Stp Interface Loop-Protection; Stp Interface Mcheck - 3Com 8807 Command Reference Manual

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stp interface mcheck

interface-number ] }&<1-10>. For detail descriptions of interface-type and
interface-number parameters, refer to the corresponding descriptions in Port
Command Manual. &<1-10> means that the preceding parameters can be
entered up to 10 times
Description
Use the stp interface loop-protection command to enable loop protection on
the switch in system view.
Use the undo stp interface loop-protection command to restore the default
loop protection state.
When port roles change, you can use the stp interface loop-protection
command to change port state from forwarding state to discarding state, thus
avoiding port loopback.
Use the undo stp interface loop-protection command to restore the default
running state of loop protection in system view.
The root port and other blocked ports maintain their state according to the BPDUs
sent by uplink switch. Due to link congestion or unidirectional link failure, these
ports may be unable to receive BPDUs and the switch will select root port again. In
this case, the former root port will turn into the specified port and the former
blocked ports will change to the forwarding state, and link loop appears.
The loop protection function can inhibit the generation of loop. After it is enabled,
the root port role will change according to the uplink port state. The blocked port
will maintain in discarding state and do not forward packets, thus avoiding link
loop.
By default, loop protection is disabled.
CAUTION: If the equipment connected to the port of the switch cannot send STP
packets to the switch, do not configure the loop-protection command;
otherwise the port will be congested for a long time.
Related command: stp loop-protection.
For a loopback port, if the port participates in STP calculation, it must be specified
port regardless of internal loop or external loop. However, the port is always set to
be in discarding state on all instances.
Example
# Enable loop protection on the Ethernet2/1/1.
<SW8800>system-view
System View: return to User View with Ctrl+Z.
[SW8800] stp interface Ethernet2/1/1 loop-protection
Syntax
stp interface interface-list mcheck
View
System view
MSTP Configuration Commands 189