Its local completion-data reservation can be exhausted. Tags, link credits and destination storage are separate admission resources.

Common trap: Giving a generic fix without identifying the boundary and unmet obligation in this example.

They advertise receiver header/data buffering for Posted, Non-Posted and Completion traffic in a virtual channel. A transmitter may send a TLP only when the required credit units are available; the six accounting classes are not one count of arbitrary TLPs. Lack of a required credit backpressures that traffic until an update or other specified event.

Common trap: Confusing credits with link width.