Extending OSPF for large scale MPLS networks

Abstract

With the current growth rate that networks are witnessing, it is essential to have routing protocols that can adjust to scale with this growth. OSPF (open shortest path first), the most widely used interior gateway protocol, needs to be adaptive enough to accommodate rapid changes to the complex nature of the Internet and other ISP networks. We present extensions to OSPF and OSPF-TE (OSPF with traffic engineering) that can be used to optimize such protocols for large scale MPLS networks. OSPF-TE specifies methods of adding traffic engineering capabilities to OSPF. The extensions to OSPF are designed to be as generic as possible while trying to address several issues related to the empowerment of IP networks with MPLS. This work shows how link state advertisements in OSPF, with a slight modification, can be utilized to load balance both control traffic and label switched paths in networks with parallel links and equal cost multipaths. In addition, we show how further optimization can be achieved for parallel links to reduce the size of the OSPF link state database and thus reduce CPU consumption