pNIC

A physical network interface card (pNIC) is a hardware component that provides a computer system with a network connection. Typically installed in a PCIe slot or built into a motherboard, a pNIC connects to a local area network through an Ethernet switch and uses a unique Media Access Control (MAC) address. pNICs support a range of Ethernet speeds, such as 1 Gbps, 10 Gbps, 25/40/100 Gbps, depending on the model. Modern devices may include hardware offload features to improve performance, such as TCP/IP offload, checksum offload, large receive offload, segmentation offload, and support for VLAN tagging and jumbo frames.

In data centers and enterprise networks, pNICs can be configured for redundancy and throughput through link aggregation or NIC teaming, often using industry standards like LACP. They may also support virtualization features such as Single Root I/O Virtualization (SR-IOV), which partitions a single physical function into multiple virtual functions that can be assigned to virtual machines, while the physical function handles management and arbitration.

Virtualization environments distinguish between pNICs and virtual NICs (vNICs). The pNIC provides the physical path to the network, while hypervisors and virtual switches present vNICs to guest VMs. Traffic from multiple VMs can traverse a single pNIC, with performance and isolation managed by the virtualization infrastructure and NIC capabilities.

Management and deployment: pNICs require appropriate drivers and firmware, updated through the host operating system or hypervisor. Common vendors include Intel, Broadcom, Mellanox/NVIDIA, and Realtek, chosen for performance, driver maturity, and interoperability with network gear.