Dell C1048P Port Extender Networking Configuration Guide for the C9000 Series - Page 828

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 learninglimit 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