Introduction
This chapter includes the following sections:
- Overview of Virtualization
- Overview of Cisco Virtual Machine Fabric Extender
- Virtualization with a Virtual Interface Card Adapter
- VM-FEX for Hyper-V
Overview of Virtualization
Virtualization allows you to create multiple Virtual Machines (VMs) to run in isolation, side by side on the same physical machine.
Each virtual machine has its own set of virtual hardware (RAM, CPU, NIC) upon which an operating system and fully configured applications are loaded. The operating system sees a consistent, normalized set of hardware regardless of the actual physical hardware components.
In a virtual machine, both hardware and software are encapsulated in a single file for rapid provisioning and moving between physical servers. You can move a virtual machine, within seconds, from one physical server to another for zero-downtime maintenance and continuous workload consolidation.
The virtual hardware makes it possible for many servers, each running in an independent virtual machine, to run on a single physical server. The advantages of virtualization include better use of computing resources, greater server density, and seamless server migration.
Overview of Cisco Virtual Machine Fabric Extender
A virtualized server implementation consists of one or more VMs that run as guests on a single physical server. The guest VMs are hosted and managed by a software layer called the hypervisor or virtual machine manager (VMM). Typically, the hypervisor presents a virtual network interface to each VM and performs Layer 2 switching of traffic from a VM to other local VMs or to another interface to the external network.
Working with a Cisco virtual interface card (VIC) adapter, the Cisco Virtual Machine Fabric Extender (VM-FEX) bypasses software-based switching of VM traffic by the hypervisor for external hardware-based switching in the fabric interconnect. This method reduces the load on the server CPU, provides faster switching, and enables you to apply a rich set of network management features to local and remote traffic.
VM-FEX extends the IEEE 802.1Qbh port extender architecture to the VMs by providing each VM interface with a virtual Peripheral Component Interconnect Express (PCIe) device and a virtual port on a switch. This solution allows precise rate limiting and quality of service (QoS) guarantees on the VM interface.
Virtualization with a Virtual Interface Card Adapter
A Cisco VIC adapter, such as the Cisco UCS M81KR Virtual Interface Card, is a converged network adapter (CNA) that is designed for both single-OS and VM-based deployments. The VIC adapter supports static or dynamic virtualized interfaces, which includes up to 128 virtual network interface cards (vNICs).
VIC adapters support VM-FEX to provide hardware-based switching of traffic to and from virtual machine interfaces.
VM-FEX for Hyper-V
Overview of VM-FEX for Hyper-V
Microsoft Hyper-V is a virtualization package for Windows Server 2012 and later releases on an x86-64 hardware platform. Hyper-V uses x86 hardware virtualization extensions (for example, Intel VT-x) to implement a hypervisor that hosts VMs as userspace processes.
With VM-FEX for Hyper-V, the hypervisor performs no switching of VM traffic. Working with an installed VIC adapter, the hypervisor acts as an interface virtualizer, performing the following functions:
- For traffic going from a VM to the VIC, the interface virtualizer identifies the source vNIC so that the VIC can explicitly tag each of the packets generated by that vNIC.
- For traffic received from the VIC, the interface virtualizer directs the packet to the specified vNIC.
All switching is performed by the external fabric interconnect, which can switch not only between physical ports, but also between virtual interfaces (VIFs) that correspond to the vNICs on the VMs.
Cisco UCS Manager Components
Cluster
The Cisco UCS cluster is a grouping of hypervisors that can be distributed across multiple hosts. In a Hyper-V system, the cluster is analogous to the distributed virtual switch (DVS) in a VMware ESX system.
In the current Cisco UCS Hyper-V implementation, the cluster defines the scope of the port profile and is the boundary of the migration domain. When multiple Hyper-V hosts are associated to a cluster, you can migrate a VM from one host to another within the cluster.
Port Profiles
Port profiles contain the properties and settings that are used to configure virtual interfaces in Cisco UCS. The port profiles are created and administered in Cisco UCS Manager. After a port profile is created, assigned to, and actively used by a cluster, any changes made to the networking properties of the port profile in Cisco UCS Manager are immediately applied to the cluster with no need for a host reboot.
Port Profile Client
The port profile client is a cluster to which a port profile is applied.
Single Root I/O Virtualization
Single Root I/O Virtualization (SR-IOV) allows multiple VMs running a variety of guest operating systems to share a single PCIe network adapter within a host server. SR-IOV allows a VM to move data directly to and from the network adapter, bypassing the hypervisor for increased network throughput and lower server CPU burden. Recent x86 server processors include chipset enhancements, such as Intel VT-x technology, that facilitate direct memory transfers and other operations required by SR-IOV.
The SR-IOV specification defines two device types:
- Physical Function (PF)—Essentially a static vNIC, a PF is a full PCIe device that includes SR-IOV capabilities. PFs are discovered, managed, and configured as normal PCIe devices. A single PF can provide management and configuration for a set of virtual functions (VFs).
- Virtual Function (VF)—Similar to a dynamic vNIC, a VF is a full or lightweight virtual PCIe device that provides at least the necessary resources for data movements. A VF is not managed directly but is derived from and managed through a PF. One or more VFs can be assigned to a VM.
SR-IOV is defined and maintained by the Peripheral Component Interconnect Special Interest Group (PCI-SIG), an industry organization that is chartered to develop and manage the PCI standard. For more information about SR-IOV, see the following URL:
Hypervisors that support SR-IOV include Linux KVM and Microsoft Hyper-V.
The following Cisco Virtual Interface Cards support SR-IOV with VM-FEX:
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