91
•
legacy
—Compatible format
By default, the packet format recognition mode of a port is
auto
. The port automatically distinguishes
the two MSTP packet formats, and determines the format of packets that it will send based on the
recognized format.
You can configure the MSTP packet format on a port. Then, the port sends only MSTP packets of the
configured format to communicate with devices that send packets of the same format.
By default, a port in
auto
mode sends 802.1s MSTP packets. When the port receives an MSTP
packet of a legacy format, the port starts to send packets only of the legacy format. This prevents the
port from frequently changing the format of sent packets. To configure the port to send 802.1s MSTP
packets, shut down and then bring up the port.
When the number of existing MSTIs exceeds 48, the port can send only 802.1s MSTP packets.
To configure the MSTP packet format to be supported on a port:
Step Command Remarks
1.
Enter system view.
system-view
N/A
2.
Enter Layer 2 Ethernet or
aggregate interface view.
interface interface-type
interface-number
N/A
3.
Configure the mode that the
port uses to recognize/send
MSTP packets.
stp compliance
{
auto
|
dot1s
|
legacy
}
The default setting is
auto
.
Enabling outputting port state transition
information
In a large-scale spanning tree network, you can enable devices to output the port state transition
information. Then you can monitor the port states in real time.
To enable outputting port state transition information:
Step Command
Remarks
1.
Enter system view.
system-view
N/A
2.
Enable outputting port
state transition
information.
•
In
STP/RSTP
mode:
stp port-log instance 0
•
In PVST mode:
stp port-log
vlan
vlan-id-list
•
In
MSTP
mode:
stp port-log
{
all
|
instance
instance-list
}
By default, this function is
disabled.
Enabling the spanning tree feature
You must enable the spanning tree feature for the device before any other spanning tree related
configurations can take effect. In STP, RSTP, or MSTP mode, make sure the spanning tree feature is
enabled globally and on the desired ports. In PVST mode, make sure the spanning tree feature is
enabled globally, in the desired VLANs, and on the desired ports.
You can disable the spanning tree feature for certain ports with the
undo stp enable
command to
exclude them from spanning tree calculation and save CPU resources of the device. Make sure no
loops occur in the network after you disable the spanning tree feature on these ports.
