Brocade Communications Systems FastIron Administration Manual page 85

Syslog message due to disabled port in loop detection
The following message is logged when a port is disabled due to loop detection. This message also
appears on the console.
loop-detection: port ?/?/? vlan ?, detect, putting into err-disable state
Shutdown prevention for loop-detection on an interface
Prevents shut down for loop-detect on an interface.
In prior FastIron releases, when a loop detection probe packet was received back on an interface, the
corresponding interface would be shut down either permanently or for a specific duration configured by
the user. The new shut down prevention for loop-detection functionality allows users to disable the
shutdown of a port when the loop detection probe packet is received on an interface. This provides
control over deciding which port is allowed to enter into an error-disabled state and go into a shutdown
state when a loop is detected. This function can also be used as a test tool to detect Layer 2 and Layer
3 loops in network current data packet flow.
Limitations of shutdown prevention for loop-detection
Shutdown prevention for loop-detection does not allow any corrective action to be taken on the loop.
There could be network instability due to the presence of network loops, if adequate corrective
measures are not taken by the network administrator.
To enable shutdown prevention for loop detection, follow these steps.
1. Enter global configuration mode.
2. Specify the interface on which you would like to enable the loop-detection shutdown-disable
command.
3. Enter the loop-detection shutdown-disable command.
Brocade (config)# interface ethe 1/7
Brocade (config-if-e1000-1/7)# loop-detection shutdown-disable
Periodic log message generation for shutdown prevention
Generates periodic log messages for shutdown prevention.
You can raise a periodic syslog that provides information about loops in the network. When a loop is
detected because of a loop detection protocol data unit (PDU), on a loop detection shutdown-disabled
interface, the interface will never be put into an error-disabled state, but it will generate a periodic log
message indicating that the interface is in the shutdown-disabled mode. The periodic syslog is by
default generated at an interval of five minutes. You can change this interval as required.
You can globally specify the interval at which the loop-detection syslog message is generated if the
loop detection shutdown-disable command is configured on the port. This configuration applies to all
the ports that have shutdown prevention for loop detection configured.
During a log interval duration window, a log message will be displayed for the first loop detection PDU
received on the interface. This means that there will be only one log message per port in an interval
window.
To configure the periodic log message generation for shutdown prevention, follow these steps.
1. Enter global configuration mode.
2. Enter the loop-detection syslog-interval <num> command.
The following command will set the syslog-interval to 1 hr.
Brocade (config)# loop-detection-syslog-interval 60
FastIron Ethernet Switch Administration Guide
53-1003625-01
Syslog message due to disabled port in loop detection
85