ZyXEL Communications MSC1000G Series, User Manual

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Chapter 13 Switch Screens
Management Switch Card User’s Guide
528
Enable Select this option to activate MSTP on the system.
Priority 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.
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:
2 * (Forward Delay - 1) >= Max Age >= 2 * (Hello Time + 1)
Force Version 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.
MaxHops Enter the number of hops (between 1 and 255) in an MSTP region before the BPDU is
discarded and the port information is aged.
MSTI This field displays the MST instance number. The switch can identifies up to 16 spanning trees
in a region.
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).
Apply 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 link on the
navigation panel and then the Save button to save your changes to the non-volatile memory
when you are done configuring.
Cancel Click Cancel to start configuring this screen again.
MSTID Enter the ID number (0 ~ 16) of a spanning tress to which you want to map the VLAN ID
settings below.
Start VID Enter the start of the VLAN ID range to map to the MST instance.
End VID 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.
Apply Click Apply to add the VLAN-to-MST instance mapping. The new settings automatically
displays in the tables below.
MSTID This field displays the ID of an MST instance.
Table 279
MSTP: Bridge (continued)
LABEL DESCRIPTION