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chapter/section/spanningtree.tex: Updated section Multiple Spanning Tree
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@ -312,13 +312,13 @@ Cisco did on their part early on enhance the original spanning tree standard wit
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\centering
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\centering
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\caption{UDLD|Loopguard compared}
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\caption{UDLD|Loopguard compared}
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\label{udldloopguard}
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\label{udldloopguard}
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\resizebox{\textwidth}{!}{%
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\resizebox{\columnwidth}{!}{%
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\begin{tabular}{|l|l|l|}
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\begin{tabular}{|l|l|l|}
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\hline
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\hline
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\textbf{Functionality} & \textbf{Loop guard} & \textbf{UDLD} \\ \hline
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\thead{Functionality} & \thead{Loop guard} & \thead{UDLD} \\ \hline
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Action granularity & Per vlan & Per port \\ \hline
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Action granularity & Per vlan & Per port \\ \hline
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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
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\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
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Protection against stp failures caused by problem in software resulting in designated switch not sending bpdus & Yes & No \\ \hline
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\makecell{Protection against STP\\failures caused by problem in\\software resulting in designated\\switch not sending BPDUs} & Yes & No \\ \hline
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Protection against mis-wiring & No & Yes \\ \hline
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Protection against mis-wiring & No & Yes \\ \hline
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\end{tabular}%
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\end{tabular}%
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}
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}
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@ -326,12 +326,51 @@ Cisco did on their part early on enhance the original spanning tree standard wit
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\fig{spanningtree/stpbestpractice}{stpbestpractice}{STP best practice}
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\fig{spanningtree/stpbestpractice}{stpbestpractice}{STP best practice}
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\subsection{Multiple Spanning Tree}
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\section{Multiple Spanning Tree}
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\begin{itemize}
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\begin{itemize}
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\item \itemtitle{Known limitations}{Regarding the cisco world of things}
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\item \itemtitle{Known limitations}{Regarding the cisco world of things}
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\begin{enumerate}
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\begin{enumerate}
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\item A maximum of 16 instances is supported. {\footnotesize From 0 to 15.}
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\item A maximum of 16 instances is supported. {\footnotesize From 0 to 15.}
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\end{enumerate}
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\end{enumerate}
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\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.
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\item Aggregates the configured vlans into groups/instances/processes. This in turn provides lower resource utilization on switches. \dWinkey
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\item Backwards compatible with 802.1D STP/802.1w/RSTP and Cisco PVST+.
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\item Converges faster than PVRST+.
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\item \itemtitle{Challenges}{Arises because of older hardware and the architecture of the protocol}
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\begin{enumerate}
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\item Operability with older/legacy hardware/equipment is not always possible.
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\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.}
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\end{enumerate}
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\end{itemize}
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\end{itemize}
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\begin{table}[h]
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\centering
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\caption{MST Attributes}
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\label{mstattr}
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\resizebox{\columnwidth}{!}{%
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\begin{tabular}{|l|l|}
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\hline
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\thead{Data} & \thead{What ?} \\ \hline
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32 bytes & alphanumeric configuration name \\ \hline
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2 bytes & configuration revision number \\ \hline
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Table of 4096 elements & \makecell{associates each of the potential\\4096 VLANs with an instance} \\ \hline
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\end{tabular}%
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}
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\end{table}
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\subsection{MST Regions}
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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.
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\begin{itemize}
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\item \itemtitle{Boundaries}{MST differs between regions by}
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\begin{enumerate}
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\item sending a digest computer from the Vlan-to-instance mapping table of the switch sending the digest.
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\item the characteristics of the MST protocol for that single switch.
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\end{enumerate}
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\item if computed digest and MST characteristics between switches is \textit{found matching}, the switches considers themselves part of the same MST region.
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\item \textbf{Beware} that unlike VTP, MST does not automatically increase the configuration revision number. This \textit{has to be done} manually.
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\end{itemize}
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\fig{spanningtree/mstregions}{mstregions}{MST Regions}
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img/spanningtree/mstregions.png
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