Bridge priority provisioning for maximizing equal cost shortest path availability

Shortest Path Bridging (SPB) is a new layer 2 switching technology which is the latest on the IEEE 802.3 Ethernet evolution path and provides improved scalability. It is suitable for large-scale cloud data center networks that require hundreds or thousands of switches (or bridges) to connect up to tens of thousands of servers. In SPB, 16 ECT (equal cost tree) algorithms are introduced to select one of multiple equal cost shortest paths (ECSPs). However, some ECSPs may not be selected by these ECT algorithms at all. In this paper, we propose provisioning bridge priority to address this issue. The proposed distinct XOR relation (DXR) constraint on the bridge priority is shown to allow maximum number of ECSPs to be selected by the ECT algorithms.