What are flow rules in SDN?

In SDN, the controller communicates with switches through a well-defined application programming interface (API). Currently, the popular API is OpenFlow protocol [13], [14]. The OpenFlow switch contains a flow table that consists of flow rules. The flow rule comprises of match fields, counters and set of instructions.

What is true about SDN controller?

An SDN controller is the application that acts as a strategic control point in a software-defined network. An SDN controller manages flow control to the switches/routers “below” (via southbound APIs) and the applications and business logic “above” (via northbound APIs) to deploy intelligent networks.

What is the first process that will occur once a packet arrives at the OpenFlow switch?

Upon a packet arrival at an OpenFlow switch, packet header fields are extracted and matched against the matching fields portion of the flow table entries. If a matching entry is found, the switch applies the appropriate set of instructions, or actions, associated with the matched flow entry.

Which protocol is followed for rule placement in SDN?

The OpenFlow protocol
The OpenFlow protocol implements the SDN concept by abstracting network communications as flows to be processed by network elements. In OpenFlow, the high-level policies are translated into network primitives called rules that are distributed over the network.

Where are SDN flow tables stored?

SDN divides the network organization into the control plane and data plane. The control plane has a set of rules for processing the packet, and when those packets enter the data plane, they are processed according to the pertinent rule. The rules are stored and managed in the flow table inside the switch.

Which protocol is used between control plane and application plane in SDN?

SDN architecture separates the control and data planes of the network stack. The OpenFlow protocol is an open source way to have the different planes of a network communicate. SDN controllers communicate with applications via the northbound API and with the network infrastructure via southbound APIs.

What does a switch send packet in message to a controller in SDN?

Switch-2 sends the LLDP frame back to the SDN controller through a ‘packet-in’ message. Upon receiving the ‘packet-in’ message, the controller creates a link between the port number (port) and datapath ID (dpid) combination on switch-1 and port/dpid on switch-2.