AI training clusters and large-language-model inference workloads have pushed data centre networking into 800G as the new default. Arista 7060X6, Cisco Nexus 9332D-H2R, and Juniper QFX5240 are the three platforms most UK AI / hyperscale-tier enterprise buyers shortlist. All three are 32×800G capable. The differentiators are buffering architecture, congestion control, telemetry depth, and which switch OS your team operates.
View the data behind this chart
| Arista | Cisco | Juniper | |
|---|---|---|---|
| 800G port density | 7800R3 / 7060X6 | Nexus 9800 / 9500 | PTX10008 |
| EVPN-VXLAN | Best | Strong | Strong |
| RoCEv2 + PFC | Best-in-class | Strong | Strong |
| Mgmt + telemetry | CloudVision | NDFC / Catalyst | Apstra / Mist AI |
| Best for | AI-first | Cisco DC + AI | Apstra IBN |
Why 800G now
NVIDIA H100, DGX B200 and GB200 NVL72 deployments saturate 400G links during distributed training all-reduce phases. 800G doubles per-port capacity and halves the number of fabric links needed for equivalent throughput.
For AI training in particular, network utilisation can hit 80%+ sustained for hours during training runs. Sub-optimal buffering or congestion control adds days to training timelines — and at GPU rental costs, that's £100k+ per delay.
Arista 7060X6 — when to pick it
Arista 7060X6 uses Broadcom Tomahawk 5 (TH5) silicon — 51.2 Tbps, 32×800G or 64×400G. Industry-standard non-blocking architecture.
EOS — Extensible Operating System. Linux-based, fully programmable, mature CloudVision management. The configuration paradigm that hyperscalers (Meta, Microsoft Azure) standardised on.
Best-in-class telemetry. EOS streaming telemetry (gNMI / gRPC) feeds Arista CloudVision for real-time fabric visibility — essential for diagnosing training-job network hot-spots.
Cisco Nexus 9332D-H2R — when to pick it
Cisco's 800G entry runs on Silicon One G200 or Broadcom Tomahawk 5 (depending on SKU). Tighter integration with Cisco UCS compute, Cisco NDFC fabric automation, and existing Cisco TAC support relationships.
NX-OS — familiar to teams running existing Cisco Nexus estates. Configuration translation from current Nexus 9300 / 9500 deployments is straightforward.
See Cisco UK partner + Nexus catalogue.
Juniper QFX5240 — when to pick it
QFX5240 also uses Broadcom Tomahawk 5. Junos OS provides the same commit / rollback / structured config semantics as Juniper's routing + firewall platforms — operational consistency across MX / SRX / QFX.
Juniper Apstra (fabric intent-based automation) is best-in-class for greenfield AI fabric deployments. Define the intent ("32-node leaf-spine, 1:1 oversubscription, RoCEv2 ready"), Apstra generates the configs.
See Juniper UK partner.
The deciding question — which OS + which fabric model
If your network team operates Cisco Nexus today: Cisco 9332D-H2R is the lowest-friction choice. NX-OS familiarity + Cisco support relationship + UCS integration outweigh any feature delta.
If you're building greenfield + want hyperscaler-grade automation: Arista 7060X6 + CloudVision. The EOS configuration model + streaming telemetry are operationally different.
If you run Juniper MX / SRX elsewhere: QFX5240 + Apstra gives you Junos consistency + the best intent-based automation in the category.
For pure £/800G-port: pricing within ~10% across all three at competitive bids. Not the decision driver.