This counts instances where a source address, even though present in the address table, failed a broader validation check, such as confirming it is actually authorized to originate from this specific physical port, distinct from lportSmdsCntSaNotFounds which flags addresses missing from the table entirely. An admin treats increments here as a potential security concern, since it can indicate a device presenting a source address that belongs to a different port or subscriber. For example, a customer's device misconfigured with another subscriber's SMDS address, or a spoofing attempt, would show up as validation failures rather than not-found since the address itself exists in the table just not for this port.