D-Link xStack DGS-3426P, User Manual

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xStack DGS-3400 Series Layer 2 Gigabit Ethernet Managed Switch
STP Port Settings
Figure 7- 43. STP Port Settings window
It is advisable to define an STP Group to correspond to a VLAN group of ports.
The following STP Port Settings fields can be set:
Parameter Description
Unit Select the switch in the switch stack to be modified.
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.
Migration When operating in RSTP mode, selecting yes forces the port that has been selected to
transmit RSTP BPDUs.
Edge Choosing the True parameter designates the port as an edge port. Edge ports cannot create
loops, however an edge port can lose edge port status if a topology change creates a poten-
tial for a loop. An edge port normally should not receive BPDU packets. If a BPDU packet is
received, it automatically loses edge port status. Choosing the False parameter indicates that
the port does not have edge port status.
P2P Choosing the True parameter indicates a point-to-point (P2P) shared link. P2P ports are
similar to edge ports, however they are restricted in that a P2P port must operate in full
duplex. Like edge ports, P2P ports transition to a forwarding state rapidly thus benefiting
STP can be set up on a port per port basis. To
view the STP Port Settings window click
Layer
2 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.
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