  This report describes our submission to the track 1 and track 2 of the
VoxCeleb Speaker Recognition Challenge 2021 (VoxSRC 2021). Both track 1 and
track 2 share the same speaker verification system, which only uses
VoxCeleb2-dev as our training set. This report explores several parts,
including data augmentation, network structures, domain-based large margin
fine-tuning, and back-end refinement. Our system is a fusion of 9 models and
achieves first place in these two tracks of VoxSRC 2021. The minDCF of our
submission is 0.1034, and the corresponding EER is 1.8460%.
