A Broadcast Based Link Discovery Scheme for Minimizing Messages in Software Defined Networks

Software defined network (SDN) with disjoint control and data plane enables the controller to address network requirement better. A significant issue in such networks is how the network resources are allocated by the controller based on the demand, for instance, allocation of path with less delay, less error rate and so forth. The controller allocate such network resources by enabling link discovery between switches. SDN utilizes protocol like link layer discovery protocol (LLDP) for links to be identified in OpenFlow devices. The detection of links in OpenFlow devices requires a huge number of PACKET OUT (P
out
) messages from the controller to be sent across every active interfaces of the switch which might limit the controller performance. This paper introduces a Broadcast based Link Discovery (BBLD) scheme which lowers messages required to obtain the link discovery in OpenFlow switches (OFS’s) by dispatching a solitary P
out
from the SDN controller (unlike a unicast message from the controller in case of LLDP) to any OpenFlow switch (OFS), which then circulates the same to the nodes successively. Experiments performed with Mininet reveal that messages required to obtain similar link discovery are reduced by an average of (28%-42.4%) under varied set of topologies.