Flexible PIC Concentrators (FPCs)

Flexible PIC Concentrators (FPCs) house the PICs that connect the router to network media (for information about PICs, see Physical Interface Cards (PICs)). The main function of an FPC is to connect the PICs installed in it to the other router components. An I/O Manager ASIC on the FPC divides each incoming data packet into 64-byte cells and passes the cells through the midplane to the SSB, where another ASIC decides how to distribute them among the memory buffers located on and shared by all installed FPCs. After the SSB decides how to forward a packet, an I/O Manager ASIC on the FPC reassembles the corresponding data cells back into network-packet form and passes the packet to the appropriate PIC for transmission to the network. For more information, see Data Flow Through the Packet Forwarding Engine.

The M20 router supports the FPC in Table 9.

Table 9: FPCs Supported by the M20 Router

An Enhanced Plus FPC1 is labeled with an EP sticker on its faceplate.

Enhanced FPCs provide more SRAM memory than the standard FPCs, which increases scalability, provides more granular class-of-service (CoS) capabilities, and enhances VPN scaling.

Up to four FPCs install horizontally into the midplane from the front of the chassis. The FPC slots are numbered top to bottom, from FPC0 to FPC3. Each FPC accommodates up to four PICs. The PIC slots in each FPC are numbered from 0 (zero) through 3, left to right. An FPC can be installed into any FPC slot, regardless of the PICs it contains, and any combination of slots can be used. If a slot is empty, you must install a blank FPC panel to shield it, so that cooling air can circulate properly throughout the card cage.

FPCs are hot-removable and hot-insertable, as described in Field-Replaceable Units (FRUs). When you remove or install an FPC, packet forwarding halts for about 200 ms while the Packet Forwarding Engine adjusts to the change in the amount of memory available in the pool located on and shared by all FPCs. When you install an FPC into a functioning router, the Routing Engine downloads the FPC software, the FPC runs its diagnostics, and the PICs housed on the FPC are enabled. Forwarding continues uninterrupted during this process. For FPC replacement instructions, see Replacing an FPC.

Figure 4 shows a chassis with FPCs installed in all four slots.

Figure 4: Front of Chassis with FPCs Installed

FPC Components

An FPC has the following components:

• FPC card carrier—Houses the ASICs, connectors, and processor subsystem.
• One I/O Manager ASIC—Parses Layer 2 and Layer 3 data and performs encapsulation and segmentation. The ASIC divides incoming packets into 64-byte data cells for easier processing, and reassembles the cells for each packet after the forwarding decision is made for it.
• Two identical synchronous DRAM (SDRAM) dual inline memory modules (DIMMs)—Form the memory pool shared with the other FPCs installed in the router.
• Parity-protected synchronous SRAM (SSRAM)—Stores data structures used by the I/O Manager ASICs.
• Processor subsystem—Manages packet handling in the FPC and communication with the SSB. It is a PowerPC 603e-based CPU with parity-protected DRAM.
• EEPROM—Stores the serial number and revision level of the FPC.
• Two LEDs—Indicate FPC status. The LED labeled OK is green and the one labeled FAIL is amber. The LEDs for each FPC are located on the router craft interface. For more information, see FPC LEDs and Offline Button.
• Offline button—Prepares the FPC for removal from the router when pressed. Like the LEDs, an offline button is located on the craft interface. For more information, see FPC LEDs and Offline Button.
• Ejector levers—Control the locking system that secures the FPC in the card cage.

Note: For specific information about FPC components (for example, the amount of memory available), issue the show chassis fpc command.

FPC Edges

Regardless of whether you are holding an FPC vertically or horizontally, this document uses the same terms for all four edges of the FPC (see Figure 5):

• Faceplate—Edge of the FPC that has slots into which you insert the PICs
• Connector edge—Edge opposite the faceplate; this edge has the connectors that attach to the midplane
• Top edge—Edge at the top of the FPC when it is vertical
• Bottom edge—Edge at the bottom of the FPC when it is vertical

Figure 5: FPC Edges

Handling and Storing FPCs

This section explains how to avoid damaging the FPCs that you install into routing platforms. The instructions in this section apply to all FPCs.

Caution: Many components on the FPC are fragile. Failure to handle FPCs as specified in this document can cause irreparable damage.

Caution: To prevent damage when handling or carrying FPCs, observe the following precautions.

Note: An FPC configured with PICs installed can weigh as much as 7 lb (3.1 kg). Be prepared to accept the full weight of the FPC as you lift it.

As you carry the FPC, do not bump it against anything. FPC components are fragile.

Do not grasp the FPC anywhere except places that this document indicates. In particular, never grasp the connector edge, especially at the power connector in the corner where the connector and bottom edges meet (see Figure 6).

Figure 6: Do Not Grasp the Connector Edge

Do not carry the FPC by the faceplate with only one hand (see Figure 7).

Figure 7: Do Not Carry an FPC with Only One Hand

Do not rest any edge of an FPC directly against a hard surface (see Figure 8). If you must rest the FPC temporarily on an edge while changing its orientation between vertical and horizontal, use your hand as a cushion between the edge and the surface.

Figure 8: Do Not Rest the FPC on an Edge

You hold an FPC horizontally when installing it into the chassis or an equipment rack. To hold an FPC vertically (see Figure 9):

1. Orient the FPC so that the faceplate faces you.
2. Place one hand around the FPC faceplate about a quarter of the way down from the top edge. To avoid deforming the electromagnetic interference (EMI) shielding strip, do not press hard on it.
3. Place your other hand at the bottom edge of the FPC. If the FPC has heat sinks about midway between the faceplate and connector edge, place your other hand against the heat sinks.

Figure 9: Holding an FPC Vertically

If the FPC is horizontal before you grasp it, place your left hand around the faceplate and your right hand along the bottom edge. To hold an FPC horizontally (see Figure 10):

1. Orient the FPC so that the faceplate faces you.
2. Grasp the top edge with your left hand and the bottom edge with your right hand. If the FPC has heat sinks about midway between the faceplate and connector edge, place your right hand against the heat sinks.

You can rest the faceplate of the FPC against your body as you carry it.

Figure 10: Holding an FPC Horizontally

When not installed in the routing platforms, FPCs must be either stored in the container in which a spare FPC is shipped or stored horizontally and component-side up on a flat, stable surface.

When you store an FPC on a horizontal surface or in the shipping container, always place it inside an antistatic bag. Because the FPC is heavy and because antistatic bags are fragile, inserting the FPC into the bag is easier with two people. To do this, one person holds the FPC in the horizontal position with the faceplate facing the body, and the other person slides the opening of the bag over the FPC connector edge. If you must insert the FPC into a bag by yourself, first lay the FPC horizontally on a flat, stable surface, component-side up. Orient the FPC with the faceplate facing you. Carefully insert the FPC connector edge into the opening of the bag, and pull the bag toward you to cover the FPC.

Caution: To prevent damage when storing FPCs, observe the following precautions: Never lay an FPC component-side down. Never stack an FPC under or on top of any other component (see Figure 11).

Figure 11: Do Not Stack FPCs