Performance Evaluation and Design of Polymorphous OBS Networks With Guaranteed TDM Services

In polymorphous optical burst-switched (POBS) networks, the burst control packets (BCPs) of conventional just-enough-time based signalling OBS networks are given extended properties which enable them not only to reserve fixed time-slots for asynchronous data bursts, but also to allocate TDM reservations for periodic streams of data, and even a complete wavelength for high-bandwidth demanding services. This allows POBS to provide a flexible, yet transparent, approach for supporting the idiosyncrasies of today's most popular services over the same underlying network architecture. In POBS, the spare gaps in between synchronous TDM reservations can be used for the allocation of best-effort data bursts, leading to a more efficient utilisation of the optical capacity. This work shows how to extend the well-known Erlang fixed point procedure to evaluate the performance behavior of POBS networks, whereby asynchronous data bursts coexist with high-priority periodic TDM reservations. The performance evaluation algorithm is applied to a number of case scenarios, showing the benefits arisen due to the flexibility of POBS networks.