of flash memory on PRP-2:
•Onboard flash memory (called bootflash)—Contains the Cisco IOS boot image
•Flash memory disks (or cards)—Contain the Cisco IOS software image
Table 1-7 lists supported flash disk sizes and Cisco part numbers.
|
|
---|---|
2 GB2 |
MEM-FD2G= |
4 GB |
MEM-FD4G= |
1 4 GB is supported with 2 GB mode prior to Release 3.8.0. 2 Default shipping configuration. |
PRP-3 provides more flash memory than PRP-2. PRP-3 uses flash memory to store Cisco IOS XR software images. PRP-3 includes a default internal flash memory of 2 GB and also has an external flash memory of 2 GB. A flash memory upgrade option is also available for a total of 8 GB (2 x 4 GB).
PRP-2 and PRP-3 compactflashes are not compatible with each other and hence PRP-2 compactflash cannot be used in PRP-3 and vice versa. PRP-3 uses Multiword DMA to access the compactflash device, a PRP-2 compactflash does not support this access type.
Note The PRP-3 external CompactFlash disk replaces the two PCMCIA slots of PRP-2. The external CompactFlash disk can be installed or removed from the PRP-3 front panel. The internal CompactFlash disk memory is denoted as compactflash, while the external CompactFlash disk is denoted as disk0:.
Table 1-8 PRP-3 CompactFlash Disk Sizes
|
|
---|---|
2 GB |
FLASH-PRP3-2G(=) |
4 GB |
FLASH-PRP3-4G(=) |
The Cisco XR 12404 router is shipped with up to three installed line cards and one route processor that provide a variety of network media types. Line card slots and route processors shipped from the factory are based on your order. Figure 1-10 shows the card cage slot locations:
•Line cards can be installed in slots 1 through 3 in the card cage.
•Slot zero (0) is the default slot for the primary route processor.
•The bottom slot is reserved for the consolidated switch fabric (CSF) card.
Note Refer to the software release notes for a current list of supported line cards (see the "Obtaining Documentation and Submitting a Service Request" section on page -x).
Figure 1-10 Card Slot Locations
The line cards interface to each other, and to the route processor through the CSF card. Line cards installed in the Cisco XR 12404 router are hot swappable and can be replaced while the router is operating.
Figure 1-11 shows examples of single-mode and multimode line cards.
Figure 1-11 Sample Line Cards
The Cisco XR 12404 router CSF card contains the following functionality:
•Alarm notification and power source monitoring
•Switch fabric synchronized speed interconnections
•Clock and scheduler synchronization signaling
The CSF card alarm functionality provides visual alarm notification of a fault condition. The alarm card function indicates the following condition.
•Alarm status
•CSF MBus
•Alarm MBus status
•Fan fault monitoring
•AC or DC power source status
•DC PEM status
–The 5V MBus power supply has been integrated onto the CSF permitting the use of generic PEMs in the chassis. The Cisco XR 12404 router can monitor for the PEM for these conditions:
•The operational status
•Output voltage
•Output current.
•Alarm Output Function
–The alarm output function is controlled by the software on the route processor. When a signal is received from the route processor the alarm MBus module on the CSF card activates specific LEDs to signal a condition that is critical, major, or minor.
•LEDs
–LEDs alert you to a condition in the router. The determination of a critical, major, or minor alarm condition is designed into Cisco IOS XR software running on your route processor.
•CSF MBus Status
–Drivers are provided for MBus OK and Fail indication.
•The 5V MBus power supply
–Consists of a 100 W DC-DC converter.
•Alarm Status
–The Alarm output function consists of a group of LEDs and their associated drivers connected to an output port on the alarm MBus module. As directed by the software on the route processor, the alarm MBus module on the CSF card activates specific LEDs. The software which drives these LEDs divides them into three levels, Critical, Major, and Minor. The classification of a critical, major, or minor alarm is determined by Cisco IOS XR software running on the route processor. Each of the three LEDs is a dual LED (for failure redundancy).
–The OK/Fail pair of LEDs indicate the status of the alarm MBus:
Green indicates that the alarm MBus module is operating properly.
Amber Fail indicates that the alarm MBus has detected an error in itself or with the MBus module.
The alarm MBus monitors the power supply and signals when there is a condition outside the normal range of operation.
•Power source voltage is not being provided to a component
•A fault exist in the power source or PEM
•A voltage monitor signal is outside the allowable range
•The current monitor signal is outside the allowable range
Switch fabric circuitry provides up to 40 Gbps (full duplex) of synchronized speed interconnections that carries user traffic between line cards or between the route processor and the line cards.
The fabric card generates and distributes system-wide clock and cell time synchronization signaling. System clock generation is delivered to the system through the backplane and local clock functions are derived from the system clock.
•System Clock—The system clock synchronizes data transfers between line cards or between the route processor and a line card through the CSF. The system clock signal is sent to all line cards and the route processor.
•Scheduler—The scheduler handles requests from the line cards for access to the CSF. When the scheduler receives a request from a line card for CSF access, the scheduler determines when to allow the line card access to the CSF.
The Cisco XR 12404 router chassis supports two hot swappable AC or DC PEMs. The router must be populated with 2 PEMs to meet EMI standards.
Each AC PEM converts 200 to 240 VAC into -48 VDC, which is distributed through the chassis backplane to all cards, RPs, and the fan assembly.
Figure 1-12 identifies the components of an AC power supply.
Figure 1-12 AC PEM Components
|
AC PEM finger grips |
|
Power cord receptacle |
|
On/Off switch |
|
Status LEDs |
|
Bail latch |
|
Captive screws |
The status LEDs on the AC PEM provide information about the current operational status of the power supply. Table 1-9 summarizes the function of these indicators.
Each DC PEM operates from a nominal source DC voltage of -48 to -60 VDC and requires a dedicated 35-Amp service.
Figure 1-13 identifies the components of a DC power supply.
Figure 1-13 DC PEM and PDU Components
1 |
DC PDU |
5 |
On/Off switch |
2 |
DC PEM |
6 |
PDU captive screws |
3 |
PEM captive screws |
7 |
PDU terminal block |
4 |
Status LEDs |
The status LEDs on the DC PEM provide information about the current operational status of the power supply. Table 1-10 summarizes the function of these indicators.
The backplane distributes power through the Cisco XR 12404 router and to all cards in the card cage. The PEM converts AC power source into -48 VDC. When directed by the route processor or by MBus software, the MBus module turns on the DC-DC converter; the -48 VDC is converted into +2.5 VDC, +3.3 VDC and +5 VDC for all internal voltages required by the cards.
Power for the fan tray assembly is supplied directly from the backplane. An internal fan tray assembly controller card converts -48 VDC into DC voltage that powers the fans.
The Cisco XR 12404 router is equipped with a fan tray assembly located at the side of the chassis. The fan tray assembly maintains acceptable operating temperatures for the internal components by drawing cooling air across the card cage.
The fan tray assembly is a sheet metal enclosure containing 7 fans and 2 fan controller cards (Figure 1-14).
Warning Exhaust from other equipment vented directly into the Cisco XR 12404 router air inlet can cause an over-heat condition. Install the router so that it is protected from a direct flow of hot air from other equipment.
Figure 1-14 Fan Tray Assembly
The fan tray assembly draws room air in through the air filter, across the card cage and out through exhaust vents located on the side of the chassis.
Note Warm air exits at the side of the chassis. Allow sufficient air flow by maintaining 6 inches (15.24 CM) of clearance at both the inlet and exhaust openings on the chassis.
A fan tray assembly controller card monitors the operation of the 7 fans.
The Cisco XR 12404 router is set up with two types of cable management systems:
•Line card cable-management bracket (Figure 1-15)—Attached to each line card and routes the line card cables to the chassis cable management bracket. These brackets keep the cables free of sharp bends and out of the way.
Figure 1-15 RP and Line Card Cable-Management Brackets
•Chassis cable-management bracket (see Figure 1-16)—Attached to the chassis and routes the line card cables away from the chassis.
Figure 1-16 Chassis Cable Management Bracket
Figure 1-17 Chassis Cable Management Bracket with PRP-3
Cable-management systems:
•Organize the interface cables on the line cards, route processor, and clock and scheduler cards as they enter and exit the system.
•Consists of two parts, a card cable-management bracket and a chassis cable-management bracket.
The Cisco XR 12404 router maintenance bus and MBus modules manage all of the maintenance functions of the system. The MBus consists of two separate busses (providing MBus redundancy). Each MBus is linked to all of the following.
•Line cards
•Route Processor
•CSF card
The MBus module located on each component, communicates over the MBus and is powered by +5 VDC directly from the fabric card. The MBus performs the functions of power-on/off control for each component, component (device) discovery, code download, diagnostics, and environmental monitoring and alarms.
Each MBus module directly controls the DC-to-DC converters on the component it is mounted on based on commands the component receives from its on-board EPROM and from the route processor. Each MBus module is tied directly to +5 VDC from the consolidated fabric card.
When power is applied to the Cisco XR 12404 router, all MBus modules immediately power on. The MBus modules on the route processor and CSF card immediately turn on the DC-to-DC converter, powering up the respective card. The line card MBus module waits to power on the line card until it receives a command from the route processor.
The route processor can determine the system configuration using the MBus. A message is sent from the route processor over the MBus requesting all installed devices to identify themselves. The response back provides component type, line card slot number, and CSF card slot number.
A portion of the line card operating software can be downloaded from the route processor to the line card over the MBus. Because the MBus is relatively slow compared to the CSF, only enough code is downloaded to the line card for it to access the CSF and complete the download process.
The diagnostic software image is downloaded from the route processor to the line card during the test sequence.
The MBus module on each component monitors that component's environment as follows.
•Line cards and the route processor are monitored for temperature by two temperature sensors mounted on each card. The MBus module makes voltage monitoring through software; for example the +2.5 VDC, +3.3 VDC, and +5 VDC DC-to-DC converters.
•The CSF card is monitored for temperature by two temperature sensors mounted on the card. The MBus module performs voltage monitoring through software (for example, the +2.5 VDC and +3.3 VDC).
•Voltage monitoring the for +5 VDC, for example; is made by the alarm MBus module on the CSF card.
•Environmental monitoring includes voltage and current monitoring, temperature monitoring, and sensing for fan power and RPM.