Microsens MS453490M Management Guide - Manual (Page 198)

C HAPTER 8 | Spanning Tree Algorithm
Configuring Global Settings for STA
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connected to an 802.1D bridge and starts using only 802.1D
BPDUs.
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RSTP Mode – If RSTP is using 802.1D BPDUs on a port and receives
an RSTP BPDU after the migration delay expires, RSTP restarts the
migration delay timer and begins using RSTP BPDUs on that port.
◆ Multiple Spanning Tree Protocol
MSTP generates a unique spanning tree for each instance. This provides
multiple pathways across the network, thereby balancing the traffic
load, preventing wide-scale disruption when a bridge node in a single
instance fails, and allowing for faster convergence of a new topology for
the failed instance.
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To allow multiple spanning trees to operate over the network, you
must configure a related set of bridges with the same MSTP
configuration, allowing them to participate in a specific set of
spanning tree instances.
■
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.
P ARAMETERS
These parameters are displayed:
Basic Settings
◆ Spanning Tree Status – Enables/disables STA on this switch.
(Default: Enabled)
◆ Spanning Tree Type – Specifies the type of spanning tree used on
this switch:
■
STP: Spanning Tree Protocol (IEEE 802.1D); i.e., when this option
is selected, the switch will use RSTP set to STP forced compatibility
mode).
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RSTP: Rapid Spanning Tree (IEEE 802.1w); RSTP is the default.
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MSTP: Multiple Spanning Tree (IEEE 802.1s)
◆ 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.)
1. STP and RSTP BPDUs are transmitted as untagged frames, and will cross any VLAN
boundaries.