This paper deals with the performance evaluation of LAN-Integrated Service protocol called SBM (Subnetwork Bandwidth Manager), a solution to handle QoS requirements over Local Area Networks. SBM is an RSVP-based protocol, which consists in electing a manager over a LAN segment to map RSVP-flows into an appropriate class of service and handles admission control and bandwidth reservation operations for such flows. To show how SBM is useful for guaranteeing requested quality of service for real-time admitted flows, we simulated the bandwidth reservation and message scheduling in an Ethernet switch for different input flows sharing a same output trunk link. DSBM election has also been simulated in order to evaluate time for DSBM failure recovery over switched and shared LAN topology.