ZyXEL ES-3148 Guida Utente

Chapter 11 Spanning Tree Protocol

ES-3148 User’s Guide

Click Advanced Application > Spanning Tree Protocol in the navigation panel to display 
the status screen as shown next. See 

 for more information on 

MRSTP. 

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 

 for more 

information.

Tree

Select which STP tree configuration this port should participate in.

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.

Table 29   Advanced Application > Spanning Tree Protocol > MRSTP  (continued)