Foundry NetIron M2404C and M2404F Metro Access Switches
Configuring RSTP (Rev. 03)
Rapid Spanning Tree Protocol (RSTP)
© 2008 Foundry Networks, Inc.
Page 18 of 34
point-to-point
Indicates that the configured interface is connected to one device, which
runs RSTP.
shared
Indicates that the interface is not connected to a single switch that is running
RSTP.
Setting RSTP Interface Path-Cost
The
rapid-spanning-tree path-cost
command, in Interface Configuration mode, sets the RSTP
port path-cost for the configured interface. The
no
form of this command resets the default path-
cost.
The user can use the path-cost value to give priority to links that provide better physical speed,
bandwidth etc. When building the active spanning tree, the interfaces path cost will determine
which ports will be included in the active topology. Interfaces with lower-cost values are preferred
to interfaces with higher cost values. If all interfaces that provide redundant paths to the root bridge
have the same cost value, RSTP puts the interface with the lowest interface number in the
forwarding state and blocks the other interfaces.
Table 4
shows the default RSTP path cost values.
Command Syntax
device-name
(config-if
UU/SS/PP
)#
rapid-spanning-tree path-cost
<
path-cost
>
device-name
(config-if
UU/SS/PP
)#
no rapid-spanning-tree path-cost
Argument Description
path-cost
RSTP path-cost value, in range <1-200000000>, which is assigned to the
configured interface.
Setting RSTP Port Priority
The
rapid-spanning-tree priority
command, in Interface Configuration mode, sets the RSTP
priority for the configured interface. The
no
form of this command resets the priority to the default
value.
If a loop occurs, RSTP uses the port priority when selecting an interface to put into the forwarding
state. Assign high priority values (low numerical values) to interfaces that the user wants to be
selected first, and low priority values (high numerical values) to interfaces that the user wants
selected last. If all interfaces that connect to redundant paths to the root bridge have the same
priority value, RSTP puts the interface with the lowest interface number in the forwarding state and
blocks the other interfaces.
By default, the priority value is 128.
Command Syntax
device-name
(config-if
UU/SS/PP
)#
rapid-spanning-tree priority
<
priority
>
device-name
(config-if
UU/SS/PP
)#
no rapid-spanning-tree priority