{
  "status": "shipping",
  "advantages": [],
  "limitations": [],
  "supersedes": [],
  "supersededBy": [],
  "firstSeen": null,
  "lastSeen": null,
  "updated": "2026-10-24",
  "slug": "roce-v2",
  "term": "RoCEv2",
  "aliases": [
    "RoCE v2",
    "RDMA over Converged Ethernet version 2"
  ],
  "definition": "RoCEv2 carries InfiniBand transport packets over UDP/IP on Ethernet, enabling RDMA communication across IP-routed networks.",
  "note": "Encapsulation: RoCEv1 uses Ethernet framing without IP routing; RoCEv2 adds IP and UDP headers. Routability does not establish compatible endpoints or a latency bound. [roce-modes]\n\nReliability: NVMe/RDMA supports reliable queue-pair modes. UDP encapsulation does not change that binding into an unreliable storage protocol. [rdma]\n\nNetwork policy: Cumulus Linux 5.12 documents ECN-only lossy mode and ECN-plus-PFC lossless mode. This is an implementation example, not a universal configuration rule or evidence that both modes perform equally. [roce-qos]\n\nFailure containment: Azure's 2023 report describes a PFC watchdog that drops packets on a persistently paused queue to stop pause propagation. This deployment-specific policy is not a universal losslessness or recovery guarantee. [azure-rdma]",
  "related": [
    "rdma-storage",
    "nvme-rdma",
    "iwarp"
  ],
  "citations": [
    {
      "id": "roce-modes",
      "title": "NVIDIA MLNX_OFED 23.10-3.2.2.0 LTS: RoCE modes",
      "url": "https://networking-docs.nvidia.com/mlnxofedswum/23103220lts/rdma-over-converged-ethernet-roce",
      "accessed": "2026-10-23"
    },
    {
      "id": "rdma",
      "title": "NVM Express NVMe over RDMA Transport 1.3, section 2",
      "url": "https://nvmexpress.org/wp-content/uploads/NVM-Express-NVMe-over-RDMA-Transport-Specification-Revision-1.3-Ratified-2026.07.31.pdf",
      "accessed": "2026-10-23"
    },
    {
      "id": "roce-qos",
      "title": "NVIDIA Cumulus Linux 5.12: RoCE lossy and lossless modes",
      "url": "https://docs.nvidia.com/networking-ethernet-software/cumulus-linux-512/Layer-1-and-Switch-Ports/Quality-of-Service/RDMA-over-Converged-Ethernet-RoCE/",
      "accessed": "2026-10-23"
    },
    {
      "id": "azure-rdma",
      "title": "Bai et al., Empowering Azure Storage with RDMA, NSDI 2023, section 3.1",
      "url": "https://www.usenix.org/system/files/nsdi23-bai.pdf",
      "accessed": "2026-10-24"
    }
  ],
  "provenance": [
    "Specification and versioned vendor-documentation review; no hardware benchmark, congestion experiment or interoperability test.",
    "Published deployment report used for failure-containment context; no network experiment reproduced."
  ]
}