EMC 105-000-855-00 MELLANOX CX312C 2x10Gb Dual Port Ethernet CNA Card

The EMC 105-000-855-00 is an OEM-branded Mellanox ConnectX-3 Dual-Port 10 Gigabit Ethernet Converged Network Adapter (CNA), specifically the CX312C model (full Mellanox part typically MCX312A-XCBT or equivalent variant). This is a high-performance, dual-port 10GbE network interface card widely used in EMC/Isilon storage nodes, Dell EMC servers, and other enterprise environments during the 2010s–early 2020s.

The CX312C is a PCIe 3.0 x8 card featuring two 10 Gigabit Ethernet SFP+ ports that support converged networking protocols. It is designed for high-bandwidth, low-latency applications such as cluster interconnects, iSCSI storage networking, NFS/SMB file serving, virtualization fabrics, and data center server-to-switch links.

In EMC/Isilon deployments, this card was one of the most commonly installed NICs in Isilon H-series (hybrid) and F-series (all-flash) nodes, providing fast node-to-node communication across scale-out NAS clusters. It supports RoCE (RDMA over Converged Ethernet) for ultra-low-latency data transfers and FCoE (Fibre Channel over Ethernet) for converged storage networking.

The card includes extensive hardware offloads:

• TCP/UDP/IP stateless offloads
• Large Send Offload (LSO)
• Receive Side Scaling (RSS)
• iSCSI/SMB Direct acceleration
• FCoE support
• SR-IOV (up to 127 virtual functions)
• RDMA/RoCE acceleration (low CPU overhead)

This makes it a true CNA (Converged Network Adapter) — capable of handling Ethernet, storage (iSCSI/FCoE), and low-latency RDMA traffic on the same ports.