When a multitude of RFID tags are in the interrogating field, an anti-collision technology must be used. In literatures, the reading performance was mainly investigated on the error-free communication links between reader and tags. In the practical situations, particularly where a number of readers and other wireless devices share the same frequency band, the performance on the erroneous links would be significant interest. In this paper, we evaluated Gen2 Air Protocol paying attention to the anti-collision performance in random error communication link. As a result of simulation, two findings were obtained. Firstly, there is an appropriate number of slots depending on the number of tags. This number hardly changes even if a random error is incurred on the link. Secondly, the singulation speed might be significantly degraded particularly in erroneous links, if the optimal number of slots is not chosen. The findings can be interpreted such that the necessary link quality can be derived if the number of tags and permissible time are known a priori to the implementation. For instance, if 64 tags are required to be read in one second, it is necessary to ensure the link quality to be better than BER=10-4 in random error environment.