Similar Yet Different: Protocol Design Choices in IS-IS and OSPF

This paper summarizes our comparative study on the design choices of two classic link-state routing protocols: IS-IS and OSPF. Although both protocols are based on the same algorithmic foundations for computing best paths across large networks, they made different choices at various aspects in the protocol designs. We selected ten major design differences between the two to understand the reasoning behind their choices. We hope that this comparative study helps shed new light on the design space of link-state routing protocols and prove useful to future routing protocol design efforts.