Figure 17-19 Network Diagram
Both Switch 1 and Switch 2 have networks that consist of
various devices such as computers, printers, and so on.
Router 2 is the Internet router with firewall functionality
and a connection to the service provider.
SOFTWARE-DEFINED NETWORKING
The term software-defined networking (SDN) applies to
a type of network architecture design that enables IT
managers and network engineers to manage, control,
and optimize network resources programmatically.
SDN essentially decouples network configuration and
data flow engineering, regardless of the underlying
hardware infrastructure. It allows you to consistently
control the network by using standard open APIs.
Networks are often shown using a three-level
architecture, as shown in Figure 17-20, which consists of
hardware and two planes:
Data plane: As described earlier in this chapter, a router can route
packets faster by using techniques such as fast switching or CEF
switching. These techniques for punting packets from the incoming
interface to the outgoing interface operate on what is traditionally
known as the data plane. The main objective of the data plane is to
determine how the incoming packet on a port must be forwarded to an
outgoing port, based on specific values in the packet headers.
Control plane: Routing protocols and other protocols make up the
control plane. The control plane determines how a packet is routed
among routers or other network elements as the packet traverses end-
to-end from source host to destination host. The control plane also
deals with packets that are destined for the router itself. Device and
network management are also part of the control plane. Management