D-Link DES-6500 - Switch User Manual page 65

The following parameters may be viewed in the STP Instance Operational Status windows:
Parameter
Designated Root Bridge
External Root Cost
Regional Root Bridge
Internal Root Cost
Designated Bridge
Root Port
Max Age
Forward Delay
Last Topology Change
Topology Changes Count
xStack DES-6500 Modular Layer 3 Chassis Ethernet Switch User Manual
Description
This field will show the priority and MAC address of the Root Bridge.
This defines a metric that indicates the relative cost of forwarding packets to the
specified port list. Port cost can be set automatically or as a metric value. The default
value is 0 (auto).
0 (auto) - Setting 0 for the external cost will automatically set the speed for
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forwarding packets to the specified port(s) in the list for optimal efficiency. Default
port cost: 100Mbps port = 200000. Gigabit port = 20000.
value 1-200000000 - Define a value between 1 and 200000000 to determine the
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external cost. The lower the number, the greater the probability the port will be
chosen to forward packets.
This field will show the priority and MAC address of the Regional (Internal) Root Bridge.
This MAC address should be the MAC address of the Switch.
This parameter is set to represent the relative cost of forwarding packets to specified
ports when an interface is selected within a STP instance. The default setting is 0
(auto). There are two options:
0 (auto) - Selecting this parameter for the internalCost will set quickest route
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automatically and optimally for an interface. The default value is derived from the
media speed of the interface.
value 1-2000000 - Selecting this parameter with a value in the range of 1-2000000
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will set the quickest route when a loop occurs. A lower Internal cost represents a
quicker transmission.
This field will show the priority and MAC address of the Designated Bridge. The
information shown in this table comes from a BPDU packet originating from this bridge.
This is the port on the Switch that is physically connected to the Root Bridge.
The Max Age may be set to ensure that old information does not endlessly circulate
through redundant paths in the network, preventing the effective propagation of the new
information. Set by the Root Bridge, this value will aid in determining that the Switch has
spanning tree configuration values consistent with other devices on the bridged LAN. If
the value ages out and a BPDU has still not been received from the Root Bridge, the
Switch will start sending its own BPDU to all other switches for permission to become
the Root Bridge. If it turns out that your switch has the lowest Bridge Identifier, it will
become the Root Bridge. The user may choose a time between 6 and 40 seconds. The
default value is 20.
The Forward Delay can be from 4 to 30 seconds. Any port on the Switch spends this
time in the listening state while moving from the blocking state to the forwarding state.
This field shows the time, in seconds, since the last spanning tree topology change.
This field displays the number of times that the spanning tree topology has changed
since the original initial boot up of the Switch.
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