This read-write enumerated value (disable/enable/not-applicable/not-available) sets whether the unit's IP router function is active; when enabled, the unit routes IP frames between the different IP networks it's connected to, and when disabled, IP frames are instead bridged (if bridging is enabled) or discarded. An admin toggles this to decide whether the unit performs Layer-3 IP routing across its interfaces or just passes frames through as a bridge. For example, an admin deploying the unit as a simple bridge between two LAN segments would leave ipRouterEnable at disable(1) and rely on bridging instead.