Protocol Control Information

In telecommunication, the term protocol-control information or PCI has the following meanings: 1. The queries and replies among communications equipment to determine the respective capabilities of each end of the communications link. 2. For layered systems, information exchanged between entities of a given layer, via the service provided by the next lower layer, to coordinate their joint operation.
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1. The queries and replies among communications equipment to determine the respective capabilities of each end of the communications link. 2. For layered systems, information exchanged between entities of a given layer, via the service provided by the next lower layer, to coordinate their joint operation.