D-Link DGS-3700 user manual STP Port Settings, External Cost 0=Auto

DGS-3700-12/DGS-3700-12G Series Layer 2 Gigabit Ethernet Switch User Manual

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 switch level, the Switch allows for the configuration of groups of ports, each port-group of which will have its own spanning tree, and will require some of its own configuration settings. An STP Group will use the switch-level parameters entered above, with the addition 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 bridge concept is replaced with a root port concept. A root port is a port of the group that is elected based on port priority and port cost, to be the connection to the network for the group. Redundant links will be blocked, just as redundant links are blocked on the switch level.

The STP on the switch level blocks redundant links between switches (and similar network devices). The 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:

ParameterDescription

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 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 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.
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