Symptoms

In certain topologies where the upstream switch floods a unicast l2 destination to all ports on a link aggregation group (LAG), the VELOS blade may emit that packet back out the same link into which it ingressed causing an intermittent packet storm between the VELOS LAG and upstream switch.

Impact

A packet storm may occur.

Conditions

A link aggregation group (LAG) spanning more than one interface and an upstream switch that floods a unicast packet for the same layer 2 destination across all ports of that LAG.

Workaround

Remove the trunk topology, or use a trunk residing on a single interface.

Fix Information

Packets are no longer forwarded out of a link aggregation group (LAG) interface, if the LAG interface is the source of the incoming packets. This ensures that there are no loops in the network, if an upstream switch floods unicast packets to a VELOS LAG.

Behavior Change