3Com 400 Family, Configuration Manual

Page: 181 / 344

RSTP Configuration 179
again. In this case, the former root port will turn into a BPDU specified port and
the former blocked ports will enter into a forwarding state, as a result, a link loop
will be generated.
The security functions can control the generation of loops. After it is enabled, the
root port cannot be changed, the blocked port will remain in “Discarding” state
and will not forward packets, thus avoiding link loops.
You can use the following command to configure the security functions of the
Switch.
Perform the following configuration in corresponding views.
Table 187 Configure the Switch Security Function
After being configured with BPDU protection, the Switch will disable the edge
port through RSTP, which receives a BPDU, and notify the network manager at the
same time. Only the network manager can resume these ports.
The port configured with Root protection only plays a role of a designated port.
Whenever such a port receives a higher-priority BPDU when it is about to turn into
a non-designated port, it will be set to a listening state and not forward packets
any more (as if the link to the port is disconnected). If the port has not received
any higher-priority BPDU for a certain period of time thereafter, it will resume to
the normal state.
When you configure a port, only one configuration at a time can be effective
among loop protection, root protection, and edge port configuration.
By default, the Switch does not enable loop protection, BPDU protection or Root
protection.
For detailed information about the configuration commands, refer to the
Command Reference Guide .
Display and Debug RSTP After the above configuration, execute
display
command in all views to display
the running of the RSTP configuration, and to verify the effect of the
configuration. Execute
reset
command in User View to clear the statistics of RSTP
module. Execute
debugging
command in User View to debug the RSTP module.
Operation Command
Configure Switch BPDU protection (from System View)
stp bpdu-protection
Restore the disabled BPDU protection state, as defaulted,
(from System View).
undo stp bpdu-protection
Configure Switch Root protection (from Ethernet Port
View)
stp root-protection
Restore the disabled Root protection state, as defaulted,
(from Ethernet Port View)
undo stp root-protection
Configure Switch loop protection function (from Ethernet
Port View)
stp loop-protection
Restore the disabled loop protection state, as defaulted
(from Ethernet Port View)
undo stp loop-protection