90
•
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. When operating in MSTP mode after the
configuration, the port sends and receives only MSTP packets of the format that you have configured to
communicate with devices that send packets of the same format.
MSTP provides MSTP packet format incompatibility guard. In MSTP mode, if a port is configured to
recognize/send MSTP packets in a mode other than
auto
, and if it receives a packet in a format different
from the specified type, the port becomes a designated port and remains in the discarding state to
prevent the occurrence of a loop.
MSTP provides MSTP packet format frequent change guard. If a port receives MSTP packets of different
formats frequently, the MSTP packet format configuration contains errors. If the port is operating in MSTP
mode, it will be shut down for protection. Ports disabled in this way can be re-activated after a detection
interval. For more information about the detection interval, see
Fundamentals Configuration Guide
.
To configure the MSTP packet format to be supported on a port or a group of ports:
Step Command
Remarks
1.
Enter system view.
system-view
N/A
2.
Enter interface view or
port group view.
•
Enter Layer 2 Ethernet interface view or Layer 2
aggregate interface view:
interface
interface-type interface-number
•
Enter port group view:
port-group manual
port-group-name
Use one of the
commands.
3.
Configure the mode that
the port uses to
recognize/send MSTP
packets.
stp compliance
{
auto
|
dot1s
|
legacy
}
auto
by default.
Enabling outputting port state transition information
In a large-scale spanning tree network, you can enable devices to output the port state transition
information of all MSTIs or the specified MSTI in order to 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-list
•
In MSTP mode:
stp port-log instance
{
instance-id
|
all
}
Use one of the commands.
Enabled by default.
