2
SDN (Software-Defined Networking)
The SDN (Software-Defined Networking) technology is at the
heart of this book. It was introduced with virtualization, enabling
networking devices to be transformed into software. Associated with
this definition, a new architecture has been defined: it decouples the
data level from the control level. Up until now, forwarding tables have
been computed in a distributed manner by each router or switch. In the
new architecture, the computations for optimal control are performed
by a different device, called the controller. Generally, the controller is
centralized, but it can perfectly well be distributed. Before taking a
closer look at this new architecture, let us examine the reasons for this
new paradigm.
The limitations of traditional architectures are becoming
significant: at present, modern networks no longer optimize the costs
at all (i.e. the CAPEX and OPEX). In addition, the networks are not
agile. The time to market is much too long, and the provisioning
techniques are not fast enough. In addition, the networks are
completely unconnected to the services, and the following points need
to be taken into account in the new SDN paradigm:
– overall needs analysis;
– dynamic, rather than static, configuration;
– dynamic, rather than static, policies used;
– much greater information feedback than is the case at present;
Software Networks: Virtualization, SDN, 5G and Security, First Edition. Guy Pujolle.
© ISTE Ltd 2015. Published by ISTE Ltd and John Wiley & Sons, Inc.
www.it-ebooks.info