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The iWARP NIC That Does RDMA Without Touching Your Switch Configuration

RoCE v2 requires a DCB-capable switch with PFC and ETS enabled — and the network engineering team to configure it correctly, test it, and maintain it across firmware upgrades. iWARP requires none of that. The Chelsio T6225-LL-CR is a dual-port 25GbE adapter that delivers full RDMA over standard TCP/IP Ethernet — same switches, same cables, same VLANs, same everything. Plug it in, assign an IP address, enable iWARP in the driver, and the adapter delivers RDMA throughput at line rate. No switch-side PFC buffer tuning. No dropped RoCE packets because a PFC pause frame was lost. No late-night network engineering escalations because a RoCE fabric is dropping packets under load.

Spécifications techniques

Paramètre	spécification
Jeu de puces	Chelsio Terminator 6 (T6) ASIC
Ports	2x SFP28 (25Porter), also supports 10GbE and 1GbE
Host Interface	PCIe 3.0 x8 (64 Gbps — sufficient for 2x 25GbE bidirectional)
RDMA	iWARP (RFC 5040/5041) — full RDMA over TCP/IP. No DCB/PFC required.
Offloads	Full TCP/IP offload (TOE), iSCSI offload, FCoE offload, NVMe-oF offload, iWARP RDMA
SR-IOV	Jusqu'à 128 virtual functions per port
TLS/SSL Offload	Hardware TLS 1.3 offload at line rate (25 Gbps per port, both ports simultaneously)
IPsec Offload	Full IPsec offload (crypto + encapsulation) at line rate
Stateless Offloads	VXLAN, NVGRE, GENEVE, checksum, TSO, LRO, RSS
Pouvoir	~10W typical (both ports active, 25Porter)
Facteur de forme	Low-profile PCIe, full-height bracket included
Physical	167 X 69 millimètre (standard LP PCIe card)
Prise en charge du système d'exploitation	VMware ESXi 7.0+, 8.0+ (iWARP enabled), Windows Server 2019/2022/2025, RHEL 8.6+/9.x, SLES 15 SP4+, Ubuntu 20.04/22.04/24.04
Compatible Servers	All Dell, xFusion, Lenovo servers with PCIe 3.0 x8+ slot
garantie	3-année (with server)

iWARP vs RoCE v2 — When Simplicity Wins

Factor	iWARP (Chelsio T6)	RoCE v2 (Intel E810, Broadcom, Mellanox)
Transport	TCP/IP — routable, works across subnets, any Ethernet switch	UDP/IP — requires DCB/PFC on switch. Lossless fabric required.
Switch configuration	Aucun. Standard TCP/IP. Works on any managed or unmanaged switch.	PFC, ETS, DCBX must be configured on every switch port. Buffer tuning required.
Deployment complexity	Low. Install driver, enable iWARP, assign IP. Done.	Medium-high. Switch-side config required. Network team involvement mandatory.
Cross-subnet RDMA	Yes — TCP/IP is routable. RDMA works across subnets and routers.	Limited. RoCE is L2. RoCEv2 is L3 but requires PFC hop-by-hop, which does not traverse routers.
TLS offload	Yes — line-rate hardware TLS 1.3 on all Chelsio T6 adapters	Not available on most RoCE adapters
Best for	Cross-subnet RDMA, mixed-traffic environments, orgs without dedicated network engineering for storage	Dedicated storage fabrics, single-subnet, lowest-latency RDMA

When to Choose iWARP Over RoCE

Your network team is not dedicated to storage. If the network team manages switches for the entire data center — not just storage — they will resist configuring PFC on every switch port for RoCE. iWARP avoids that fight entirely.
Your RDMA traffic crosses subnets. iWARP over TCP/IP traverses routers. RoCE over UDP/IP does not. If your storage targets are in a different subnet from your compute nodes, iWARP is the only viable RDMA option.
You need TLS encryption at line rate. Chelsio T6 adapters include hardware TLS 1.3 offload engines that encrypt 25 Gbps per port without consuming host CPU cycles. No other 25GbE adapter on the market offers this at Chelsio’s price point.

Compatible Platforms

PCIe 3.0 x8 slot. Compatible with all Dell PowerEdge, xFusion FusionServer, and Lenovo ThinkSystem servers. Chelsio Unified Wire driver supports all listed operating systems with a single driver package.