Understanding M160 Router Redundant SFM Operation

Up to four SFMs can be installed into the midplane from the rear of the M160 router chassis, as shown in Figure 229. All SFMs are active at the same time. A failure or taking an SFM offline has no effect on router function unless it is the only SFM installed. If only one SFM is installed, forwarding halts until the SFM is replaced and is back online. If two or more SFMs are installed, forwarding continues uninterrupted.