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Network Adapters

Data Center Bridging (DCB) Data Center Bridging (DCB) is a suite of Institute of Electrical and Electronics Engineers (IEEE) standards that enable Converged Fabrics in the data center, where storage, data networking, cluster IPC and management traffic all share the same Ethernet network infrastructure.DCB underlies the ability of the Windows Server operating to system to provide a defined Quality of Service (QoS) for such Windows Server features as SMB Direct. DCB provides hardware-based bandwidth allocation to a specific type of traffic and enhances Ethernet transport reliability with the use of priority-based flow control. Hardware-based bandwidth allocation is essential if traffic bypasses the operating system and is offloaded to a converged network adapter, which might support Internet Small Computer System Interface (iSCSI), Remote Direct Memory Access (RDMA) over Converged Ethernet, or Fiber Channel over Ethernet (FCoE). Priority-based flow control is essential if the upper layer protocol, such as Fiber Channel, assumes a lossless underlying transport.
FibreChannel Interface ANSI developed the FC Standard in 1988 as a practical and expandable method of using fiber optic cabling to transfer data among desktop computers, workstations, mainframes, supercomputers, storage devices, and display devices. ANSI later changed the standard to support copper cabling; today, some kinds of FC use two-pair copper wire to connect the outer four pins of a nine-pin type connector.
FibreChannel-over-Ethernet Interface Fibre Channel over Ethernet (FCoE) is a computer network technology that encapsulates Fibre Channel frames over Ethernet networks. This allows Fibre Channel to use Ethernet networks while preserving the Fibre Channel protocol. The specification was part of the International Committee for Information Technology Standards T11 FC-BB-5 standard published in 2009. FCoE maps Fibre Channel directly over Ethernet while being independent of the Ethernet forwarding scheme. The FCoE protocol specification replaces the FC0 and FC1 layers of the Fibre Channel stack with Ethernet. By retaining the native Fibre Channel constructs, FCoE is meant to integrate with existing Fibre Channel networks and management software. FCoE operates directly above Ethernet in the network protocol stack, in contrast to iSCSI which runs on top of TCP and IP. As a consequence, FCoE is not routable at the IP layer, and will not work across routed IP networks. Since classical Ethernet had no priority-based flow control, unlike Fibre Channel, FCoE required enhancements to the Ethernet standard to support a priority-based flow control mechanism (to reduce frame loss from congestion). The IEEE standards body added priorities in the data center bridging Task Group.
Hardware Quality of Service Hardware Quality of Service ( HW QoS) is a new feature of Windows Server 2022. It is designed to address the issues of previous implementation, specifically; Software implementation had substantial processor overhead, and was limited by the granularity of software timers in scheduling. Software cannot account for packets not delivered through the software path, examples being SR-IOV where packets are going directly to/from the VM, and RDMA. To avoid these problems, it is necessary to have the reservation system implemented entirely in HW. For more information, see "Link is TBD after RTM"
Hardware Timestamping Hardware Timestamping API in Windows Server 2022 enables the use of hardware packet timestamps by an application implementing PTP version 2 in the two step mode, as defined by IEEE. The API provides the ability to discover the network adapter's timestamping capabilities, to associate the network adapter's hardware clock to PTP v2 traffic running over UDP, and establish a relation between the network adapter's clock and the system clock. For more information, see "Link is TBD after RTM"
Internet Protocol Security (IPSec) Internet Protocol Security (IPsec) is a protocol suite for securing Internet Protocol (IP) communications by authenticating and encrypting each IP packet of a communication session. IPsec includes protocols for establishing mutual authentication between agents at the beginning of the session and negotiation of cryptographic keys to be used during the session. IPsec can be used in protecting data flows between a pair of hosts (host-to-host), between a pair of security gateways (network-to-network), or between a security gateway and a host (network-to-host). IPsec is an end-to-end security scheme operating in the Internet Layer of the Internet Protocol Suite, while some other Internet security systems in widespread use, such as Secure Sockets Layer (SSL), Transport Layer Security (TLS) and Secure Shell (SSH), operate in the upper layers of the TCP/IP model. Hence, IPsec protects any application traffic across an IP network. Applications do not need to be specifically designed to use IPsec.
iSCSI Interface iSCSI is an acronym for Internet Small Computer System Interface, an Internet Protocol (IP)-based storage networking standard for linking data storage facilities. By carrying SCSI commands over IP networks, iSCSI is used to facilitate data transfers over intranets and to manage storage over long distances. iSCSI can be used to transmit data over local area networks (LANs), wide area networks (WANs), or the Internet and can enable location-independent data storage and retrieval. The protocol allows clients (called initiators) to send SCSI commands (CDBs) to SCSI storage devices (targets) on remote servers. It is a storage area network (SAN) protocol, allowing organizations to consolidate storage into data center storage arrays while providing hosts (such as database and web servers) with the illusion of locally attached disks. Unlike Fibre Channel, which requires special-purpose cabling, iSCSI can be run over long distances using existing network infrastructure. iSCSI was submitted as draft standard in March 2000
Kernel Mode Remote Direct Memory Access (kRDMA) Kernel RDMA uses the Network Direct Kernel Provider Interface (NDKPI), which is an extension to NDIS that allows IHVs to provide kernel-mode Remote Direct Memory Access (RDMA) support in a network adapter. To expose the adapter's RDMA functionality, the IHV must implement the NDKPI interface as defined in the NDKPI Reference. A NIC vendor implements RDMA as a combination of software, firmware, and hardware. The hardware and firmware portion is a network adapter that provides NDK/RDMA functionality. This type of adapter is also called an RDMA-enabled NIC (RNIC). The software portion is an NDK-capable miniport driver, which implements the NDKPI interface. NDK providers must support Network Direct connectivity via both IPv4 and IPv6 addresses assigned to NDK-capable miniport adapters.
Receive Segment Coalescing (RSC) RSC is a stateless offload technology that helps reduce CPU utilization for network processing on the receive side by offloading tasks from the CPU to an RSC-capable network adapter. CPU saturation due to networking-related processing can limit server scalability. This problem in turn reduces the transaction rate, raw throughput, and efficiency. RSC enables an RSC-capable network interface card to do the following: Parse multiple TCP/IP packets and strip the headers from the packets while preserving the payload of each packet, join the combined payloads of the multiple packets into one packet, and send the single packet, which contains the payload of multiple packets, to the network stack for subsequent delivery to applications. The network interface card performs these tasks based on rules that are defined by the network stack subject to the hardware capabilities of the specific network adapter. This ability to receive multiple TCP segments as one large segment significantly reduces the per-packet processing overhead of the network stack. Because of this, RSC significantly improves the receive-side performance of the operating system (by reducing the CPU overhead) under network I/O intensive workloads.
Receive Side Scaling (RSS) Receive side scaling (RSS) is a network driver technology that enables the efficient distribution of network receive processing across multiple physical cores, not hyper-threaded, in multiprocessor systems. To process received data efficiently, a miniport driver's receive interrupt service function schedules a deferred procedure call (DPC). Without RSS, a typical DPC indicates all received data within the DPC call. Therefore, all of the receive processing that is associated with the interrupt runs on the CPU where the receive interrupt occurs. With RSS, the NIC and miniport driver provide the ability to schedule receive DPCs on other processors. Also, the RSS design ensures that the processing that is associated with a given connection stays on an assigned CPU.
Single Root I/O Virtualization (SR-IOV) The single root I/O virtualization (SR-IOV) interface is an extension to the PCI Express (PCIe) specification. SR-IOV allows a device, such as a network adapter, to separate access to its resources among various PCIe hardware functions. These functions consist of the following types;
A PCIe Physical Function (PF). This function is the primary function of the device and advertises the device's SR-IOV capabilities. The PF is associated with the Hyper-V parent partition in a virtualized environment.
One or more PCIe Virtual Functions (VFs). Each VF is associated with the device's PF. A VF shares one or more physical resources of the device, such as a memory and a network port, with the PF and other VFs on the device. Each VF is associated with a Hyper-V child partition in a virtualized environment. Each PF and VF is assigned a unique PCI Express Requester ID (RID) that allows an I/O memory management unit (IOMMU) to differentiate between different traffic streams and apply memory and interrupt translations between the PF and VFs. This allows traffic streams to be delivered directly to the appropriate Hyper-V parent or child partition. As a result, non-privileged data traffic flows from the PF to VF without affecting other VFs. SR-IOV enables network traffic to bypass the software switch layer of the Hyper-V virtualization stack. Because the VF is assigned to a child partition, the network traffic flows directly between the VF and child partition. As a result, the I/O overhead in the software emulation layer is diminished and achieves network performance that is nearly the same performance as in non-virtualized environments.
UDP Segmentation Offload UDP Segmentation Offload (USO) reduces CPU utilization in UDP based protocols such as QUIC. It does this by offloading the segmentation of UDP datagrams that are larger than the MTU of the network. For more information, see
Virtual Machine Queue (VMQ) Virtual machine queue (VMQ) is a feature available to computers with the Hyper-V server role installed, that have VMQ-capable network hardware. VMQ uses hardware packet filtering to deliver packet data from an external virtual machine network directly to virtual machines, which reduces the overhead of routing packets and copying them to the virtual machine. When VMQ is enabled, a dedicated queue is established on the physical network adapter for each virtual network adapter that has requested a queue. As packets arrive for a virtual network adapter, the physical network adapter places them in that network adapter's queue. When packets are indicated up, all the packet data in the queue is delivered directly to the virtual network adapter. Packets arriving for virtual network adapters that don't have a dedicated queue, as well as all multicast and broadcast packets, are delivered to the virtual network in the default queue. The virtual network handles routing of these packets to the appropriate virtual network adapters as it normally would.
Switch Embedded Teaming Switch-embedded Teaming (SET) merges the NIC Teaming capabilities into the SDN switch. In addition, using SET, a user may team RDMA-capable NICs without giving up their RDMA capabilities. Also using SET, a user may team SR-IOV NICs without giving up their SR-IOV capabilities.
Host RDMA The Host RDMA feature provides the Network Direct Kernel consumer interface at the management or other virtual NIC (vNIC) exposed to the host partition. This enables, for example, SMB Direct to work over vNICs instead of requiring separate RDMA-capable physical NICs.
Cloud Ready Additional Qualification This qualification only applies for Ethernet devices that support line rates of 10 Gigabits per second (Gbps) and above, are built for Server use, have the features and comply w/ the specifications listed below, and have been validated to able to handle the stress requirements of a data center. The required Features and Specifications are:
  • Send checksum (IPv4, TCP, UDP)
  • Receive checksum (IPv4, TCP, UDP)
  • RSS
  • RSC
  • LSOv2
  • VMQ
  • NV-GRE
  • RDMA (iWARP or Routable RoCE), Host RDMA
  • VxLAN TO
  • Packet Direct (PD)
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