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FAQ-Broadcasting packets with ethertype 0x999a

Publication Date:  2019-01-14 Views:  259 Downloads:  0

Issue Description

Customer noticed that on NE05’s are regularly broadcasting packets that are completely unknown  with ethertype 0x999a, which is an unregistered ethertype.

What is this, and how can be disable it?


Customer receive those packets because you have configured loopback-detect command  on  device.


loop-detect trigger enable


After the loopback-detect command is run, the device sends special detection packets whose Ethernet type is 0x999a. In the packets, the destination MAC address is the broadcast address and the source MAC address is the device's MAC address. If a port receives detection packets from itself, there may be a loopback fault and the port blocks itself while reporting an alarm. If the port does not receive the detection packets after the delay time elapses, the loopback fault has been rectified and the port automatically cancels the block.