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chapter/section/spanningtree.tex: Updated FlexLinks + replaced tabs with 4 spaces

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chhan11 2017-05-29 08:27:11 +02:00
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chapter/section/spanningtree.tex
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@ -11,20 +11,20 @@ Spanning Tree exists for the \textbf{sole} reason to save "your" network and all
STP comes from the above desire where redundancy was wanted but no protocol existed before STP to help in this regard. STP comes from the above desire where redundancy was wanted but no protocol existed before STP to help in this regard.
\begin{table}[h] \begin{table}[h]
\centering \centering
\caption{Spanning Tree standrds} \caption{Spanning Tree standrds}
\label{stpstandards} \label{stpstandards}
\resizebox{\columnwidth}{!}{% \resizebox{\columnwidth}{!}{%
\begin{tabular}{|l|l|l|l|l|} \begin{tabular}{|l|l|l|l|l|}
\hline \hline
\textbf{} & \textbf{Standard} & \textbf{Ressource Usage} & \multicolumn{2}{l|}{\textbf{Convergence}} \\ \hline \textbf{} & \textbf{Standard} & \textbf{Ressource Usage} & \multicolumn{2}{l|}{\textbf{Convergence}} \\ \hline
CST & 802.1D & Low & Slow & All vlans \\ \hline CST & 802.1D & Low & Slow & All vlans \\ \hline
PVST+ & Cisco & High & Slow & Per vlan \\ \hline PVST+ & Cisco & High & Slow & Per vlan \\ \hline
RSTP & 802.1w & So-so (Med.) & Fast & All vlans \\ \hline RSTP & 802.1w & So-so (Med.) & Fast & All vlans \\ \hline
RPVST+ & Cisco & On-the-double (V.High) & Fast & Per vlan \\ \hline RPVST+ & Cisco & On-the-double (V.High) & Fast & Per vlan \\ \hline
MST & 802.1s & Med. - High & Fast & Vlan list \\ \hline MST & 802.1s & Med. - High & Fast & Vlan list \\ \hline
\end{tabular}% \end{tabular}%
} }
\end{table} \end{table}
\subsection{Port Roles} \subsection{Port Roles}
@ -32,25 +32,25 @@ STP comes from the above desire where redundancy was wanted but no protocol exis
When a switch is enabled for Spanning Tree. One of the following roles will have been assumed by any port on the switch in question. When a switch is enabled for Spanning Tree. One of the following roles will have been assumed by any port on the switch in question.
\begin{itemize} \begin{itemize}
\item \textbf{Root port:} Only 1 port on any switch (non-counting the root bridge!). Is always the port with the lowest metric (aka. best path) to the root bridge. \item \textbf{Root port:} Only 1 port on any switch (non-counting the root bridge!). Is always the port with the lowest metric (aka. best path) to the root bridge.
\begin{itemize} \begin{itemize}
\item The upstream/-link port closest to the root bridge on all switches apart from the root bridge. \item The upstream/-link port closest to the root bridge on all switches apart from the root bridge.
\end{itemize} \end{itemize}
\item \textbf{Designated port:} A designated port is the port on any segment closest to the root bridge and forwarding traffic. \item \textbf{Designated port:} A designated port is the port on any segment closest to the root bridge and forwarding traffic.
\begin{itemize} \begin{itemize}
\item The port on any switch in downstream direction closet to the root bridge. \item The port on any switch in downstream direction closet to the root bridge.
\end{itemize} \end{itemize}
\item \textbf{\textit{Non}-designated port:} Put in blocking mode and not currently forwarding traffic. \item \textbf{\textit{Non}-designated port:} Put in blocking mode and not currently forwarding traffic.
\begin{itemize} \begin{itemize}
\item All switch ports which did not get elected as the root or designated port. \item All switch ports which did not get elected as the root or designated port.
\end{itemize} \end{itemize}
\item \textbf{Disabled port:} The port has been one-way-or-another shut down. \item \textbf{Disabled port:} The port has been one-way-or-another shut down.
\end{itemize} \end{itemize}
\subsubsection{specific port roles} \subsubsection{specific port roles}
\begin{itemize} \begin{itemize}
\item \textbf{Alternative port} is an active port in network with an alternative path to the root bridge. A port in alternative mode will remain active but \textit{discards} all traffic until the the current designated path fails. \item \textbf{Alternative port} is an active port in network with an alternative path to the root bridge. A port in alternative mode will remain active but \textit{discards} all traffic until the the current designated path fails.
\item \textbf{Backup port} is running in active mode and \textit{discards} all traffic it recieves until the current designated port on the segment the backup port is connected to, fails. \item \textbf{Backup port} is running in active mode and \textit{discards} all traffic it recieves until the current designated port on the segment the backup port is connected to, fails.
\end{itemize} \end{itemize}
Election of ports goes in order of the following values (low is best): 1) root bridge id, 2) lowest path cost to root bridge, 3) sender bridge id, 4) sender port bridge id Election of ports goes in order of the following values (low is best): 1) root bridge id, 2) lowest path cost to root bridge, 3) sender bridge id, 4) sender port bridge id
@ -123,18 +123,18 @@ Using a \textbf{R}oot \textbf{B}rigde as the reference point for the STP instanc
\subsubsection{Port Cost} \subsubsection{Port Cost}
\begin{table}[h] \begin{table}[h]
\centering \centering
\caption{Default port cost in spanning tree} \caption{Default port cost in spanning tree}
\label{stpportcost}{!}{% \label{stpportcost}{!}{%
\begin{tabular}{|l|l|} \begin{tabular}{|l|l|}
\hline \hline
\textbf{Link} & \textbf{Default Cost} \\ \hline \textbf{Link} & \textbf{Default Cost} \\ \hline
10 Gbps & 1 \\ \hline 10 Gbps & 1 \\ \hline
1 Gbps & 4 \\ \hline 1 Gbps & 4 \\ \hline
100 Mbps & 19 \\ \hline 100 Mbps & 19 \\ \hline
10 Mbps & 100 \\ \hline 10 Mbps & 100 \\ \hline
\end{tabular}% \end{tabular}%
} }
\end{table} \end{table}
\fig{spanningtree/portroles}{stpportroles}{Port Election} \fig{spanningtree/portroles}{stpportroles}{Port Election}
@ -266,7 +266,7 @@ Cisco did on their part early on enhance the original spanning tree standard wit
\subsection{Link} \subsection{Link}
\begin{itemize} \begin{itemize}
\item Unidirectional Link Detection (UDLD) \item Unidirectional Link Detection (UDLD)
\begin{itemize} \begin{itemize}
\item Cisco proprietary feature. \item Cisco proprietary feature.
\item By default only enables on fiber optic links. \item By default only enables on fiber optic links.
@ -275,7 +275,17 @@ Cisco did on their part early on enhance the original spanning tree standard wit
\item On ether-channel links with uni-directional link failures, udld will disable individual failed links. \item On ether-channel links with uni-directional link failures, udld will disable individual failed links.
\item For the best protection. Aggresive mode is recommended. \item For the best protection. Aggresive mode is recommended.
\item It is recommended to turn on udld in global conf mode. \item It is recommended to turn on udld in global conf mode.
\item FlexLinks \item FlexLinks
\begin{itemize}
\item Cisco proprietary feature.
\item An alternate solution to running STP in the environment.
\begin{itemize}
\item STP is auto-disabled on interfaces running FlexLinks.
\item Configured with 2 physical links with and active/backup configuration.
\item Enables convergence time of less than 50 milliseconds.
\end{itemize}
\item FlexLinks is good alternative to running STP in an environment with customers who you do \texit{not} want to run STP with. Fx. Service Provider/Enterprise/Datacenter environment.
\end{itemize}
\end{itemize} \end{itemize}
\begin{table}[h] \begin{table}[h]