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.