lsas.tex

\section{Link-State Advertisements}
\label{sec:lsas}

Link-State Advertisements (LSAs) represent pieces of routing information distributed by routers.

\subsection{LSA Base Class}
\label{sec:lsa-base-class}

All three LSA implementations inherit from an LSA Base class, \texttt{Lsa}, which maintains information that is included in each LSA.
The \texttt{LSA} class contains the following member variables:
\begin{itemize}
\item \textbf{Origin Router} - the router that advertised the LSA. Specifically, this is a name prefix that follows the NLSR convention of router naming.
\item \textbf{Sequence Number} - a number used to indicate the LSA's version. Because sequence numbers are preserved between NLSR restarts, a higher sequence number also always indicates a \emph{newer} LSA.
\item \textbf{Expiration Time Point} - a time point indicating when the LSA is no longer valid. This currently is represented as a Unix timestamp (i.e. seconds since Jan 1, 1970).
\end{itemize}

\subsection{Adjacency LSAs}
\label{sec:adjacency-lsas}

Adjacency LSAs maintain an \texttt{AdjacencyList} which contains information about all the currently \texttt{ACTIVE} neighbors of the origin router. It also includes the number of active routers, not just the list itself. This aids in serialization.

\subsection{Coordinate LSAs}
\label{sec:coordinate-lsas}

Coordinate LSAs maintain the hyperbolic angle(s) and hyperbolic radius of the origin router.

\subsection{Name LSAs}
\label{sec:name-lsas}

Name LSAs maintain a \texttt{NamePrefixList} which contains the name prefixes that are reachable at the origin router.