User`s manual

Configuring the Spanning Tree Protocol
Web version
The Switch implements the IEEE Spanning Tree Protocol to detect and preserve an active bridged local area
network topology.
Spanning tree blocks certain ports to prevent bandwidth-sapping traffic loops while preserving fault tolerance by
maintaining a redundant bridge path as backup. If the first bridge path should fail, the secondary bridge path
takes over.
You can enable the spanning tree on one, several or all ports on the Switch.
Bridge configuration
Select Spanning Tree from the Main Menu to display this screen:
Information appears both for the Switch, shown under This Bridge, and the protocol's Root Bridge.
MAC Address is a read-only field showing each device's MAC address.
Root Path Cost is a read-only field showing the cost of the path to the root from this bridge. It is the sum
of the designated cost and path cost parameters specified for the root port. When the bridge is the root, as
shown in this sample screen, this number is 0.
1.
Click Enable Spanning Tree to enable the protocol on the Switch.2.
Enter a value from 0-65535 in the Priority field to influence the choice of this Switch as the root bridge of
the spanning tree. The lower the number, the more likely this port is used as the root. A 0 means that the
Switch is always the root of the tree.
3.
In Max Age, enter the time period after which received protocol information is discarded. The Switch
stores received and calculated BPDU parameters in memory. The stored configuration information for
each port is discarded if no update activity has occurred when this limit is reached. Maximum age can
range from 600-4000 in 10ms units (6-40 seconds in 1/100-second increments).
4.
In Hello Time, enter the time interval between issuing configuration Bridge Protocol Data Units (BPDU).
Bridges (switches) use BPDUs to calculate the spanning tree. Hello time can range from 100-1000 in
10ms units (1-10 seconds in 1/100-second increments). It is usually sufficient to use a whole number.
5.
In Forward Delay, enter the amount of time the spanning tree algorithm spends in each intermediate port
state during a transition from blocking to forwarding. The default is 15 seconds. This value is also used as
a short aging time value for all dynamic MAC entries in the address tables, during a topology change of
the active bridged local area network, as specified by the root bridge. Forward delay can range from
6.
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