Abstract: An interface device is provided which may be used to perform rate adaptation and time slot assignment, in either the transmit or receive directions, in a multiplexing unit for interfacing a high rate optical carrier line to a plurality of lower rate information carrier lines. The high rate optical carrier line may be a SONET or SDH carrier line. The interface device according to the present invention may be operationally configured to provide data rate adaptation and time slot assignment between an optical carrier line operating at an OC-12 rate with lower rate lines operating according to OC-3, OC-1, DS-3, or DS-1 protocols, or even virtual channels. A plurality of identical interface devices may be cascaded together and used to perform interface support for various channels operating at various rates, merely by manipulating the operational configuration of the individual interface devices in the cascade.

Abstract: A universal tributary interface group approach for SONET multiplex equipment in which the shelf is partitioned into regions and each region can be provisioned to support different service types. The universal tributary group system includes an equipment shelf having a backplane. The equipment shelf is partitioned into regions called tributary groups which are each capable of accepting tributary units having compatible bus widths and clock rates. Removable card guides may be inserted into the tributary group spaces so that tributary interface units of different heights and widths may be placed in the tributary group spaces. Additionally, a plurality of bus segments run along the backplane to electrically connect a time slot interchange unit to card slots in the tributary groups. Each of the bus segments is capable of being provisioned to use a bus rate compatible with the data requirements of the tributary group it services.