User manual

C HAPTER 4 | Configuring the Switch
Configuring the Spanning Tree Algorithm
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configuration, allowing them to participate in a specific set of
spanning tree instances.
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A spanning tree instance can exist only on bridges that have
compatible VLAN instance assignments.
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Be careful when switching between spanning tree modes. Changing
modes stops all spanning-tree instances for the previous mode and
restarts the system in the new mode, temporarily disrupting user
traffic.
PARAMETERS
These parameters are displayed:
Basic Settings
◆ Protocol Version – Specifies the type of spanning tree used on this
switch. (Options: STP, RSTP, MSTP; Default: MSTP)
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STP: Spanning Tree Protocol (IEEE 802.1D); i.e., the switch will use
RSTP set to STP forced compatibility mode.
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RSTP: Rapid Spanning Tree (IEEE 802.1w)
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MSTP: Multiple Spanning Tree (IEEE 802.1s); This is the default.
◆ Bridge Priority – Bridge priority is used in selecting the root device,
root port, and designated port. The device with the highest priority
becomes the STA root device. However, if all devices have the same
priority, the device with the lowest MAC address will then become the
root device. (Note that lower numeric values indicate higher priority.)
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Default: 128
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Range: 0-240, in steps of 16
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Options: 0, 16, 32, 48, 64, 80, 96, 112, 128, 144, 160, 176, 192,
208, 224, 240
◆ Forward Delay – The maximum time (in seconds) this device will wait
before changing states (i.e., discarding to learning to forwarding). This
delay is required because every device must receive information about
topology changes before it starts to forward frames. In addition, each
port needs time to listen for conflicting information that would make it
return to a discarding state; otherwise, temporary data loops might
result.
Minimum: The higher of 4 or [(Max. Message Age / 2) + 1]
Maximum: 30
Default: 15
◆ Max Age – The maximum time (in seconds) a device can wait without
receiving a configuration message before attempting to reconfigure. All
device ports (except for designated ports) should receive configuration
messages at regular intervals. Any port that ages out STA information
(provided in the last configuration message) becomes the designated
port for the attached LAN. If it is a root port, a new root port is selected