Preventing Loops On Port Extender Ports - Dell C9000 Series Networking Configuration Manual

Preventing Loops on Port Extender
Ports
You can specify the threshold value and a time interval for the maximum number of station moves to prevent
loops on a port extender (PE) port . When the number of station moves for a specified MAC address exceeds
the configured threshold value in the configured time, a loop is detected on the PE ports. You can configure
the mac-address-table station-move threshold number interval seconds command to bring
down the line protocol on all active ports in the learned path, except for the port with the lowest interface
index (ifIndex) to prevent a possible loop.
To specify the threshold value and timer interval for the maximum number of station move
1 Enter Configuration mode.
CONFIGURATION mode
Dell(conf)# mac-address-table station-move threshold number interval seconds
• number is the threshold value. The range is from 5 to 50.
After you enter a threshold value, you can specify a time interval in seconds. The range is from 1 to 60
seconds.
Dell(conf)# mac-address-table station-move threshold 5 interval 30
NOTE: Dell Networking OS recommends that you use the command because xSTP protocols are
not supported on PEs.
2 If a station move for a MAC address is detected above the configured threshold and within the specified
time, a syslog message is triggered with the port information. All ports on which the station move was
detected are shut down, except for the port with the lowest interface index. Only the port with the
lowest ifIndex remains active. For example:
Jun 18 09:55:35: %RPM0-P:RP %MACMGR-1-PE LOOP DETECTION: Loop occurred on PE
interfaces:oldInterface: peGigE 0/2/47, newInterface: peGigE 0/1/20,vlanId:
3902, macAddr: 00:aa:00:00:00:
3 When a PE interface is shut down due to a PE loop violation, you must manually reset it. To reset the
interface, shut it down by entering the shutdown command and then re-enable it by entering the no
shutdown command.
4 To display the PE ports that are shut down due to loop detection, enter the show mac learning-
limit violate-action command.
Dell# show mac learning-limit violate-action
Interface Violation-Type Violate-Action Status
PeGi 0/2/47 Pe-Loop Shutdown PEloop-disable
PeGi 100/0/20 Pe-Loop Shutdown PEloop-disable
PeGi 255/0/47 Pe-Loop Shutdown PEloop-disable
Po 1 Pe-Loop Shutdown PEloop-disable
Po 100 Pe-Loop Shutdown PEloop-disable
5 To display the reason why the line protocol is down on a PE port or port channel, enter the show
interface command.
Port Extenders (PEs) 828