D-Link xStack DGS-3400 Series Reference Manual page 220

x Stack
Unit
From / To
External Cost
(0=Auto)
Hello Time
Migrate
Edge
P2P
State
LBD
BPDU
Restricted Role
Restricted Tcn
®
DGS-3400 Series Layer 2 Gigabit Ethernet M anaged Sw itch
Select the switch in the switch stack to be modified.
A consecutive group of ports may be configured starting with the selected port.
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.
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. If the inputted Hello Time is greater than 2, the Hello
Time is 2. This field is only operable when the Switch is enabled for MSTP.
When operating in RSTP mode, selecting yes forces the port that has been selected to
transmit RSTP BPDUs.
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.
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
from RSTP. A p2p value of False indicates that the port cannot have p2p status. Auto allows
the port to have p2p status whenever possible and operate as if the p2p status were true. If
the port cannot maintain this status, (for example if the port is forced to half-duplex operation)
the p2p status changes to operate as if the p2p value were false. The default setting for this
parameter is true.
This drop-down menu allows you to enable or disable STP for the selected group of ports.
The default is Enabled.
Use the pull-down menu to enable or disable the loop-back detection function on the switch
for the ports configured above.
Use the pull-down menu to enable or disable the flooding of BPDU packets when STP is
disabled.
Toggle between True and False to set the restricted role state of the port. The default value
is False.
If True causes the port not to be selected as the root port for the CIST or any MSTI, even if it
has the best spanning tree priority vector, such a port will be selected as an Alternate Port
after the Root Port has been selected. This parameter should be False by default. Setting
this variable can cause lack of spanning tree connectivity. It is set by a network administrator
to prevent bridges external to a core region of the network influencing the spanning tree
active topology, possibly because those bridges are not under the full control of the
administrator.
Toggle between True and False to set the restricted TCN of the port. The default value is
False.
If True causes the port not to be selected as the root port for the CIST or any MSTI, even if it
has the best spanning tree priority vector, such a port will be selected as an Alternate Port
after the Root Port has been selected. This parameter should be False by default. Setting
this variable can cause lack of spanning tree connectivity. It is set by a network administrator
to prevent bridges external to a core region of the network influencing the spanning tree
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