The present document describes the performance benchmark methology for the IMS based services MMTel@ Video Telephony and IMS - PES. The terminology and concepts are described in TR 101 577 [i.11]. The present document is the first part of the multi-part deliverable which consists of four parts. The present document contains the overall benchmark descriptions@ architectures@ processes@ and information models that are common to all specific benchmarking scenarios. TS 186 008-2 [i.1] contains the specific benchmarking use-cases and scenarios@ along with scenario specific metrics and design objectives. It also defines the SUT configuration parameters. This part also contains any required extensions to the overall descriptions present in the present document@ if necessary for the specific scenario. TS 186 008-3 [i.2] defines an initial benchmark test through the specification of a traffic set@ traffic-time profile and benchmark test procedure. TS 186 008-4 [i.3] defines Reference Load network quality parameters for the use cases defined in TS 186 008-2 [i.1].