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Figure 5-35:  802.1Q VLAN interface 
 
 
•  Group Configuration 
Edit the existing VLAN Group. 
•  Select the VLAN group in the table list. 
•  Click  EDIT . 
Figure 5-36:  Group Configuration interface 
  

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• You can modify the VLAN group name and VLAN ID. 
Figure 5-37:  Group Configuration interface 
 
• Click  APPLY . 
Rapid Spanning Tree Protocol 
The Rapid Spanning Tree Protocol (RSTP) is  an evolution of the Spanning Tree Protocol 
and provides for faster spanning tree co nvergence after a topology change. The 
system also supports STP and the system w ill auto-detect the connected device that 
is running STP or RSTP...

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protocol allows for the duplicate links to  be used in the event of a failure of the 
primary link. Once the Spanning Tree Prot ocol is configured and enabled, primary 
links are established and duplicated links are blocked automatically. The reactivation 
of the blocked links (at the time of a  primary link failure) is also accomplished 
automatically without operator intervention. 
This automatic network reconfiguration...

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The communication between switches via BPDUs results in the following: 
• One switch is elected as the root switch. 
•  The shortest distance to the root sw itch is calculated for each switch. 
•  A designated switch is selected. This is  the switch closest to the root switch 
through which packets will be  forwarded to the root. 
•  A port for each switch is selected. This is  the port providing the best path from the...

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A port transitions from one  state to another as follows: 
•  From initialization (swi tch boot) to blocking. 
•  From blocking to list ening or to disabled. 
•  From listening to lear ning or to disabled. 
•  From learning to forwa rding or to disabled. 
•  From forwarding to disabled. 
•  From disabled to blocking. 
Figure 5-38: STP Port State Transitions 
 
You can modify each port state by usin g management software....

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RSTP Parameters 
RSTP Operation Levels 
The Switch allows for two levels of operation: the switch level and the port level. The 
switch level forms a spanning tree consisting  of links between one or more switches. 
The port level constructs a s panning tree consisting of groups of one or more ports. 
The STP operates in much the same way for both levels. 
NOTE:  On the switch level, RSTP calculates th e Bridge Identifier...

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The following are the user-configurable ST P parameters for the port or port group 
level: 
 
Variable Description Default Value 
Port Priority  A relative priority for each port –lower  numbers give a higher priority and a 
greater chance of a given port being 
elected as the root port  128 
Port Cost  A value used by STP to evaluate paths 
– STP calculates path costs and selects 
the path with the minimum cost as the...

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NOTE: The Hello Time cannot be longer than th e Max. Age. Otherwise, a configuration 
error will occur. 
Max. Age – The Max Age can be from 6 to 40 seco nds. At the end of the Max Age, if a 
BPDU has still not been received from the Ro ot Bridge, your Switch will start sending 
its own BPDU to all other Switches for perm ission to become the Root Bridge. If it 
turns out that your Switch has the lowest Bridge Identifier,...

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the Priority setting, or influencing STP to  choose a particular port to block using the 
Port Priority and Port Cost settings is,  however, relatively straight forward. 
Figure 5-39: Before Applying the STA Rules 
 
In this example, only the default STP values are used. 
Figure 5-40: After Applying the STA Rules 
 
  

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The switch with the lowest Bridge ID (switch C) was elected the root bridge, and the 
ports were selected to give a high port  cost between switches B and C. The two 
(optional) Gigabit ports (defau lt port cost = 4) on switch A are connected to one 
(optional) Gigabit port on both switch B  and C. The redundant link between switch B 
and C is deliberately chosen as a 100 Mbps  Fast Ethernet link (default port cost = 19)....