Configuring Spanning Tree Protocol (STP) and IronSpan Features
December 2005
© Foundry Networks, Inc.
7 - 45
Disabling or Enabling 802.1W on an Individual Port
The
spanning-tree 802-1w
or
spanning-tree single 802-1w
command must be used to initially enable 802.1W
on ports. Both commands enable 802.1W on all ports that belong to the VLAN or to the single spanning tree.
Once 802.1W is enabled on a port, it can be disabled on individual ports. 802.1W that have been disabled on
individual ports can then be enabled as required.
NOTE:
If you change the 802.1W state of the primary port in a trunk group, the change affects all ports in that
trunk group.
To disable or enable 802.1W on an individual port, enter commands such as the following:
FESX424 Router(config)# interface e 1
FESX424 Router(config-if-e1000-1)# no spanning-tree
Syntax:
[no] spanning-tree
Changing 802.1W Bridge Parameters
When you make changes to 802.1W bridge parameters, the changes are applied to individual ports on the bridge.
To change 802.1W bridge parameters, use the following methods.
To designate a priority for a bridge, enter a command such as the following:
FESX424 Router(config)# spanning-tree 802-1w priority 10
The command in this example changes the priority on a device on which you have not configured port-based
VLANs. The change applies to the default VLAN. If you have configured a port-based VLAN on the device, you
can configure the parameters only at the configuration level for individual VLANs. Enter commands such as the
following:
FESX424 Router(config)# vlan 20
FESX424 Router(config-vlan-20)# spanning-tree 802-1w priority 0
To make this change in the default VLAN, enter the following commands:
FESX424 Router(config)# vlan 1
FESX424 Router(config-vlan-1)# spanning-tree 802-1w priority 0
Syntax:
spanning-tree 802-1w [forward-delay <value>] | [hello-time <value>] | [max-age <time>] | [force-version
<value>] | [priority <value>]
The
forward-delay
<value> parameter specifies how long a port waits before it forwards an RST BPDU after a
topology change. This can be a value from 4 – 30 seconds. The default is 15 seconds.
The
hello-time
<value> parameter specifies the interval between two hello packets. This parameter can have a
value from 1 – 10 seconds. The default is 2 seconds; however, set this value to at least 4 seconds to provide
enough time for BPDUs to reach the root bridge before the timeout period expires on a non-root bridge port.
The
max-age
<value> parameter specifies the amount of time the device waits to receive a hello packet before it
initiates a topology change. You can specify a value from 6 – 40 seconds. The default is 20 seconds.
The value of
max-age
must be greater than the value of
forward-delay
to ensure that the downstream bridges do
not age out faster than the upstream bridges (those bridges that are closer to the root bridge).
The
force-version
<value> parameter forces the bridge to send BPDUs in a specific format. You can specify one
of the following values:
•
0 – The STP compatibility mode. Only STP (or legacy) BPDUs will be sent.
•
2 – The default. RST BPDUs will be sent unless a legacy bridge is detected. If a legacy bridge is detected,
STP BPDUs will be sent instead.
The default is 2.
The
priority
<value> parameter specifies the priority of the bridge. You can enter a value from 0 – 65535. A lower
numerical value means a the bridge has a higher priority. Thus, the highest priority is 0. The default is 32768.
Содержание FastIron Edge Switch X424
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