A plurality of data packets encoded according to a first protocol are received which encapsulate data encoded according to a second protocol. A first source address is extracted from the packets according to the first protocol, it is determined whether or not the first source address is a substantial duplicate of a known assigned address. If it is a duplicate, a second source address is extracted from the encapsulated data according to the second protocol, and the first source address and said second source address are provided in an enhanced error log so that a system administrator may correct the duplicate assigned address. Enhanced embodiments of the invention included analysis of data encapsulated by a third, fourth and subsequent protocols, and automatic determination of each protocol encoding format.