From 2a9fe9cf8292390dea581226dcaff7a672e73a70 Mon Sep 17 00:00:00 2001 From: Christoffer Hansen Date: Sun, 18 Feb 2018 12:54:36 +0100 Subject: [PATCH] new section to ospf OSPF versus IS-IS --- chapter/layer3.tex | 42 +++++++++++++++++++++++++++++++++++++++--- 1 file changed, 39 insertions(+), 3 deletions(-) diff --git a/chapter/layer3.tex b/chapter/layer3.tex index 75d948f..f787f92 100644 --- a/chapter/layer3.tex +++ b/chapter/layer3.tex @@ -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} 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 \gls{ietf} and the \gls{iso} organizations receptively. - -\cite{Theendle83:online} +the \gls{ietf} and the \gls{iso} organizations receptively.\cite{Theendle83:online} \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[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 \section{IS-IS}