Circuit emulation service (CES) is a telecommunication technology used to send information over asynchronous data networks like ATM, Ethernet or MPLS, so that it is received error-free with constant delay, similar to a leased line. CES was introduced for ATM networks. As the interest for ATM is declining, most new applications work over packet-based (IP)-networks. Two commonly used protocols are SAToP (IETF RFC 4553) and CESoPSN (IETF RFC 5086).