D-Link xStack DES-3800 Series User Manual - Stp Port Settings
xStack DES-3800 Series Layer 3 Stackable Fast Ethernet Managed Switch
STP Port Settings
Figure 7- 30. STP Port Settings window
The following STP Port Settings fields can be set:
Parameter Description
From/To
A consecutive group of ports may be configured starting with the selected port.
External Cost
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 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.
Hello Time
The time interval between transmissions of configuration messages by the designated port, to
other devices on the bridged LAN. The user may choose a time between 1 and 10 seconds.
The default is 2 seconds. This field is only operable when the Switch is enabled for MSTP.
Migrate
When operating in RSTP mode, selecting yes forces the port that has been selected to
transmit RSTP BPDUs.
STP can be set up on a port per port basis.
To view the STP Port Settings window
click L2 Features > Spanning Tree >
STP Port Settings.
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.
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