ZyXEL Communications ES-4124 manual 120

Chapter 11 Spanning Tree Protocol

Table 28 Advanced Application > Spanning Tree Protocol > MRSTP (continued)

LABEL	DESCRIPTION
Active	Select this check box to activate an STP tree. Clear this checkbox to disable an
	STP tree.

	Note: You must also activate Multiple Rapid Spanning Tree in the
	Advanced Application > Spanning Tree Protocol >
	Configuration screen to enable MRSTP 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) 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 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 the 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.
Tree	Select which STP tree configuration this port should participate in.

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	ES-4124 User’s Guide