Understanding the SFMs

Purpose

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

What Is an SFM

The SFM is a control board that handles traffic transiting the router (see Figure 144). There are two SFMs on the M40e router and four SFMs on the M160 router (see Figure 145).

Figure 144: SFM Component

The SFMs provide route lookup, filtering, and switching. When the serial stream of bits leaves the FPC, it is directed to one of the SFMs. Each SFM effectively handles one-half or one-quarter of the traffic on each FPC. The SFMs handle a total of 160 million packets per second (Mpps) of forwarding.

Figure 145: M40e and M160 Router SFM Location

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.