Electronics_For_You_July_2017

http://www.EFymag.com ElEctronics For you | July 2017 43

networking

and access-control algorithms are centrally managed by
the control plane.

OpenFlow protocol

OpenFlow is an application program interface (API) that
provides interface between data and the control plane.
It controls the forwarding table of the router from a re-
mote location. OpenFlow based controllers maintain an
inventory of all paths of the network and store these for
further allocation. The controllers update the flow table
as per network traffic, using OpenFlow protocol.
Northbound.
In general terms,
northbound in-
terface allows net-
work components
to communicate
with higher-level
components of
the same net-
work. Here,
northbound is the
API that interfac-
es control plane

Fig. 5: SDN architecture components

Fig. 6: Traditional control mechanism (Image
courtesy: http://www.ieiit.cnr.it))

Distributed algorithm running

between neighbours

Complicated task-specific distributed algorithm

API API API

Business Applications

Infrastructure Layer

Control Layer

Application Layer

Network Device

Network Device

Network Device

Network Device

Network Device

Control Data Plane Interface

(e.g., OpenFlow)

Network Services

SDN

Control

Software

Fig. 7: Controlling mechanism in SDN (Courtesy: http://www.ieiit.cnr.it))

Forwarding Model

Network OS (e.g., NOX)

Global Network View

Control Program

Routing, access control, etc