Users Guide

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 congured threshold and within the specied time, a syslog message is
triggered with the port information. All ports on which the station move was detected are shut down, except the old interface. 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 detection, 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.
EXEC mode
Dell(conf-if-po-1)#do show interface port-channel 1
Port-channel 1 is up, line protocol is down(Pe Loop Detection)
This section covers the enhancements to this feature based on scenarios in Dell Networking OS 9.11.2.0:
Loop caused due to mis-cabling across PEs or within a PE
• Two PE interfaces PEX1 and PEX2 are looped back wrongly due to mis-cabling.
• Both the interfaces are assigned to a VLAN which is assigned an IP address.
A simple ping for an IP address in the subnet will result in a continuous loop without being detected. The reason being we don’t learn our
own MAC address and hence, the MAC station move is never detected. Without station moves, the existing PE Loop Detection Feature
would not kick-in. If there is no data trac on the LAN to detect the loop, the control PDUs like LACP, LLDP, ARP, DHCP etc., will be used
to detect loops at PE.
• At kernel, the following validations are done:
• Any control PDU (LACP or LLDP or ARP or DHCP etc) received at CB will be rst checked for the source MAC address against
matching any one of its PEX interface address.
• In this scenario the source MAC could be the system MAC and in this case, the receiving PE interface would be brought down to
cut the loop.
Port Extenders (PEs)
733