Circuit Emulation Service

Circuit Emulation Service ( CES) is a method of data transmission in the time division multiplexed (TDM ) data present on an asynchronous network with packet switching, such as ATM, Ethernet, or any Internet Protocol ( IP) based networks, to be transmitted. Under CES in the narrower sense is sometimes only the transmission over ATM understood (abbreviation also CESoATM ), while the abbreviation CESoP (circuit emulation services over packet ) is most commonly used for transmission over IP.

The method is used for devices of the traditional telephone technology, the digitized speech can thus be transmitted on modern networks. This equipment is therefore a direct wire connection ( "circuit " ), or other transmission path of the TDM signal " fooled " ( emulated), although the data underlying connection works completely differently, namely with data packets that are transmitted over a network.

TDM is a continuous data stream with accurate timing information. By this is converted into CES packets that are then transmitted over, for example, ATM or IP networks. After transmission, the data packets are buffered, composed for TDM signal and transmitted with a fixed clock to the target device. Is a prerequisite for error-free transmission that all data packets arrive in time to be assembled to the TDM signal. Therefore, to be added prior to transmission across the network QoS information in order to achieve a sufficient priority of the transmitted data. Further, the timing of the original TDM signal must be exactly reproduced, so that no data loss occurs due to bit slips.

Wherein the standardized ATM AAL 1 is used for the CES. As a time multiplexed PCM is used almost exclusively with a bit rate of 2.048 Mbit / S.

Due to the rapid development of computer networks and the increasing number of IP networks, the importance of CESoP increases.

• Computer Networks
• Telecommunications