Data streams in end-to-end communications can cross multiple network domains in which different QoS solutions are deployed. The provision of end-to-end quality of service over heterogeneous environment assumes the negotiation of mutually acceptable SLA. The negotiation process gives the user the ability to specify the desired level of service, along with the permissible pricing of the service. This paper presents the use of COPS-SLS protocol for the negotiation of intra-, inter-domain and end-to-end QoS.