D-Link xStack DGS-3426P User Manual - Stp Port Settings

xStack DGS-3400 Series Layer 2 Gigabit Ethernet Managed Switch 

STP Port Settings 

                                                                    Figure 7- 47. STP Port Settings window 

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. 

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 

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