diff --git a/chapter/section/spanningtree.tex b/chapter/section/spanningtree.tex index 63409af..9134fb1 100644 --- a/chapter/section/spanningtree.tex +++ b/chapter/section/spanningtree.tex @@ -312,13 +312,13 @@ Cisco did on their part early on enhance the original spanning tree standard wit \centering \caption{UDLD|Loopguard compared} \label{udldloopguard} - \resizebox{\textwidth}{!}{% + \resizebox{\columnwidth}{!}{% \begin{tabular}{|l|l|l|} \hline - \textbf{Functionality} & \textbf{Loop guard} & \textbf{UDLD} \\ \hline + \thead{Functionality} & \thead{Loop guard} & \thead{UDLD} \\ \hline Action granularity & Per vlan & Per port \\ \hline - Protection against stp failures caused by uni-directional links & Yes, when enabled on all potential non-designated ports in redundant topology & Yes, when enabled on all links in redundant topology \\ \hline - Protection against stp failures caused by problem in software resulting in designated switch not sending bpdus & Yes & No \\ \hline + \makecell{Protection against STP\\failures caused by uni-directional\\ links} & \makecell{Yes, when enabled on all\\potential non-designated ports\\in redundant topology} & \makecell{Yes, when enabled on all\\links in redundant topology} \\ \hline + \makecell{Protection against STP\\failures caused by problem in\\software resulting in designated\\switch not sending BPDUs} & Yes & No \\ \hline Protection against mis-wiring & No & Yes \\ \hline \end{tabular}% } @@ -326,12 +326,51 @@ Cisco did on their part early on enhance the original spanning tree standard wit \fig{spanningtree/stpbestpractice}{stpbestpractice}{STP best practice} -\subsection{Multiple Spanning Tree} +\section{Multiple Spanning Tree} \begin{itemize} \item \itemtitle{Known limitations}{Regarding the cisco world of things} \begin{enumerate} \item A maximum of 16 instances is supported. {\footnotesize From 0 to 15.} \end{enumerate} + \item \textbf{Beware} that instance 0 is the \textit{I}nternal \textit{S}panning \textit{T}ree. And therefore cannot be configured for user-mapped Vlans. + \item Aggregates the configured vlans into groups/instances/processes. This in turn provides lower resource utilization on switches. \dWinkey + \item Backwards compatible with 802.1D STP/802.1w/RSTP and Cisco PVST+. + \item Converges faster than PVRST+. + \item \itemtitle{Challenges}{Arises because of older hardware and the architecture of the protocol} + \begin{enumerate} + \item Operability with older/legacy hardware/equipment is not always possible. + \item \textit{Of course} it is more complex compared to standard STP (older) protocols. {\footnotesize Staff may require teachings of the way of the protocol.} + \end{enumerate} \end{itemize} - \ No newline at end of file + +\begin{table}[h] + \centering + \caption{MST Attributes} + \label{mstattr} + \resizebox{\columnwidth}{!}{% + \begin{tabular}{|l|l|} + \hline + \thead{Data} & \thead{What ?} \\ \hline + 32 bytes & alphanumeric configuration name \\ \hline + 2 bytes & configuration revision number \\ \hline + Table of 4096 elements & \makecell{associates each of the potential\\4096 VLANs with an instance} \\ \hline + \end{tabular}% + } +\end{table} + +\subsection{MST Regions} + +It is the network admins job to propagate an even configuration to all switches in a single region by using CLI or SNMP. Currently IOS does not support any other options to do the job. + +\begin{itemize} + \item \itemtitle{Boundaries}{MST differs between regions by} + \begin{enumerate} + \item sending a digest computer from the Vlan-to-instance mapping table of the switch sending the digest. + \item the characteristics of the MST protocol for that single switch. + \end{enumerate} + \item if computed digest and MST characteristics between switches is \textit{found matching}, the switches considers themselves part of the same MST region. + \item \textbf{Beware} that unlike VTP, MST does not automatically increase the configuration revision number. This \textit{has to be done} manually. +\end{itemize} + +\fig{spanningtree/mstregions}{mstregions}{MST Regions} \ No newline at end of file diff --git a/img/spanningtree/mstregions.png b/img/spanningtree/mstregions.png new file mode 100644 index 0000000..df84756 Binary files /dev/null and b/img/spanningtree/mstregions.png differ