CHAPTER 13: RAPID SPANNING TREE PROTOCOL
CONFIGURING RSTP THROUGH THE COMMAND LINE INTERFACE
MULTILINK ML1600 ETHERNET COMMUNICATIONS SWITCH – INSTRUCTION MANUAL
13–7
The variables listed by the
show stp ports
command are:
•
Port#
: Indicates the port number. The value ranges from 1 to the maximum
number of ports in the switch.
•
Type
: Indicates the type of port. TP indicates twisted pair.
•
Priority
: STP uses this to determine which ports are used for forwarding. Lower
numbers indicate higher priority. The values range from 0 to 255, with a default of
128.
•
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.
•
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.
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
Example 13-2: Reviewing the RSTP port parameters
ML1600(rstp)##
show stp ports
RSTP Port Configuration
--------------------------------------------------------------------------------------
Port#
Type
Priority
Path Cost
State
Des. Bridge
Des. Port
--------------------------------------------------------------------------------------
09
TP(10/100)
128
2000000
Forwarding
80:00:00:20:06:25:ed:89
80:09
10
TP(10/100)
128
2000000
Disabled
80:0a
11
TP(10/100)
128
2000000
Disabled
80:0b
12
TP(10/100)
128
2000000
Disabled
80:0c
13
TP(10/100)
20
200000
Forwarding
80:00:00:20:06:25:ed:89
80:0d
14
TP(10/100)
128
2000000
Disabled
80:0e
15
TP(10/100)
128
2000000
Disabled
80:0f
16
TP(10/100)
128
2000000
Disabled
80:10
ML1600(rstp)##