GE ML1200 instruction manual Path cost defined in Ieee 802.1d and 802.1w

RAPID SPANNING TREE PROTOCOL CHAPTER 13: RAPID SPANNING TREE PROTOCOL

The port specific values for RSTP or STP are shown below.

ZClick on the edit icon ( ) to edit the values for a specific port.

The columns in the above window are defined as follows:

• Port#: Indicates the port number. Value ranges from 1 to the maximum number of ports in the switch.

• Port Type: Indicates the type of port and speed; TP indicates twisted-pair.

• Port State: Forwarding implies traffic is forwarded onto the next switch or device connected the port. Disabled implies that the port may be turned off or the device connected to it may be unplugged or turned off. Values can be Listening, Learning, Forwarding, Blocking and Disabled.

• Path Cost: This is the assigned port cost value used for the switch to determine the forwarding points. Values range from 1 to 2000000. The lower the value, the lower the cost and hence the preferred route. The costs for different Ethernet speeds are shown below. The STP path cost is compared to the RSTP path cost.

Table 13–2: Path cost defined in IEEE 802.1d and 802.1w

Port Type	STP Path cost	RSTP Path cost
10 Mbps	100	2 000 000
100 Mbps	19	200 000
1 Gbps	4	20 000
10 Gbps	2	2000

• Priority: STP uses this to determine which ports are used for forwarding. Lower the number means higher priority. Value ranges from 0 to 255. Default is 128

• Edge Ports: RSTP offers edge port recognition, allowing ports at the edge of the network to forward frames immediately after activation while at the same time protecting them against loops.

13–18 MULTILINK ML1200 MANAGED FIELD SWITCH – INSTRUCTION MANUAL