Software defined network and a communication network comprising the same

A non-transitory computer-readable storage medium comprising computer-executable instructions which, when executed by a processor, cause a computing device to perform a method of operating a Layer 7 Software Defined Network (SDN) in a communication network, the Layer 7 SDN comprising a routing function, the routing function comprising circuitry of a server on which the Layer 7 SDN is implemented, or comprising one or more second network switches, the method comprising:

• configuring the Layer 7 SDN to act as an entity in a first service chain of one or more entities through which a data flow is routable by one or more first network switches of a Layer 2 to Layer 4 SDN in the communication network, wherein the first service chain comprises one or more service applications each for performing a Layer 2 , a Layer 3, or a Layer 4 service on data from the data flow;
• and
• configuring the circuitry or the one or more second network switches of the Layer 7 SDN to route data from the data flow received at the Layer 7 SDN through a second service chain comprising one or more SDN service applications, wherein at least one of the one or more SDN service applications of the second service chain is for performing a Layer 7 service on data from the data flow.