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FL SWITCH MM HS
5-22
PHOENIX CONTACT
6874_en_16
Selecting a root port
Once the root switch has been specified by processing the root IDs, the switches now
specify the root ports.
The most favorable path is specified by minimizing all connection costs on the path to the
root switch. In addition, transmission speeds can also serve as costs. For the switch, the
path costs added by each port for every HOP (the hop of a data packet from one point to the
next) are preset to a value of 19 (default setting/recommended for 100 Mbps) and can be
modified at any time by the user.
Selecting a designated port
At every "designated switch" the port with the most cost-effective data link in the direction
of the root switch is called the designated port.
Port costs
The port costs can be set according to two different standards, 802.1D (STP) or 801.1W
(RSTP).
If, in addition to Phoenix Contact devices, devices from other manufacturers are also
used, it is recommended that the port costs are set according to a uniform standard.
The "dot1dstpPathCostDefault" SNMP object (OID 1.3.6.1.2.1.17.2.18) can be used to
change the standard that is used.
Table 5-2
Port costs according to 802.D
Transmission speed
Recommended value
Recommended range
10 Mbps
100
50 - 600
100 Mbps
19
10 - 60
Table 5-3
Port costs according to 802.W
Transmission speed
Recommended value
Recommended range
10 Mbps
2,000,000
200,000 - 20,000,000
100 Mbps
200,000
20,000 - 2,000,000
RSPSupply - 1-888-532-2706 - www.RSPSupply.com
http://www.RSPSupply.com/p-14178-Phoenix-Contact-2832357-FL-IF-2TX-VS-RJ-D-Media-Module-for-Modular-Switch.aspx