This read-only counter tracks the number of input PDUs for which this entity was not the intended final destination and for which it attempted to forward the packet onward. An admin uses this as the core measure of how much transit traffic a device configured as an intermediate system is actually routing, as opposed to traffic destined for itself. For example, a router showing this counter growing in lockstep with overall network traffic growth confirms it is actively forwarding CLNP packets rather than sitting idle.