SDN is an architecture that is based on the abstraction of the network controls, and which foresees the concept of programmable network... without further ado let's first review as to what is SDN and why we should re-look at our current and future network architecture.
In any commercial network product the internal architecture is divided into two conceptual parts.
- Control plane
- Data plane
Control Plane - The control plane in a network device provides management functions, that allows anyone authorised to perform configuration or any other management task on the device. The control pane functions are implemented in software or on separate embedded processors.
Data Plane - The data plane provides the functionality needed to process packets, and includes network interface hardware, packet ingress/egress facilities and packet forwarding mechanism. Data plane modules are implemented in hardware and are highly optimized.
Control Plane Modules and the H/W Interface
The control plane includes multiple software modules, via each of which the network device could be accessed and configured, CLI,http, snmp are the most common network management interfaces.
Note that the network vendors will provide features on a interface which are not available on other interfaces, this is done to differentiate the vendor products from others and this also results in indirect dependency on the vendor for particular feature set, as configuring other network devices on your network from the same vendor will require those vendor specific features.
Now to support multiple software modules the network vendor creates a "common interface" to perform operations.
The above is what is currently present in your network devices..now what changes
with SDN...
SDN
In SDN most of the control plane functions are moved to a external controller, an additional control module is added, via this control module the external controller is able to modify and monitor the network.
The management s/w running on the external controller can now directly configure the forwarding table in the data plane. i.e. external controller via the SDN module can now communicate with the "common interface". Now the custom features set available via the vendor's custom interface is no longer in the equation.. i.e. you are no longer dependent on the vendor, now you are in control...
Now, imagine if you could implement a end-to-end SDN in your network, where the network devices are just a commodity..think...
In the next article I will go thru the nuts n bolts of SDN with a how-to implement...
In the next article I will go thru the nuts n bolts of SDN with a how-to implement...
