company · explainer · draft
OpenAI (training fabric fragment)
OpenAI has published resilient AI training-cluster networking (MRC multipath RDMA + static SRv6 source routing) and capacity partnership notes (e.g. Stargate / OCI). ChatGPT/API public edge (CDN, anycast, PoPs, ASN) is not publicly documented in the curated primaries — keep it in Known unknowns.
In one sentence. Teaching the published MRC/SRv6 training-fabric fragment without inventing an inference-edge anycast map or freezing paper figures as live cluster inventories.
Why it exists
Large GPU training fabrics need high throughput under failures. MRC spreads a transfer across many paths and stops using failed paths quickly; static SRv6 embeds path (uSID) so switches need not run adaptive routing that fights MRC (OpenAI MRC post + PDF). Cross-link: `/architectures/spine-leaf-clos/` for Clos teaching contrast — MRC paper compares multi-plane themes, not an OpenAI site map.
Visual walkthrough
A large training transfer spreads across many fabric paths (MRC multipath RDMA). Single-path RDMA collapses when a link fails; MRC is published as resilience for AI training fabrics.
Control vs data plane
Control plane
Static SRv6 source routing with dynamic routing disabled in switches (as published). This is cluster fabric control, not Internet BGP anycast. Stargate posts name compute partnerships without disclosing edge/CDN control planes.
Data plane
Multipath RDMA (MRC) across high-speed training fabrics; NICs/switches called out in the paper are product examples in that publication window — era-label them. Inference/API packet paths are unpublished.
Request / packet path
North–south
Training north–south is partner datacenter networking (Microsoft, OCI, etc.) named in capacity posts — fabric internals beyond MRC remain private. Public ChatGPT/API edge path is a known unknown.
East–west
East–west inside the training cluster follows MRC/SRv6 multipath themes. Non-training WAN between sites is unpublished.
Scaling & math
Do not invent cluster sizes, oversubscription ratios, or site lists beyond illustrative paper figures / marketing capacity posts. Reject third-party “OpenAI vs Anthropic network” rumor articles as non-primary.
When it breaks
- Training transfer throughput collapses when paths fail.
Cause. Without multipath resilience, single-path RDMA suffers from failed links.
Mitigation. MRC stops using failed paths quickly and sprays across many paths as published.
- Adaptive switch routing fights multipath spraying.
Cause. Dynamic routing in switches conflicts with MRC path selection.
Mitigation. Paper/post: static SRv6 source routing embeds path; disable adaptive routing that fights MRC.
- Cannot debug ChatGPT/API edge with primary topology docs.
Cause. Public edge/CDN/anycast/ASN architecture not published in curated sources.
Mitigation. Keep edge in Known unknowns; do not invent Cloudflare-like diagrams.
Misconceptions
- “MRC/SRv6 posts disclose ChatGPT’s public CDN/anycast edge.” — They document training-cluster networking.
- “Partnership capacity posts are a full site inventory.” — They name partners/regions at marketing depth; fabric beyond MRC stays private.
Reference expression
Primary: MRC networking post; MRC/SRv6 PDF; Stargate compute infrastructure post. Optional adjacent: Habitat storage / PostgreSQL scaling posts are product storage narratives, not edge topology. review: draft.
Standards & sources
- openai-mrc-networking · MRC supercomputer networking postPrimary source, retrieved 2026-09-20. Supercomputer networking to accelerate large scale AI trainingSupercomputer networking to accelerate large scale AI training — MRC supercomputer networking post
- openai-mrc-srv6 · MRC + SRv6 PDF companionPrimary source, retrieved 2026-09-20. Resilient AI Supercomputer Networking using MRC and SRv6Resilient AI Supercomputer Networking using MRC and SRv6 — MRC + SRv6 PDF companion
- openai-stargate-compute · Compute infrastructure / capacity partnershipsPrimary source, retrieved 2026-09-20. Building the compute infrastructure for the Intelligence AgeBuilding the compute infrastructure for the Intelligence Age — Compute infrastructure / capacity partnerships
Known unknowns
- ChatGPT / API public edge architecture (CDN, anycast, PoPs, ASN) — not publicly documented.
- Non-training WAN between sites, peering policy, and DDoS posture.
- Exact cluster sizes, oversubscription ratios, and site lists beyond illustrative paper figures / marketing capacity posts.
- Partner datacenter fabric internals beyond the MRC publication.
Check yourself
MRC as published primarily addresses…
- Internet anycast PoP maps for ChatGPT
- Multipath RDMA resilience in AI training fabrics
- Airbnb SmartStack discovery
- Starlink Ka gateway licensing
Answer: Multipath RDMA resilience in AI training fabrics. OpenAI MRC post/PDF: training-cluster multipath RDMA.
Static SRv6 in the MRC design is used to…
- Replace all GPU NICs with Wi-Fi
- Embed path (uSID) so switches need not run adaptive routing that fights MRC
- Announce AS13335
- Configure Front Door VIP rings
Answer: Embed path (uSID) so switches need not run adaptive routing that fights MRC. MRC/SRv6 PDF: static source routing; dynamic routing disabled.
OpenAI public edge (CDN/anycast/ASN) for ChatGPT/API is…
- Fully documented like Unimog
- A known unknown in curated primaries
- Identical to Netflix Open Connect AS2906
- Proven by PeeringDB alone as primary
Answer: A known unknown in curated primaries. Phase 7 ship rule: edge = unknowns.
Stargate compute posts should be read as…
- Full packet-level fabric dumps
- Capacity / partnership narratives — not edge topology disclosures
- FCC Gen2 satellite authorizations
- Service Fabric 2018 live maps
Answer: Capacity / partnership narratives — not edge topology disclosures. Capacity partnerships ≠ published edge architecture.