This paper describes a novel adaptive clock recovery method that uses proportional-integral-derivative (PID) control. The adaptive clock method is a clock recovery technique that synchronizes connected terminals via packet networks, and will be indispensable for circuit emulation services in the next generation Ethernet. Our adaptive clock method simultaneously achieves a short starting-time, accuracy, stable recovery clock frequency, and few buffer delays using the PID control technique. We explain the numerical simulations, experimental results, and circuit designs.

The Ethernet network is widely used and adopted to the access portion or metro area for the reason of new applications for native Ethernet services or its economical advantage. Apart from these applications for native Ethernet, an encapsulation technology to transport legacy services over Ethernet, i.e. TDM over Ethernet, is focused on. In order to apply it to the carrier networks, it is necessary to meet Quality of Service (QoS) requirements, and the consideration of operation, administration and maintenance (OAM) aspects are indispensable. Furthermore, in order for higher reliability, it is required to apply protection function to the networks. We have studied the encapsulation method of TDM signals applied to circuit emulator accommodating TDM signals over Ethernet. In addition, the OAM mechanism and the protection function are studied. This paper shows the frame format, the detail of the OAM mechanism and the protection function, and introduces a developed circuit for adaptation of TDM over Ethernet.

In this paper we present two traffic control approaches, a circuit emulation traffic control (CETC) and an adaptive priority traffic control (APTC) for supporting voice services in ATM networks. Most voice services can be handled as CBR traffic, this causes a lot of wasted bandwidth. Sending voice through VBR (variable bit rate) may be a better alternative, because it allows the network to allocate voice bandwidth on demand. In CETC, the service discipline guarantees the quality of service (QOS) for voice circuits. Through mathematical analysis, we show that CETC features an adequate performance in delay-jitter. Moreover, it is feasible in implementation. We also present an APTC approach which uses a dynamic buffer allocation scheme to adjust the buffer size based on the real traffic need, as well as employs an adaptive priority queuing technique to handle various delay requirements for VBR voice traffic. It provides an adequate QOS for voice circuits in addition to improving the multiplexing gain. Simulation results show that voice traffic get satisfied delay performance using our approaches. It may fulfill the emerging needs of voice service over ATM networks.

A circuit emulation technique in the ATM network becomes necessary to guarantee user requirements similar to QOS grade offered by STM network where small bit error rates and constant delay times are offered. The Head-Of-Line method or other priority control schemes may be considered to provide such service in the ATM network, while it is known to give too inferior quality to non-circuit emulation service traffic. In this paper, we propose a new method called a periodical bandwidth allocation method for the circuit emulation technique. The cells of circuit emulation service traffic are transmitted periodically in our proposal. A periodical interval is determined from both the length of limit delay time of circuit emulation traffic in each switching node and the number of cell arrivals during the limit delay time. To evaluate our method, we consider three kinds of arrival patterns (the best case, the moderate case, and the worst case) for the circuit emulation traffic and a two-state MMPP for modeling the non-circuit emulation traffic. We show performance results in terms of the cell loss probability and the mean delay time in our proposal through analytic and simulation approaches.