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