SDN (Software-Defined Networking) 19
2.2. The ONF architecture
In order for this new world of SDN to have a chance of being
successful, it has to be standardized. This standardization was carried
out by the ONF (Open Network Foundation), which was set up under
the auspices of large companies in California, following the proposal
of this architecture by Stanford University and Nicira.
The architecture proposed by the ONF is shown in Figure 2.5. It
comprises three layers. The bottom layer is an abstraction layer, which
decouples the hardware from the software, and is responsible for data
transport. This level describes the protocols and algorithms which
enable IP packets to advance through the network to their destination.
This is called the infrastructure plane. The second layer is the control
plane. This plane contains the controllers providing control data to
the data plane so that the data are channeled as effectively as
possible. The ONF’s vision is to centralize control in order to facilitate
the recovery of a great deal of information on all the clients. The
centralized controller enables obtaining a sort of intelligence. The
infrastructure to be managed is distributed between the controllers. Of
course, we need to take account of the problems of a centralized
environment, and therefore duplicate the decision elements.
Controllers carry out different functions, such as the provision of
infrastructure, the distribution (or otherwise) of loads on different
network devices to optimize performances or reduce energy
consumption. The controller is also in charge of the deployment of
firewalls and servers necessary for the proper operation of the network
and a management system. These different machines must be put in
the most appropriate places.
Finally, the uppermost layer, the application plane, is responsible
for the applications needed by the clients and for their requirements in
terms of networking, storage, computation, security and management.
This layer introduces the programmability of the applications, and
sends the controller all of the necessary elements to open the software
networks tailored to the needs of the applications. This layer also
www.it-ebooks.info
2.2. The ONF architecture
In order for this new world of SDN to have a chance of being
successful, it has to be standardized. This standardization was carried
out by the ONF (Open Network Foundation), which was set up under
the auspices of large companies in California, following the proposal
of this architecture by Stanford University and Nicira.
The architecture proposed by the ONF is shown in Figure 2.5. It
comprises three layers. The bottom layer is an abstraction layer, which
decouples the hardware from the software, and is responsible for data
transport. This level describes the protocols and algorithms which
enable IP packets to advance through the network to their destination.
This is called the infrastructure plane. The second layer is the control
plane. This plane contains the controllers providing control data to
the data plane so that the data are channeled as effectively as
possible. The ONF’s vision is to centralize control in order to facilitate
the recovery of a great deal of information on all the clients. The
centralized controller enables obtaining a sort of intelligence. The
infrastructure to be managed is distributed between the controllers. Of
course, we need to take account of the problems of a centralized
environment, and therefore duplicate the decision elements.
Controllers carry out different functions, such as the provision of
infrastructure, the distribution (or otherwise) of loads on different
network devices to optimize performances or reduce energy
consumption. The controller is also in charge of the deployment of
firewalls and servers necessary for the proper operation of the network
and a management system. These different machines must be put in
the most appropriate places.
Finally, the uppermost layer, the application plane, is responsible
for the applications needed by the clients and for their requirements in
terms of networking, storage, computation, security and management.
This layer introduces the programmability of the applications, and
sends the controller all of the necessary elements to open the software
networks tailored to the needs of the applications. This layer also
www.it-ebooks.info