SDN and ForCES based optimal network topology discovery

Software-defined Networking proposes an alternative paradigm on network programmability based on the separation of control and forwarding planes. Discovering network elements in a dynamic and optimized fashion, able to cope with the ever-growing network traffic, is a key requirement for SDN networks, in order to ensure a data center’s robustness and manageability. OpenFlow’s approach for creating the topology map is by exchanging LLDP frames between the controller and the forwarding elements.

This paper proposes a better usage of LLDP by taking advantage of existing hardware capabilities to extract information directly from the data plane to the control plane in order to construct a dynamic and automatic topology discovery algorithm. Following this procedure to obtain the topology map and using the IETF’s ForCES framework, we managed to model a generic method for extracting the required LLDP information from the datapath to the controller.