Step Operation Description
1 Make clear roles the switches
play in spanning tree
instances: root bridge or
designated bridge
Preparation.
2 Globally configure MSTP
parameters
Required. Enable Spanning Tree function on the switch
and configure MSTP parameters on Spanning
Tree→STP Config→STP Config page.
3 Configure MSTP parameters
for ports
Required. Configure MSTP parameters for ports on
Spanning Tree→Port Config→Port Config page.
4 Configure the MST region Required. Create MST region and configure the role the
switch plays in the MST region on Spanning
Tree→MSTP Instance→Region Config and Instance
Config page.
5 Configure MSTP parameters
for instance ports
Optional. Configure different instances in the MST region
and configure MSTP parameters for instance ports on
Spanning Tree→MSTP Instance→Instance Port
Config page.
7.4 STP Security
Configuring protection function for devices can prevent devices from any malicious attack against
STP features. The STP Security function can be implemented on Port Protect and TC Protect
pages.
Port Protect function is to prevent the devices from any malicious attack against STP features.
7.4.1 Port Protect
On this page you can configure loop protect feature, root protect feature, TC protect feature,
BPDU protect feature and BPDU filter feature for ports. You are suggested to enable
corresponding protection feature for the qualified ports.
¾ Loop Protect
In a stable network, a switch maintains the states of ports by receiving and processing BPDU
packets from the upstream switch. However, when link congestions or link failures occurred to the
network, a down stream switch does not receive BPDU packets for certain period, which results in
spanning trees being regenerated and roles of ports being reselected, and causes the blocked
ports to transit to forwarding state. Therefore, loops may be incurred in the network.
The loop protect function can suppresses loops. With this function enabled, a port, regardless of
the role it plays in instances, is always set to blocking state, when the port does not receive BPDU
packets from the upstream switch and spanning trees are regenerated, and thereby loops can be
prevented.
¾ Root Protect
A CIST and its secondary root bridges are usually located in the high-bandwidth core region.
Wrong configuration or malicious attacks may result in configuration BPDU packets with higher
priorities being received by the legal root bridge, which causes the current legal root bridge to lose
its position and network topology jitter to occur. In this case, flows that should travel along
high-speed links may lead to low-speed links, and network congestion may occur.
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