The function of the Connection Module Y (CMY) is to connect the filters in two ONS 15252 MCUs. The CMY is, in principle, an extension of the fibers from a Hub Filter module (HFM) module. The CMY connects an A-side filter bank to another A-side filter bank or a B-side filter bank to another B-side filter bank between chassis. The connection permits the extension of the passive optical shelf.The CMY module provides a bridge between the A-side of one ONS 15252 MCU to the A-side of a second ONS 15252 MCU. The CMY also provides a bridge between the B-side of one ONS 15252 MCU to the B-side of a second ONS 15252 MCU.This configuration is needed for systems using more than 16 Client Layer Interface Port (CLIP) modules in the ONS 15252 MCU. The fibers from the CMY to the HFM are coupled straight into a MU duplex connector.