Specifications

CLI Management Guide
TigerAccess™ EE
300 SMC7824M/VSW
8.5 Loop Detection
The loop may occur when double paths are used for the link redundancy between
switches and one sends unknown unicast or multicast packet that causes endless packet
floating on the LAN like loop topology. That superfluous traffic eventually can result in
network fault. It causes superfluous data transmission and network fault.
To prevent this, the switch provides the loop detecting function. The loop detecting
mechanism is as follows:
The switch periodically sends the loop-detecting packet to all the ports with a certain in-
terval, and then if receiving the loop-detecting packet sent before, the switch performs a
pre-defined behavior.
To enable/disable the loop detection globally, use the following command.
Command Mode Description
loop-detect {enable | disable} Bridge Enables/disables the loop detection globally.
For the detailed configuration of the loop detection, you need to issuing the loop-detect
enable command first. If you do not, all the commands concerning the loop detection will
show an error message.
To enable/disable the loop detection on a specified port, use the following command.
Command Mode Description
loop-detect PORTS Enables the loop detection on a specified port.
no loop-detect PORTS
Bridge
Disables the loop detection on a specified port.
To define the behavior on a specified port when a loop is occurred, use the following
command.
Command Mode Description
loop-detect PORT block
Enables the blocking option. This configures a speci-
fied port to automatically change its state to BLOCKED
when a loop is detected on it. (default: disable)
loop-detect PORT unblock
Forces the state of a blocked port to change to NOR-
MAL.
loop-detect PORT timer <0-
86400>
Sets the interval of changing the state of a blocked port
to NORMAL. If you set the interval as 0, the state of the
blocked port will not be changed automatically.
(default: 600 seconds)
no loop-detect PORT block
Bridge
Disables the blocking option.
To set the interval of sending the loop-detecting packet, use the following command.
Command Mode Description
loop-detect PORTS period <1-
60>
Bridge
Sets the interval of sending the loop-detecting packet.
(default: 30 seconds)
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