Switch Management and Operating Concepts
STP Parameters for the Switch Level
The following are the
Parameter | Description | Default Value | |
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| Specifies the combination of the |
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| the switch’s MAC address. The bridge identifier |
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Bridge Identifier | consists of two parts: a | 32768 + MAC address | |
| Ethernet MAC address. The only portion that a user |
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| can configure is the priority. |
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| Specifies the relative priority for each switch. Lower |
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Priority | numbers specify a higher priority and a greater chance | 32768 | |
| of a given switch being elected as the root bridge |
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| Specifies the length of time between broadcasts of the |
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| hello message by the switch. It can be set from 1 — 10 |
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Hello Time | seconds. This interval is not used until the switch | 2 seconds | |
becomes (if ever) the root bridge. | |||
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| The Hello Time parameter cannot be longer than the |
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| Max Age parameter. |
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| Measures the age of a received BPDU for a port, and |
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Max Age | ensures that the BPDU is discarded when its age | 20 seconds | |
exceeds the value of the Max Age parameter. | |||
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| It can be set from 6 — 40 seconds. |
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| Specifies the time a port can remaining in the listening |
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Forward Delay | state while moving from the blocking state to the | 15 seconds | |
forwarding state. | |||
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| It can be set from 4 — 30 seconds. |
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Use the following formulas when setting these parameters:
•Max Age = 2 x (Forward Delay
•Mag Age = 2 x (Hello Time + 1 second)
STP Parameters for the Port Level
The following are the
Variable | Description | Default Value | |
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| A relative priority for each port. Lower numbers specify |
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Port Priority | a higher priority and a greater chance of a given port | 32768 | |
| being elected as the root port |
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| • 100 for 10 Mbps Fast | |
| A value used by STP to evaluate paths. STP calculates | Etherenet ports | |
| • 19 for 100 Mbps Fast | ||
Port Cost | path costs and selects the path with the minimum cost | ||
Ethernet ports | |||
| as the active path. | ||
| • 4 for 1000 Mbps Gigabit | ||
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| Ethernet ports | |
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ZT8101 User’s Manual | 29 |