ZyXEL Communications XS-3900-48F User Manual page 120

Chapter 11 Spanning Tree Protocol
The following table describes the labels in this screen.
Table 38 Advanced Application > Spanning Tree Protocol > MSTP
LABEL
Status
Active
Hello Time
MaxAge
Forwarding Delay
Maximum hops
Configuration
Name
Revision Number
Apply
Cancel
Instance
Instance
Bridge Priority
VLAN Range
120
DESCRIPTION
Click Status to display the MSTP Status screen (see
Select this check box to activate MSTP on the Switch. Clear this checkbox to disable MSTP
on the Switch.
Note: You must also activate Multiple Spanning Tree in the Advanced Application >
Spanning Tree Protocol > Configuration screen to enable MSTP on the Switch.
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:
Note: 2 * (Forward Delay - 1) >= Max Age >= 2 * (Hello Time + 1)
Enter the number of hops (between 1 and 255) in an MSTP region before the BPDU is
discarded and the port information is aged.
Enter a descriptive name (up to 32 characters) of an MST region.
Enter a number to identify a region's configuration. Devices must have the same revision
number to belong to the same region.
Click Apply to save your changes to the Switch's run-time memory. The Switch loses
these changes if it is turned off or loses power, so use the Save link on the top navigation
panel to save your changes to the non-volatile memory when you are done configuring.
Click Cancel to begin configuring this screen afresh.
Use this section to configure MSTI (Multiple Spanning Tree Instance) settings.
Enter the number you want to use to identify this MST instance on the Switch. The Switch
supports instance numbers 0-16.
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).
Enter the start of the VLAN ID range that you want to add or remove from the VLAN range
edit area in the Start field. Enter the end of the VLAN ID range that you want to add or
remove from the VLAN range edit area in the End field.
Next click:
• Add - to add this range of VLAN(s) to be mapped to the MST instance.
• Remove - to remove this range of VLAN(s) from being mapped to the MST instance.
• Clear - to remove all VLAN(s) from being mapped to this MST instance.
Figure 60 on page 123).
XS3900-48F User's Guide