The finer points of autonegotiation have been discussed; however, some drawbacks need to be discussed. Numerous network problems resulted when the autonegotiation feature was first deployed. The issues ranged from degradation in performance to connectivity loss. The cause of some of these problems included advanced software features that came with the NIC, vendors not fully conforming to 802.3u standard, and buggy code. These days, now that manufacturers have resolved these issues, misconfiguration is the biggest remaining problem. Table 1-5 and Table 1-6 show various consequences from misconfigurations. For instance, a duplex mismatch can degrade performance on the wire and potentially cause packet loss.