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    Redundant SFMs Overview

    Inspect redundant SFMs to ensure that all traffic leaving the Flexible PIC Concentrators (FPCs) is handled properly.

    SFMs are control boards that handle traffic transiting the router. The SFMs provide route lookup, filtering, and switching. (See Figure 1.)

    Up to four interconnected SFMs can be installed in the M160 router, providing a total of 160 million packets per second (Mpps) of forwarding. Up to two SFMs can be installed in the M40e router. Each SFM can process 40 Mpps.

    The SFM is a two-board system containing the Switch Plane Processor (SPP) card and the Switch Plane Router (SPR) card. When the serial stream of bits leaves the FPC, it is directed to one of the SFMs. The Distributed Buffer Manager ASIC on the SFM distributes the data cells throughout memory banks that are shared over all FPCs. The Internet Processor II ASIC on the SFM performs route lookups and makes forwarding decisions. The Internet Processor II ASIC notifies a second Distributed Buffer Manager ASIC SFM, which forwards the notifications to the outbound interface. Each SFM effectively handles from one-half to one-quarter of the traffic on each FPC.

    The SFMs are hot-removable and hot-insertable. Inserting or removing an SFM causes a brief interruption in forwarding performance (about 500 ms) as the Packet Forwarding Engine reconfigures the distribution of packets across the remaining SFMs.

    Figure 1: M40e and M160 Router SFM Location

    M40e and M160 Router
SFM Location

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    Published: 2012-08-20