The bucket drops counter would always be increased on the lowest LAG child interface though not passing traffic on that interface.

Even if lowest LAG child interface is down state, counters will be increased.

This KB describes this behavior.

The bucket drops counter would be increased on the lowest LAG child interface though not passing traffic.

This behavior can be seen by making a congestion traffic for policer function.

Here is the test topology and output.

IXIA------->(xe-0/0/3)QFX5100(ge-0/0/0-2)------ae10------>Peer device.

When IXIA generates congestion traffic, bucket drops will always be increased on ge-0/0/0 which is disabled and no increment on ge-0/0/1 and ge-0/0/2.

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root@QFX5100> show interfaces ge-0/0/0 extensive | match bucket

  Errors: 0, Drops: 0, Framing errors: 0, Runts: 0, Bucket drops: 0, Policed discards: 0, L3 incompletes: 0, L2 channel errors: 0, L2 mismatch timeouts: 0, FIFO errors: 0, Resource errors: 0

  Carrier transitions: 0, Errors: 0, Drops: 0, Collisions: 0, Aged packets: 0, FIFO errors: 0, HS link CRC errors: 0, MTU errors: 0, Resource errors: 0, Bucket drops: 25702971330


{master:0}

root@QFX5100> show interfaces ge-0/0/0 extensive | match bucket

  Errors: 0, Drops: 0, Framing errors: 0, Runts: 0, Bucket drops: 0, Policed discards: 0, L3 incompletes: 0, L2 channel errors: 0, L2 mismatch timeouts: 0, FIFO errors: 0, Resource errors: 0

  Carrier transitions: 0, Errors: 0, Drops: 0, Collisions: 0, Aged packets: 0, FIFO errors: 0, HS link CRC errors: 0, MTU errors: 0, Resource errors: 0, Bucket drops: 25703179258

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{master:0}

root@QFX5100> show interfaces ge-0/0/1 extensive | match bucket

  Errors: 0, Drops: 0, Framing errors: 0, Runts: 0, Bucket drops: 0, Policed discards: 0, L3 incompletes: 0, L2 channel errors: 0, L2 mismatch timeouts: 0, FIFO errors: 0, Resource errors: 0

  Carrier transitions: 3, Errors: 0, Drops: 869, Collisions: 0, Aged packets: 0, FIFO errors: 0, HS link CRC errors: 0, MTU errors: 0, Resource errors: 0, Bucket drops: 0


{master:0}

root@QFX5100> show interfaces ge-0/0/2 extensive | match bucket

  Errors: 0, Drops: 0, Framing errors: 0, Runts: 0, Bucket drops: 0, Policed discards: 0, L3 incompletes: 0, L2 channel errors: 0, L2 mismatch timeouts: 0, FIFO errors: 0, Resource errors: 0

  Carrier transitions: 3, Errors: 0, Drops: 0, Collisions: 0, Aged packets: 0, FIFO errors: 0, HS link CRC errors: 0, MTU errors: 0, Resource errors: 0, Bucket drops: 0

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The policer attached to LAG interface is common across all member interfaces and hence always first member of the AE will be fetched for filter counter.

It is working as expected and limitation.