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new section to ospf

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OSPF versus IS-IS
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netravnen 2018-02-18 12:54:36 +01:00
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chapter/layer3.tex
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@ -49,9 +49,7 @@ Always remember the following points for Cisco devices:\cite{wiki:Administrative
Used in IP networks (v4) and a \gls{lsr} protocol. Defined as OSPFv2 on \rfc{2328} Used in IP networks (v4) and a \gls{lsr} protocol. Defined as OSPFv2 on \rfc{2328}
from 1998. v1 first published as a \gls{rfc} back in 1989. From closely watching from 1998. v1 first published as a \gls{rfc} back in 1989. From closely watching
the development of the \gls{isis} routing protocol. As they were developed in the development of the \gls{isis} routing protocol. As they were developed in
%the \gls{ietf} and the \gls{iso} organizations receptively. the \gls{ietf} and the \gls{iso} organizations receptively.\cite{Theendle83:online}
\cite{Theendle83:online}
\subsection{Algorithm} \subsection{Algorithm}
@ -65,6 +63,44 @@ using IP protocol 89 and multicast address 224.0.0.5 for link-local updates and
\subsection{Filtering} \subsection{Filtering}
\subsection[OSPF vs IS-IS]{OSPF versus IS-IS}
This is a long-standing battle between routing protocols of the 1990s. Compared
there were quite a number of differences between \gls{ospf} and
\gls{isis}.\cite{JuniperKatz2000:online}
\begin{itemize}
\item \gls{ospf} was developed at \gls{ietf}
\begin{itemize}
\item Very strictly defined
\item Optimized hard for \gls{ipv4}
\item Areas separated by routers
\item Updates done over \gls{ip}
\end{itemize}
\item \gls{isis} in \gls{iso}
\begin{itemize}
\item Loosely defined in part because of less interest in development
from the \gls{ietf}.
\item Very extensible. So protocol support can be implemented while
only extending the specification.
\item L1/L2 areas separated on links instead of routers
\item Updates sent directly on the link instead of being encapsulated
in \gls{ip} packets.
\end{itemize}
\end{itemize}
This is all good and all that. Things have changed since the starting point of
both protocols being defined in the late 1980s.
\gls{isis} had a stable implementation up through the 1990s and became the
standard of the era in \gls{isp} networks. Where as \gls{ospf} remained largely
the standard in medium-large enterprise networks.
Today in late 2010s. Many of the things that made the difference is being
considered being largely irrelevant. Both because computing hardware has come a
long way since and the optimizations implemented in the protocols is defined
for yesterdays networks of the 1990s. Not the 2010s.
\newpage \newpage
\section{IS-IS} \section{IS-IS}