Port Roles Based On Spanning Tree; Spanning Tree Protocol Port States; Configuring Spanning Tree; All Rights Reserved, Copyright (C) Pfu Limited - Fujitsu XG2000 Series User Manual

XG2000 series User's Guide

4.6.1 Port Roles Based on Spanning Tree

RSTP assigns one of these port roles to individual ports:
Root port
Provides the best path (lowest cost) when the switch forwards packets to the root switch.
Designated port
Connects to the designated switch toward the leaves of the spanning tree. The port specified
connecting to the designated port serves as a root port.
Alternate Port
The alternative port with the second lowest path cost. In the event that the root port goes
to a linkdown state, the alternate port serves as the root port. It does not always send
or receive frames while in the blocking state.
Backup Port
Provides an alternative path to that specified. In the event that the specified port goes
into a linkdown state, the backup port serves as the new designated port. It does not always
send or receive frames while it is in the blocking state.
Disabled Port
Disabled port, it does not send or receive any frames.

4.6.2 Spanning Tree Protocol Port States

The port states defined by the STP are:
Discard
The port is in a "discarding state. BPDUs are only received.
Learn
The port is in a "learning" state. A port in the learning state learns the destination MAC
address of the received frames but does not participate in frame forwarding.
Forward
The port is ready to transmit data traffic.
The STP states "blocking" and "listening" have been merged into a unique RSTP "discarding" state. The correspondence
between STP port states and RSTP port states are shown below.

4.6.3 Configuring Spanning Tree

To configure the spanning tree protocol, carry out the following procedure in the administrator EXEC mode.
xg# configure terminal
xg(config)# spanning-tree
xg(config)# spanning-tree priority <0-61440>
xg(config)# spanning-tree hello-time <1-10>
xg(config)# spanning-tree max-age <6-40>
xg(config)# spanning-tree forward-time <4-30>
xg(config)# interface port 1 2 3
xg(config)# interface port range 1 3
xg(config-if)# spanning-tree port-priority
<0-240>
xg(config-if)# spanning-tree port-path-cost
<1-200000000>
xg(config-if)# spanning-tree portfast
xg(config-if)# exit
xg(config)# exit
xg# show spanning-tree [ detail ]
Display STP(IEEE802.1D)
Format
Discard Blocking
Discard Listening
Learn Learning
Forward Forwarding
Command

All Rights Reserved, Copyright (C) PFU LIMITED 2009

RSTP(IEEE802.1w)
Discarding
Discarding
Learning
Forwarding
Switch to global configuration mode.
Enable Spanning Tree Protocol.
Configure Spanning Tree Protocol parameters on the
device.
Switch priority
Hello time
Maximum aging time (max-age)
Forward delay time (forward-time)
Switch to interface edit mode to configure spanning
tree-related parameters for a given port.
In this example, the global interface configuration mode
is selected for ports 1 through 3.
Configure the following parameters related to the
spanning tree topology:
Port priority
Path cost
(Optional)
If the port is configured as an edge port(*), this setting
can reduce the time taken to transition into the
forwarding state.
* It is available only when the port is directly connected
to an end terminal that has no influence on the spanning
tree configuration.
Exit to global configuration mode.
Exit to administrator EXEC mode.
View the state of the spanning tree.
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