Considering ever increasing importance of traffic sharing am- ong the users connected with different Optical Network Units (ONUs) of a TDM-Passive Optical Network (TDM-PON), to date, different TDM-PON architectures have been introduced. These architectures facilitate traffic flow among the ONUs directly along with traffic flow between an ONU and the Optical Line Terminal (OLT), which is the centralized intelligence of a TDM-PON system. The TDM-PON that facilitates direct communication among different ONUs under a single TDM-PON system is namely called TDM-PON Internetworking architecture. In this paper, we come up with a novel operational mechanism for one of the well-known TDM-PON Internetworking architectures in order to improve energy saving performance. An ONU in the TDM-PON Internetworking architecture based on which we propose a novel Internetworking operational mechanism can have two modes: LAN-PON (sharing traffic with other ONUs directly without any assist from the OLT) and broadband access (facilitates OLT and ONU communication). In order to facilitate operating under these two modes, an ONU uses two low-cost Optical Switches (OSWs). We refer to this Internetworking architecture as OSW based solution. Our novel energy efficient operational mechanism allows an ONU in OSW based solution to use Energy Saving Mode (ESM). The simulation results state that the operational mechanism introduced in this paper can contribute in increasing energy saving performance of ONUs noticeably.