Multipath routing in Path Computation Element (PCE): Protocol extensions and implementation

The Path Computation Element (PCE) and PCE communication Protocol (PCEP) have been standardized by the IETF. The scalability of PCE and its capability of constrained path computation make it especially attractive to carriers. Considering the latest extensions on related protocols, PCE has become the de-facto standard in connection service provisioning, especially in the carrier grade networks with strict QoS requirements. Whereas the PCE frameworks proposed to date have exclusively considered single path computation, the increasing demand for flexible services with high bandwidth requirement is driving PCE towards multipath techniques. This paper proposes the first implementation and protocol extensions of PCE with capability of multipath computation in line with PCE standards. We show that the overhead, i.e., signaling delay, caused by the multipath extensions in the PCEs is acceptable, while the blocking ratio of connection requests can be significantly reduced. We also suggest that the number of paths can be limited in the multipath routing algorithms to reduce the overhead caused by multipath extensions at a price of slight increase of blocking ratio. The results show that the presented multipath PCE system is scalable in large networks, with average signaling delay in the order of milliseconds. Therefore, it is feasible in practice and it can be beneficial for transport networks with emerging new applications, such as optical and Carrier Ethernet networks.