a communication network used to link information handling systems together utilizes a switching network to transmit data among senders and receivers . each individual packet of data is described and controlled by an fcb . the bandwidth associated with the storing and distribution of data is optimized by chaining the data packets in different types of queues , or operating without chaining outside a queue . when a frame is in an output queue , the third word contains an rfcba for egress of the frame to a line port , and an mcid for ingress from an output queue to a switch port . the rfcba and the mcid have multicast capabilities . the format does not require a third word when a frame is in an input queue .