GE ML1200 Path cost as defined in Ieee 802.1d / 802.1w, Forceversion stprstp, Show-forceversion

CHAPTER 13: RAPID SPANNING TREE PROTOCOL RAPID SPANNING TREE PROTOCOL

Example 13-3: RSTP information from a network with multiple switches

ML1200(rstp)##show stp ports

RSTP	Port Configuration
-------------------------------------------------------------------------------
Port#	Type	Priority	Path Cost	State	Des. Bridge	Des. Port
-------------------------------------------------------------------------------
01	TP(10/100)	128	200000	Forwarding	80:00:00:20:06:30:00:01	00:01
02	TP(10/100)	128	2000000	Disabled		00:02
03	100MB Fiber	128	200000	Disabled		00:03
04	100MB Fiber	128	200000	Disabled		00:04
05	100MB Fiber	128	200000	Disabled		00:05

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

Table 13–1: Path cost as defined in IEEE 802.1d / 802.1w

Port type	STP path cost	RSTP path cost
10 Mbps	100	2000000
100 Mbps	19	200000
1 Gbps	4	20000
10 Gbps	2	2000

•State: Indicates the STP state of individual ports. Values can be Listening, Learning, Forwarding, Blocking and Disabled.

•Des. Bridge: This is the port's designated root bridge

•Des. Port: This is the port's designated root port

Another example of the same command, from a larger network with several switches is shown in Example 13-3. Note the show stp ports command can be executed from the manager level prompt or from RSTP configuration state as shown in the screen captures earlier

In this example, ports 9 and 10 have a path cost of 20000 and are the least cost paths. These ports are connected to other switches and the ports are enabled as forwarding ports. Ports 6 and 7 are also connected to other switches. From the state column, it indicates that port 7 is in a standby state as that port is discarding all traffic.

More CLI commands associated with RSTP in the RSTP configuration mode are shown below. The forceversion command sets the STP or RSTP compatibility mode.

forceversion <stprstp>

The show-forceversioncommand displays the current forced version.

show-forceversion

MULTILINK ML1200 MANAGED FIELD SWITCH – INSTRUCTION MANUAL 13–7