ZyXEL Communications GS1920-48HPv2, Руководство пользователя

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Chapter 13 Spanning Tree Protocol
GS1920v2 Series User’s Guide
140
The following table describes the labels in this screen.
Table 51 Advanced Application > Spanning Tree Protocol > RSTP
LABEL DESC RIPTIO N
Status Click
Sta tus
to display the
RSTP Sta tus
screen (see Figure 109 on page 141 ).
Active Select this check box to activate RSTP. Clear this checkbox to disable RSTP.
Note: You must also activate
Ra pid Spa nning Tre e
in the
Adva nc e d Applic a tio n >
Spa nning Tre e Pro to c o l > C o nfig ura tio n
screen to enable RSTP on the Switch.
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. Select a value from the drop-down list box.
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) the 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) the 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 displays the port number.
* Settings in this row apply to all ports.
Use this row only if you want to make some settings the same for all ports. Use this row first to set
the common settings and then make adjustments on a port-by-port basis.
Note: Changes in this row are copied to all the ports as soon as you make them.
Active Select this check box to activate RSTP on this port.
Edge Select this check box to configure a port as an edge port when it is directly attached to a
computer. An edge port changes its initial STP port state from blocking state to forwarding
state immediately without going through listening and learning states right after the port is
configured as an edge port or when its link status changes.
Note: An edge port becomes a non-edge port as soon as it receives a Bridge
Protocol Data Unit (BPDU).
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 the default value is 128.
Path Cost Path cost is the cost of transmitting a frame on to a LAN through that port. It is recommended
to assign this value according to the speed of the bridge. The slower the media, the higher the
cost - see
Table 48 on page 136 for more information.