The growing demand for large-scale GPU clusters to train large language models (LLMs) poses a significant challenge to innovation due to high costs and limited accessibility. While state-of-the-art simulators address this issue, they assume a uniform infrastructure. However, device heterogeneity is unavoidable in cloud environments due to resource sharing, frequent updates in device generations, and the inherent intra-chip interconnect heterogeneity. We propose a heterogeneity-aware simulator for distributed LLM training that takes into account the real-world compute and network heterogeneity. Our simulator allows for custom configurations and models the impact of hardware diversity on training time.