Role of the RPC detector in the CMS muon system for tracking and trigger

The Resistive Plate Chambers are used in CMS as dedicated muon trigger detector both in the barrel and in the two endcap regions. They also contribute to muon reconstruction and identification with Drift Tube in the barrel and Cathode Strip Chambers in the endcaps. About 3000 square meter of double gap RPCs have been produced and installed in the experiment since 2007. The performance study and operational experience after three years of successful data taking at LHC is presented. Preliminary estimate of efficiency improvement of muon identification by the upgrade for the next two years is also shown.