Command Reference Guide

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Spanning Tree port configuration
By default for STP/PVST+, Spanning tree is turned Off for downlink ports (1-16), and turned On for uplink
ports (18-21). By default for RSTP/MSTP, Spanning tree is turned Off for all downlink ports (1-16) configured
as Edge ports, and turned On for uplink ports (18-21).
Spanning tree port parameters are used to modify STP operation on an individual port basis. STP port
parameters include:
Port priority
Port path cost
The following table describes the Spanning Tree Port Configuration commands.
Table 111 Spanning Tree Port Configuration commands
Command
Description
spanning-tree stp <1-128> priority
<0-255>
Configures the port priority. The port priority helps
determine which bridge port becomes the designated
port.
In a network topology that has multiple bridge ports
connected to a single segment, the port with the lowest
port priority becomes the designated port for the
segment.
The range is 0 to 255, and the default is 128.
RSTP/MSTP: The range is 0 to 240, in steps of 16 (0, 16, 32...)
and the default is 128.
Command mode: Interface port
spanning-tree stp <1-128> path-cost
<0-200000000>
Configures the port path cost. The port path cost is used to
help determine the designated port for a segment.
Generally speaking, the faster the port, the lower the path
cost.
The range is 0 to 65535. The default is 2 for 10Gb ports
except Port 17. A value of 0 indicates that the default cost
will be computed for an auto-negotiated link speed.
RSTP/MSTP: The range is 0 – 200000000, and the default is
2000 for 10 Gb ports except Port 17.
Command mode: Interface port
spanning-tree stp <1-128> link
{auto|p2p|shared}
Defines the type of link connected to the port, as follows:
auto: Configures the port to detect the link type, and
automatically match its settings.
p2p: Configures the port for Point-To-Point protocol.
shared: Configures the port to connect to a shared
medium (usually a hub).
This command only applies when RSTP is turned on.
Command mode: Interface port
[no] spanning-tree stp <1-128> edge
Enables or disables this port as an edge port. An edge port
is not connected to a bridge, and can begin forwarding
traffic as soon as the link is up. Configure server ports as
edge ports (enabled). By default, Ports 1-16 are
configured as edge ports.
This command only applies when RSTP is turned on.
Command mode: Interface port
[no] spanning-tree stp <1-128>
fastforward
Enables or disables Port Fast Forward on the port. The
default is disabled.
Command mode: Interface port
spanning-tree stp <1-128> enable
Enables STP on the port. This is the default for Ports 18-21.
Command mode: Interface port
no spanning-tree stp <1-128> enable
Disables STP on the port.
Command mode: Interface port