\chapter{Conceptual Design of a SDN Controller as Network Supervisor}
\label{ch:conceptual-design}

\section{Conceptual Structures}
\label{ch:conceptual-design:structures}

This section discusses the basic conceptual organization forms for data networks, as this seems to not clear in many contexts. 

\subsection{Principal Network Domain (PND)}

Any network consists out of basic components that are the collection of devices (called hosts later on) used to form such particular network. These components, let it be any device attached to this network and the (physical) links, with their control-, data-, and management planes form the Principal Network Domain (PND). A specific network controller is in control of the specific components of a network. 

The differentiation between the PND and the following definitions of network domain, IP network, etc is important for the design of a network controller that is supervising a network in its whole. The PND is the concept used by the network controller to keep track of all hosts and links associated~\footnote{XXXwhat means \emph{associated} exactly?} to this controller. 

\section{Building Blocks}
\label{ch:conceptual-design:collection}

Some conceptual building blocks for a network supervisor:
\begin{description}
	\item [host inventory] \hfill \\ This contains all known hosts, independent their relationship, of the network. This includes their hardware configuration, such as, interfaces attached to a particular host.
	\item [host configuration] \hfill \\  This is based on the information provided by the host inventory and contains the actual operational configuration of the hosts. This will probably contain only the configuration of the network devices, such as, switches and routers, potentially also servers, but not end-hosts.		
	\item [Network ] \hfill \\ 
	\item [Network Configuration)] \hfill \\ 
	\item [Southbound Interface (SBI)] \hfill \\ 
	\item [Northbound Interface (SBI)] \hfill \\ 
	\item [East-West-bound Interface (SBI)] \hfill \\ 
\end{description}
