two main processes are performed demultiplexing of contiguous bytes of payload on each member and generating control packet information for each member the standards describe what needs to be done but not how to do it according to the presently preferred embodiment of the invention these two functions are performed in two different blocks the transmit payload demultiplexing tpd block 30 and the transmit control packet generation tcpg block 32 in order to implement lcas these blocks have to be able to work with a dynamic members allocation in order to provide that functionality the present invention utilizes a third block the configuration update block 34 as illustrated in fig7 the configuration update block 34 receives input from the status block 14 and provides output to the tpd block 30 and the tcpg block 32 fig8 illustrates the timing for this transaction member allocation in lcas can only be updated at transition between two multiframes this means that the configuration produced by lcas processing 16 stored in status block 14 cannot be used directly but has to be updated at a precise time the mapper not shown gives time reference for the multiframe boundaries the member allocation update process is performed independently for each vcg by a finite state machine in the configuration update block 34 that is responsible for extracting the new configuration information from lcas status registers control packets sent by tcpg block 32 contain the configuration that will be used for payload transport during the next multiframe this means that two different configurations have to be maintained one for.