VR2-0311

① SA Source

Context Before

Source: Nvidia VR NVL72 Component BoM and Power Budget Model

For the GB200/GB300, the PCIe signal distance between the GPU/CPU and the CX-7/8 is shorter than the Ethernet/InfiniBand signal distance between the CX-7/8 and the OSFP cages. Previously – having to transmit a 200G Ethernet/InfiniBand signal from the NIC in the back half of the compute tray to the OSFP cage in the front of the compute tray necessitated the use of flyover cables as the signal loss over PCB at 200Gbit/s (uni-directional) per lane is too high.

Evidence

But now that the NIC is closer to the OSFP cage, the lower speed PCIe Gen6 signal (64Gbit/s per lane uni-directional) travels the longer distance

Context After

PCB vs Flyover Cables

Nevertheless, it is still challenging to drive a PCIe Gen6 signal over around 500mm of PCB distance from the Strata Module to the front of the Orchid Module. In addition to having high quality SerDes, proper signal integrity is still achievable by upgrading PCB materials.

② Atomic Claim

現在 NIC 更靠近 OSFP cage,因此速率較低的 PCIe Gen6 signal(每 lane 64Gbit/s 單向)改為走較長距離。

  • Epistemic Mode: ASSERTED
  • Mapping Status: COMPLETE

③ Semantic Frame

{
  "comparison_expression": "現在 NIC 更靠近 OSFP cage,因此速率較低的 PCIe Gen6 signal(每 lane 64Gbit/s 單向)改為走較長距離。",
  "entities": [
    {
      "id": "04_knowledge_base/NIC",
      "label": "NIC"
    },
    {
      "id": "04_knowledge_base/OSFP (Octal Small Form-factor Pluggable)",
      "label": "OSFP"
    },
    {
      "id": "04_knowledge_base/PCIe",
      "label": "PCIe Gen6"
    }
  ],
  "frame_type": "COMPARISON",
  "metric": "SPEED",
  "operator": "LESS_THAN",
  "qualifiers": {
    "condition_text": null,
    "numeric_mentions": [
      "64Gb"
    ],
    "temporal_mentions": [
      "現在"
    ]
  }
}

④ Canonical Entity Mapping

RoleSurface LabelCanonical Target
comparison_entity_0NICNIC
comparison_entity_1OSFP04_knowledge_base/OSFP (Octal Small Form-factor Pluggable)
comparison_entity_2PCIe Gen6PCIe

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。