Carrier-grade networks comprise several layers where different protocols coexist.
Nowadays, most of these networks have different control planes to manage routing on
different layers, leading to a suboptimal use of the network resources and additional
operational costs. However, some routers are able to encapsulate, decapsulate and
convert protocols and act as a liaison between these layers. A unified control plane
would be useful to optimize the use of the network resources and automate the routing
configurations. Software-Defined Networking (SDN) based architectures, such as OpenFlow,
offer a chance to design such a control plane. One of the most important problems
to deal with in this design is the path computation process. Classical path computation
algorithms cannot resolve the problem as they do not take into account encapsulations
and conversions of protocols. In this paper, we propose algorithms to solve this problem
and study several cases: Path computation without bandwidth constraint, under bandwidth
constraint and under other Quality of Service constraints. We study the complexity
and the scalability of our algorithms and evaluate their performances on real topologies.
The results show that they outperform the previous ones proposed in the literature.