DGS-3700-12/DGS-3700-12G Series Layer 2 Gigabit Ethernet Switch User Manual
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STP Port Settings
This window is used to configure the STP Port Settings on the Swtich. STP can be set up on a port per port basis.
To view this window, click L2 Features > Spanning Tree > STP Port Settings as shown below:
Figure 3 - 58 STP Port Settings window
In addition to setting Spanning Tree parameters for use on the s witch level, t he Switch a llows for the c onfiguration of
groups of ports, each port-group of which will have its own spanni ng tree, and will require some of its own
configuration settings. An STP Group will use the switch-level param eters entered above, with the ad dition of Port
Priority and Port Cost.
An STP Group spanning tree works in the same way as the switch-level spanning tree, but the root brid ge concept is
replaced with a root port concept. A root port is a port of the grou p that is elected bas ed on por t prior it y and por t cost ,
to be the connection to the network for the group. Redundant links will be blocked, just as redundant link s are block ed
on the switch level.
The STP on the switch level blocks redundant links between switches (and similar network devices). T he port level
STP will block redundant links within an STP Group.
It is advisable to define an STP Group to correspond to a VLAN group of ports.
The following fields can be set:
Parameter Description
From Port / To Port A consecutive group of ports may be configured starting with the selected port.
External Cost (0=Auto) The external cost defines a metric that indicates the relative c ost of forward ing packets to
the specified port list. Port cost can be set automatically or as a metric value. The d efault
value is 0 (auto).
0 (auto) – Setting 0 for the extern al cost will automatically set the s peed for 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 external
cost. The lower the number, the greater the probability the port will be chosen to forward
packets.