Add vLLM Semantic Router Blog

[youkaichao]

move #76 here to enable previews

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[rootfs]

@youkaichao thank you for reviewing, is it ready to go for publishing today? Thank you!

[windsonsea]

Removing AI-generated tags and style can make the content more inviting for human to read.

[Xunzhuo]

Preview is here: https://c8e293a4.vllm-blog-source.pages.dev/2025/09/01/semantic-router

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Project	Deployment	Preview	Comments	Updated (UTC)
vllm-project-github-io	Ready	Preview	Comment	Sep 10, 2025 3:57am

[simon-mo]

I reviewed the blog. Two comments

• I would suggest tuning down the "business value" of semantic router. I believe (1) it is a speculation (2) it distract the technical value of this post
• Can you run the ModernBERT with vLLM? If so, we should put that down as future work, if not, we should clearly explain why

[Xunzhuo]

cool, thanks for the review @simon-mo, yep, for the first one, I think we need to emphasize the technique part.

And for the second one, I think you raised a key point which is in our roadmap: pluggable embedding model architecture, so for the modernBERT, that is something lightweight and embedded inside the router, and for other embedding model which can be deployed by vLLM engine and that can be also integrated with vsr with external call.

[rootfs]

Thank you @simon-mo for the review!

Can you run the ModernBERT with vLLM? If so, we should put that down as future work, if not, we should clearly explain why

At the moment, the semantic router uses the modernBERT for internal classification. However, we will explore more ways to get text embedding for semantic cache. Many of these models can be hosted by vLLM and I believe this will be more extensible.

We'll detail these directions and use cases in the upcoming revision!