another can be filtered from the network. The entry may specified as a source, a destination, or both (switch must be in IP Routing mode).
Spanning Tree
The IEEE 802.1D Spanning Tree Protocol allows for the blocking of links between switches that form loops within the network. When multiple links between switches are detected, a primary link is established. Duplicated links are blocked from use and become standby links. The protocol allows for the duplicate links to be used in the event of a failure of the primary link. Once the Spanning Tree Protocol 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.
The
On the switch level, STP calculates the Bridge Identifier for each switch and then sets the Root Bridge and the Designated Bridges.
On the port level, STP sets the Root Port and the Designated Ports.
The following are the
ameter |
| Description |
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| Default | |
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| Value |
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Bridge Identifier | A combination of the User- | 32768 + MAC | ||||
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| set priority and the switch’s |
| |||
(Not | user- | MAC address. | The | Bridge |
| |
configurable | Identifier | consists | of two |
| ||
except by setting | parts: a |
| ||||
priority below) | a |
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| address |
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Priority |
| A relative priority for each | 32768 | |||
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| switch – lower numbers give |
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| a higher priority and a |
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| greater chance of a given |
| |||
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| switch being elected as the |
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| root bridge |
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Hello Time |
| The length of time between | 2 seconds | |||
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| broadcasts | of | the | hello |
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| message by the switch |
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Maximum | Age | Measures the age of a | 20 seconds | |||
Timer |
| received BPDU for a port |
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| and ensures that the BPDU |
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| is discarded when its age |
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| exceeds the value of the |
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| maximum age timer. |
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Forward | Delay | The amount time spent by a | 15 seconds | |||
Timer |
| port in the learning and |
| |||
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| listening states waiting for a |
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30