Time and frequency transfer in an asynchronous TCP/IP over SDH-network utilizing passive listening

A technique for time and frequency transfer over an asynchronous TCP/IP network is being developed by SP, Swedish National Testing and Research Institute together with STUPI. When implemented, users will be able to compare their clocks by connecting to the system. The technique is based on passive listening to existing data traffic in the network. Since the network is asynchronous, intermediate clocks are located and compared at each router. We use the frame alignment bytes of the SONET/SDH protocol as references in order to compare these clocks. As a test bed for the experiment, we will use the Swedish University Computer Network (SUNET). A preliminary assessment of the technique in a lab environment will be performed late 2005