ZyXEL Communications MSC1024G Series User Manual page 486

Chapter 15 Switch Screens
Table 249 MSTP: Bridge (continued)
LABEL
Enable
Priority
Hello Time
MaxAge
Forwarding Delay
Force Version
MaxHops
MSTI
Priority
Apply
Cancel
MSTID
Start VID
End VID
Apply
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DESCRIPTION
Select this option to activate MSTP on the system.
Priority is used in determining the root switch. The switch with the highest priority
(lowest numeric value) becomes the STP root switch. If all switches have the
same priority, the switch with the lowest MAC address will then become the root
switch. Enter a number between 0 and 65535. The system will automatically
round the number to the nearest multiple of 4096.
The lower the numeric value you assign, the higher the priority for this switch.
Bridge Priority determines the root bridge, which in turn determines Hello Time,
Max Age and Forwarding Delay.
This is the time interval in seconds between BPDU (Bridge Protocol Data Units)
configuration message generations by the root switch. The allowed range is 1 to
10 seconds.
This is the maximum time (in seconds) a switch can wait without receiving a
BPDU before attempting to reconfigure. All switch ports (except for designated
ports) should receive BPDUs at regular intervals. Any port that ages out STP
information (provided in the last BPDU) becomes the designated port for the
attached LAN. If it is a root port, a new root port is selected from among the switch
ports attached to the network. The allowed range is 6 to 40 seconds.
This is the maximum time (in seconds) a switch will wait before changing states.
This delay is required because every switch must receive information about
topology changes before it starts to forward frames. In addition, each port needs
time to listen for conflicting information that would make it return to a blocking
state; otherwise, temporary data loops might result. The allowed range is 4 to 30
seconds. As a general rule:
2 * (Forward Delay - 1) >= Max Age >= 2 * (Hello Time + 1)
Specify a spanning tree protocol (MSTP or RSTP) the switch is to use.
Select MSTP to configure multiple spanning trees that allows a loop-free network
for one or more VLANs. Only MSTP BPDUs will be sent.
Select RSTP to send RSTP BPDUs and ignore any MSTP-specific information.
Enter the number of hops (between 1 and 255) in an MSTP region before the
BPDU is discarded and the port information is aged.
This field displays the MST instance number. The switch can identifies up to 16
spanning trees in a region.
Set the priority of the switch for the specific spanning tree instance. The lower the
number, the more likely the switch will be chosen as the root bridge within the
spanning tree instance.
Enter priority values between 0 and 61440 in increments of 4096 (thus valid
values are 4096, 8192, 12288, 16384, 20480, 24576, 28672, 32768, 36864,
40960, 45056, 49152, 53248, 57344 and 61440).
Click Apply to save the changes in this screen to the system's volatile memory.
The system loses these changes if it is turned off or loses power, so use the
Config Save on the navigation panel and then the Save button to save your
changes to the non-volatile memory when you are done configuring.
Click Cancel to start configuring this screen again.
Enter the ID number (0 ~ 16) of a spanning tress to which you want to map the
VLAN ID settings below.
Enter the start of the VLAN ID range to map to the MST instance.
Enter the end of the VLAN ID range to map to the MST instance. To map only one
VLAN, enter the same VID as the start VID.
Click Apply to add the VLAN-to-MST instance mapping. The new settings
automatically displays in the tables below.
MSC1000G/1024G/1224G Series User's Guide