Efficient sequencing techniques for variable-length messages in WDM networks

Message sequencing and channel assignment are two important issues that nee d to be addressed when scheduling variable-length messages in a wavelength division multiplexing (WDM) network. Channel assignment addresses the probl em of choosing an appropriate data channel via which a message is transmitt ed to a node. This problem has been addressed extensively in the literature . On the other hand, message sequencing which addresses the order in which messages are sent, has rarely been addressed. In this paper, we propose a s et of scheduling techniques for single-hop WDM passive star networks, which address both the sequencing aspect and the assignment aspect of the proble m, In particular, we develop two priority schemes for sequencing messages i n a WDM network in order to increase the overall performance of the network . We evaluate the proposed algorithms, using analytical modeling and extens ive discrete-event simulations, by comparing their performance with state-o f-the-art scheduling algorithms that only address the assignment problem [9 ], We find that significant improvement in performance can be achieved usin g our scheduling algorithms where message sequencing and channel assignment are simultaneously taken into consideration. This suggests that, when sche duling messages in WDM networks, one has to consider message sequencing, as well as channel assignment. As a result, we anticipate that this research mill open new directions into the problem of on-line scheduling in WDM netw orks.