ZyXEL GS1500-24P User Guide - Page 76
Note: 2 * Forward Delay - 1 >= Max Age >= 2 * Hello Time + 1, Configuration > Spanning Tree
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Chapter 9 Spanning Tree Protocol Table 17 Configuration > Spanning Tree > STP Global Setting (continued) LABEL DESCRIPTION Priority 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 0~61440 from the drop-down list box. The lower the numeric value you assign, the higher the priority for this bridge. Maximum Age Hello Time Forwarding Delay Priority determines the root bridge, which in turn determines the Root Hello Time, Root Maximum Age and Root Forwarding Delay. 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. 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) 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) Root priority Root refers to the base of the spanning tree (the root bridge). This field displays the root bridge's priority. This Switch may also be the root bridge. Root MAC Address This is the MAC address of the root bridge. Root Path Cost This is the path cost from the root port on this Switch to the root switch. Root Port This is the number of the port on the Switch through which this Switch must communicate with the root of the Spanning Tree. Root Maximum This is the maximum time (in seconds) the Switch can wait without Age receiving a configuration message before attempting to reconfigure. Root Hello Time This is the time interval (in seconds) at which the root switch transmits a configuration message. The root bridge determines Hello Time, Max Age and Forwarding Delay. Root Forward Delay This is the time (in seconds) the root switch will wait before changing states. Topology Changes This is the number of times the spanning tree has been reconfigured. 76 GS1500-24P User's Guide