clm_8d8d2f4ed08b4dd2b178aa8b611043f9_r1

NIEK2-0253

① SA Source

• Source: 開啟完整 SA 文章
• Section: Rubin Ultra NVL288
• Line hint: 311

Context Before

Though not officially discussed by Nvidia at GTC 2026, an NVL288 concept has been explored within the supply chain. This would entail two NVL144 Kyber racks placed adjacent to each other, with a rack-to-rack copper backplane used to connect the two racks. One possibility is that all 288 GPUs are connected all to all, but this would require higher radix switches than the current NVLink 7 switches which only offer a maximum radix of 144 ports of 200G.

If Rubin Ultra NVL288 is deployed, each Rubin Ultra GPU will have a scale-up bandwidth of 14.4Tbit/s uni-di, requiring 144 DPs of cables to connect the NVLink 7 switches. 72 DPs per GPU times 288 GPUs means a total of 20,736 additional DPs required to connect this larger world size domain. This entails a lot of cables, so it is an upper bound of how much cable content could be used.

Evidence

The radix of the 28.8T NVLink Switch limits the number of GPUs that each switch can connect while still providing for cross-rack connectivity

Context After

Source: SemiAnalysis

② Atomic Claim

28.8T NVLink Switch 的 radix 會限制每顆 switch 可連接的 GPUs 數量，同時還必須保留 cross-rack connectivity。

• Epistemic Mode: ASSERTED
• Mapping Status: COMPLETE

③ Semantic Frame

{
  "additional_nodes": [],
  "frame_type": "RELATION",
  "object": {
    "id": "04_knowledge_base/GPU",
    "label": "GPUs"
  },
  "predicate": "CONNECTS_TO",
  "qualifiers": {
    "condition_text": null,
    "numeric_mentions": [
      "28.8"
    ],
    "temporal_mentions": []
  },
  "subject": {
    "id": "04_knowledge_base/NVLink",
    "label": "NVLink"
  }
}

④ Canonical Entity Mapping

Role	Surface Label	Canonical Target
subject	NVLink	NVLink
object	GPUs	GPU

⑤ Human Review

請在 Properties 逐項確認：

• 原文 → Atomic Claim 是否忠實
• Atomic Claim → Semantic Frame 是否忠實
• Canonical Entity mapping 是否正確
• Epistemic mode 是否保留原文語氣
• 最後選擇 review_action

Review state

Markdown 內文不是正式 approval。只有 Apply bridge 寫入的 Decision Ledger event 才是正式決策。