  SDN promises to overcome vendor lock-in by enabling a multi-vendor hardware
and software ecosystem in operator networks. However, we observe that this is
currently not happening. A framework allowing to compose SDN applications
combining different frameworks can help revert the trend. In this paper, we
analyze the challenges in the current SDN landscape and then present the
multi-controller SDN framework developed by the NetIDE project. Our
architecture supports different SDN southbound protocols and we have
implemented a proof of concept using the OpenFlow protocol, which has given us
a greater insight on its shortcomings.
