ZyXEL Communications AAM1212-51, Руководство пользователя, Страница: 176 / 435

AAM1212-51/53 Series User’s Guide
176 Chapter 22 Spanning Tree Protocol
Bridge Priority Bridge priority is used in determining the root switch, root port and designated
port. 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. The allowed range is 0 to 61440.
The lower the numeric value you assign, the higher the priority for this bridge.
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.
MAX Age 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)
Port This field identifies the Ethernet port.
Active Select this check box to activate STP on this port.
Priority Configure the priority for each port here.
Priority decides which port should be disabled when more than one port forms a
loop in a switch. Ports with a higher priority numeric value are disabled first. The
allowed range is between 0 and 255 and default value is 128.
Path Cost Path cost is the cost of transmitting a frame on to a LAN through that port. It is
assigned according to the speed of the bridge. The slower the media, the higher
the cost.
Apply Click Apply to save your changes to the AAM1212’s volatile memory. The
AAM1212 loses these changes if it is turned off or loses power, so use the
Config Save link on the 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.
Table 51 Spanning Tree Protocol (continued)
LABEL DESCRIPTION