H3C Technologies H3C SecPath F1000-E - Manual (Page 101)

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Item Description
mCheck
In a switched network, if a port on an MSTP device connects to an STP device, this
port will automatically migrate to the STP-compatible mode. However, after the STP
device is removed, whether the port on the MSTP device can migrate automatically
to the MSTP mode depends on which of the following parameter is selected:
• Enable—Perform mCheck. The port automatically migrates back to the MSTP
mode.
• Disable—Do not perform mCheck. The port does not automatically migrate
back to the MSTP mode.
Instance
Instance ID MSTI ID.
Port Priority
Priority of the port in the current MSTI.
The priority of a port is an import factor in determining whether the port can be
elected as the root port.
Path Cost Select to calculate the path cost automatically or set the path cost manually.
Table 19 Protection types
Protection type Description
Edged Port
Set the port as an edge port.
Some ports of access layer devices are directly connected to PCs or file servers,
which cannot generate BPDUs. You can set these ports as edge ports to achieve fast
transition for these ports.
H3C recommends that you enable the BPDU guard function in conjunction with the
edged port function to avoid network topology changes when the edge ports
receive configuration BPDUs.
Root Protection
Enable the root guard function.
Configuration errors or attacks may result in configuration BPDUs with their
priorities higher than that of a root bridge, which causes a new root bridge to be
elected and network topology change to occur. The root guard function is used to
address such a problem.
Loop Protection
Enable the loop guard function.
By keeping receiving BPDUs from the upstream device, a device can maintain the
state of the root port and other blocked ports. These BPDUs may get lost because of
network congestion or unidirectional link failures. The device will re-elect a root
port, and blocked ports may transit to the forwarding state, causing loops in the
network. The loop guard function is used to address such a problem.
MSTP configuration example
Network requirements
As shown in Figure 49 , all devices on the network are in the same MST region. SecPath and Device A
work on the distribution layer, and Device B and Device C work on the access layer.
Configure MSTP so that packets of different VLANs are forwarded along different spanning trees: Packets
of VLAN 10 are forwarded along MSTI 1, those of VLAN 30 are forwarded along MSTI 3, those of VLAN
40 are forwarded along MSTI 4, and those of VLAN 20 are forwarded along MSTI 0.