Performance improvement due to secondary LSP re-routing in MPLS over optical networks

In MPLS over optical networks, the lightpath cannot be released if it accommodates one LSP. This causes inefficiency in channel utilization in the optical links that the lightpath traverses. If all the LSPs accommodated in a lightpath can be re-routed to other lightpaths, this lightpath can then be released. This paper proposes an efficient re-routing scheme to remove secondary LSPs from selected lightpaths through which the efficiency of channel utilization in the optical links is increased, and the performance of LSP establishment is improved. The conveyed traffic is not affected by re-routing only secondary LSPs. The effectiveness of the proposed re-routing scheme is verified by computer simulation. Due to secondary LSP re-routing, the loss rate of LSP requests can be improved under a normal traffic load although it increases slightly under a heavy traffic load. Performance improvement is remarkable when the idle bandwidth information of each lightpath is restrictively advertised by the routing protocol.