With Ethernet now the de facto standard for networking in any enterprise, customers of Ethernet services can enjoy the ease-of-use benefits that come from long familiarity with Ethernet and apply this knowledge to address their Wide Area Network (WAN) connectivity needs. A number of standards groups, including IEEE, IETF, ITU and MEF, are working to enhance standards for Ethernet services. This paper explains the fundamentals of Carrier Ethernet and examines how service profiles and Service Level Agreements (SLAs) can be defined in Carrier Ethernet.