In elastic networking,the WDM fixed frequency grid is replaced by a more flexible structure,in which the spectrum is organized in frequency slots,and each traffic flow is assigned to an appropriate set of contiguous s...In elastic networking,the WDM fixed frequency grid is replaced by a more flexible structure,in which the spectrum is organized in frequency slots,and each traffic flow is assigned to an appropriate set of contiguous slots.The classical RWA(routing and wavelength assignment)problem is then replaced by the RSA(routing and spectrum assignment)problem.In this paper,we discuss the SA(spectrum assignment)problem in a single link,where it is not coupled to the routing problem,thus allowing for a better understanding of its dynamics.The best SA algorithm,taken as anyone who minimizes the average time it takes to provide total exhaustion of the initial available spectrum under incremental traffic,is shown to be a function of the traffic profile.It is shown that the greedy algorithm,which is unaware of the traffic profile,may impose severe performance penalties if the request rates increase with the number of requested slots.However,no penalty is incurred by more friendly profiles,like the uniform one.展开更多
文摘In elastic networking,the WDM fixed frequency grid is replaced by a more flexible structure,in which the spectrum is organized in frequency slots,and each traffic flow is assigned to an appropriate set of contiguous slots.The classical RWA(routing and wavelength assignment)problem is then replaced by the RSA(routing and spectrum assignment)problem.In this paper,we discuss the SA(spectrum assignment)problem in a single link,where it is not coupled to the routing problem,thus allowing for a better understanding of its dynamics.The best SA algorithm,taken as anyone who minimizes the average time it takes to provide total exhaustion of the initial available spectrum under incremental traffic,is shown to be a function of the traffic profile.It is shown that the greedy algorithm,which is unaware of the traffic profile,may impose severe performance penalties if the request rates increase with the number of requested slots.However,no penalty is incurred by more friendly profiles,like the uniform one.
