Cisco FirePOWER 4100 Series Fail-to-Wire (FTW) Network Module - Fibre Network Module with Bypass - 6 x 10GBase-SR Ports - single-wide module that does NOT support hot swapping - for use with the FirePOWER 4110, 4120, 4140, 4150 series firewalls (FPR4K-NM-6X10SR-F)

The Firepower 4100 contains two network module slots that provide optical or electrical network interfaces. Network modules are optional, removable I/O modules that provide either additional ports or different interface types (1/10/40 Gb). The Firepower network modules plug into the chassis on the front panel.

Hardware bypass (also known as fail-to-wire) is a physical layer (Layer 1) bypass that allows paired interfaces to go into bypass mode so that the hardware forwards packets between these port pairs without software intervention. Hardware bypass provides network connectivity when there are software or hardware failures. Hardware bypass is useful on ports where the Firepower security appliance is only monitoring or logging traffic. The hardware bypass network modules have an optical switch that is capable of connecting the two ports when needed. The hardware bypass network modules have built-in SFPs.