The protocol of the internet used since 1994.\cite{wiki:Border_Gateway_Protocol}
\begin{itemize}
\item\itemhead{Properties}
\begin{itemize}
\item Uses tcp/179 as \gls{dst} port
\item Sends keep-alive message every 1 minute
\item Keep-alive message is 19 byte
\end{itemize}
\item\itemhead{Route exchange}
\begin{itemize}
\item Routes can be aggregated between \Glspl{as} by use of route-maps mechanism.
\item
\end{itemize}
\item\itemhead{States}
\begin{enumerate}
\item Idle: \Gls{bgp} while initializing refuses all incoming connections. Will initiate \Gls{tcp} connection to peer.
\item Connect: Waits for \Gls{tcp} connection. If \Gls{tcp} is established goes to state OpenSent. If \Gls{tcp} is \textit{un}successful ConnectRetry timer is started and then goes to Active state.