ZyXEL Communications ES-4124 manual 117

	Chapter 11 Spanning Tree Protocol
Table 26 Advanced Application > Spanning Tree Protocol > RSTP (continued)
LABEL	DESCRIPTION
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) 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 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.
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 23 on page 110 for more
	information.
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.

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ES-4124 User’s Guide