Ruijie RG-S2900G-E Series, Configuration Manual

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Configuration Guide MSTP Configuration
Understanding TC Guard
The TC-Protection function can reduce the removal of MAC address entries and
ARP entries when a lot number of TC messages are generated in a network.
However, you need to do more delete oeprations in case of TC message attack.
Furthermore, the TC message is propagated and will have an effect on the
whole network. The TC Guard function allows you to disable the propagation of
the TC message globally or on ports. When TC Guard function is configured
globally or on a port, the port will shield the TC messages received or produced
to prevent from propagating them to other ports. In this way, this funciton can
manage TC message attack in the network and maintain the network stability.
Moreover, this function can prevent from interrupting core routes due to the
oscillation of the devices on the access layer.
Caution
Network communication will be broken off if you use tc-guard
function incorrectly.
You are recommended to enable this function when you ensure
that there is illegal tc message attack in the network.
If you enable global tc-guard, then all the ports will not spread tc
message. It is applicable for those devices that are accessed on
the desk to enable this function.
If you enable interface tc-guard, then the topology change and tc
message received on this port will not be spreaded to other ports.
It is applicable for up-link ports especially aggregated ports to
enable this function.
Understanding TC Filter
After configured with TC Guard, a port will not spread TC messages to other
ports participating in STP algorithm. Here the TC messages refer to the
messages the port receives or generates by itself. The port generates a TC
message when the forwarding state of the port changes, for example, from
block to forwarding, which means the topology may change.
In this case, some problems may be induced. Because TC Guard stops TC
messages from spreading, the device does not clear the MAC address of the
related port, it will forward data to the wrong port when topology changes.