  Link capacity dimensioning is the periodic task where ISPs have to make
provisions for sudden traffic bursts and network failures to assure
uninterrupted operations. This provision comes in the form of link working
capacities with noticeable amounts of headroom, i.e., spare capacities that are
used in case of congestions or network failures. Distributed routing protocols
like OSPF provide convergence after network failures and have proven their
reliable operation over decades, but require overprovisioning and headroom of
over 50%. However, SDN has recently been proposed to either replace or work
together with OSPF in routing Internet traffic. This paper addresses the
question of how to robustly dimension the link capacities in emerging hybrid
SDN/OSPF networks. We analyze the networks with various implementations of
hybrid SDN/OSPF control planes, and show that our idea of SDN Partitioning
requires less amounts of spare capacity compared to legacy or other hybrid
SDN/OSPF schemes, outperformed only by a full SDN deployment.
