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Hauptverfasser: Wu, Wanxing, Zhu, He, Li, Yixia, Yang, Lei, Zhao, Jiehui, Wang, Hongru, Yang, Jian, Wang, Benyou, Jing, Bingyi, Chen, Guanhua
Format: Preprint
Veröffentlicht: 2026
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Online-Zugang:https://arxiv.org/abs/2602.11877
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author Wu, Wanxing
Zhu, He
Li, Yixia
Yang, Lei
Zhao, Jiehui
Wang, Hongru
Yang, Jian
Wang, Benyou
Jing, Bingyi
Chen, Guanhua
author_facet Wu, Wanxing
Zhu, He
Li, Yixia
Yang, Lei
Zhao, Jiehui
Wang, Hongru
Yang, Jian
Wang, Benyou
Jing, Bingyi
Chen, Guanhua
contents Large language models (LLMs) have achieved success, but cost and privacy constraints necessitate deploying smaller models locally while offloading complex queries to cloud-based models. Existing router evaluations are unsystematic, overlooking scenario-specific requirements and out-of-distribution robustness. We propose RouterXBench, a principled evaluation framework with three dimensions: router ability, scenario alignment, and cross-domain robustness. Unlike prior work that relies on output probabilities or external embeddings, we utilize internal hidden states that capture model uncertainty before answer generation. We introduce ProbeDirichlet, a lightweight router that aggregates cross-layer hidden states via learnable Dirichlet distributions with probabilistic training. Trained on multi-domain data, it generalizes robustly across in-domain and out-of-distribution scenarios. Our results show ProbeDirichlet achieves 16.68% and 18.86% relative improvements over the best baselines in router ability and high-accuracy scenarios, with consistent performance across model families, model scales, heterogeneous tasks, and agentic workflows.
format Preprint
id arxiv_https___arxiv_org_abs_2602_11877
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Towards Fair and Comprehensive Evaluation of Routers in Collaborative LLM Systems
Wu, Wanxing
Zhu, He
Li, Yixia
Yang, Lei
Zhao, Jiehui
Wang, Hongru
Yang, Jian
Wang, Benyou
Jing, Bingyi
Chen, Guanhua
Computation and Language
Artificial Intelligence
Large language models (LLMs) have achieved success, but cost and privacy constraints necessitate deploying smaller models locally while offloading complex queries to cloud-based models. Existing router evaluations are unsystematic, overlooking scenario-specific requirements and out-of-distribution robustness. We propose RouterXBench, a principled evaluation framework with three dimensions: router ability, scenario alignment, and cross-domain robustness. Unlike prior work that relies on output probabilities or external embeddings, we utilize internal hidden states that capture model uncertainty before answer generation. We introduce ProbeDirichlet, a lightweight router that aggregates cross-layer hidden states via learnable Dirichlet distributions with probabilistic training. Trained on multi-domain data, it generalizes robustly across in-domain and out-of-distribution scenarios. Our results show ProbeDirichlet achieves 16.68% and 18.86% relative improvements over the best baselines in router ability and high-accuracy scenarios, with consistent performance across model families, model scales, heterogeneous tasks, and agentic workflows.
title Towards Fair and Comprehensive Evaluation of Routers in Collaborative LLM Systems
topic Computation and Language
Artificial Intelligence
url https://arxiv.org/abs/2602.11877