Due to difficulties in distributing a single global clock signal over increasingly large chip areas, a globally asynchronous, locally synchronous design is considered a promising technique in the system on a chip (SoC) era. In the context of today's increasingly complex SoCs, there is a need for design methodologies that start at higher levels of abstraction. Much of the previous work has been devoted to design of asynchronous communication schemes such as mixed clock FIFOs and pausible clocks for globally asynchronous, locally synchronous systems, but at low levels of abstraction, such as circuit level. To enable early design evaluation of such schemes, this paper proposes to use a SystemC-based modeling methodology for the asynchronous communication among various locally synchronous islands. The modeling framework encompasses various levels of abstraction and enables system-level validation of circuit or RT level hardware descriptions, as well as their impact on high-level design decisions.