Service Level Agreement (SLA) is one of the common means of communication between customers and service providers through which one of the most important parameters for the customers, connection availability is requested. This paper presents a dynamic service level agreement negotiation mechanism considering intra/inter-domain communications over shared mesh optical networks. The intra-domain negotiation mechanism propagates the link-availability as service level agreement parameters while inter-domain mechanism advertises a proposed service level agreement based traffic engineering constraint called maximum path availability.