ZyXEL Communications ES-3148 Series User Manual
Page 121
Chapter 11 Spanning Tree Protocol
ES-3148 User’s Guide
121
The following table describes the labels in this screen.
Table 31 Advanced Application > Spanning Tree Protocol > MSTP
LABEL
DESCRIPTION
Status
Click Status to display the MSTP Status screen (see
).
Active
Select this to activate MSTP on the Switch. Clear this 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.
Hello Time
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.
MaxAge
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.
Forwarding Delay 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)
Maximum hops
Enter the number of hops (between 1 and 255) in an MSTP region before the
BPDU is discarded and the port information is aged.
Configuration
Name
Enter a descriptive name (up to 32 characters) of an MST region.
Revision Number
Enter a number to identify a region’s configuration. Devices must have the same
revision number to belong to the same region.
Apply
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.
Cancel
Click Cancel to begin configuring this screen afresh.
Instance
Use this section to configure MSTI (Multiple Spanning Tree Instance) settings.
Instance
Enter the number you want to use to identify this MST instance on the Switch. The
Switch supports instance numbers 0-16.
Bridge Priority
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).