Appendixes

CentOS

An open source Linux distribution that reuses source code from Red Hat Enterprise Linux.

CPU Pinning

A configuration constraint (often expressed as an affinity map), which specifies to the scheduler the (logical) cores that can be used to run a task or set of tasks.

Distributed Model

vSIM instance that uses two or more VMs, connected to a common internal network, to implement a single network element.

Haswell

Intel CPU micro-architecture introduced in 2013 that uses 22-nm process.

Huge pages

A large block (2MB or 1GB) of physically contiguous virtual memory that has a mapping (in the page table) to physical memory.

Hyper-threading

Intel technology that presents one physical CPU core as two logical processors to the OS.

Hypervisor

Software running on a host machine that creates and manages VMs, and provides the guest O/S in each VM with an abstraction of the physical machine.

See also VMM.

Integrated model

A vSIM instance that uses a single VM to support all the functions of one network element.

Intel VT-d

Intel Virtualization Technology for Directed I/O

Intel CPU MMU feature that provides hardware assist for mapping a guest virtual address (GVA) to a guest physical address (GPA) to a host physical address (HPA). Avoids the need for VMM to maintain a shadow page table per guest.

Intel VT-x

Intel Virtualization Technology for x86 processors

Hardware virtualization support in Intel CPUs that allows guest OS to run natively on x86. Introduces two new CPU modes: VMX root (intended for host/VMM execution) and VMX non-root (intended for guest).

Kernel Space

A block of virtual memory strictly reserved for the OS kernel, kernel extensions and device drivers.

KVM

Kernel-based Virtual Machine

Linux kernel module that allows a user space program, such as QEMU, to access the hardware virtualization features of the CPU.

L3 Cache

Fast on-chip memory of the CPU that stores frequently accessed data, saving time to access main memory. It is shared by all cores of the CPU.

Libvirt

Open source Linux package that provides a common set of APIs for creating and managing the VMs on one host, independent of hypervisor. Libvirt uses XML files to define the properties of VM instances, networks, and other devices; the virsh command line toolset is provided.

Linux Bridge

Software implementation of a bridge that forwards Ethernet frames based on destination MAC address; bridging is performed by a kernel module controlled by the brctl userspace program installed with the bridge-utils package. A Linux bridge is supported by various Linux OS.

MANO

Management and Orchestration

A reference architecture defined by ETSI NFV study group that gives generic names to the functional components of a complete NFV solution.

NUMA

Non-Uniform Memory Access

An optimization for multi-CPU systems where each processor has its own memory.

OpenStack

An open source cloud orchestration platform (VIM) managed by the non-profit OpenStack Foundation, it includes various components such as Nova (compute), Neutron (networking), Glance (image service), Cinder (block storage), and Dashboard (GUI).

OVA

Open Virtual Application

A tar archive of an OVF package.

OVF

Open Virtualization Format

A DMTF standard format for packaging software to be run in VMs. An OVF package contains an XML-based OVF descriptor file (.ovf), one or more disk images, and other auxiliary files. The OVF descriptor file specifies HW requirements and lists references to other files in the OVF package.

OVS

Open Virtual Switch

Open-source software implementation of a multi-layer switch, it supports standard bridging protocols, monitoring protocols (sFlow, Netflow), and programmatic extensions (Openflow, OVSDB).

Main OVS components are: userspace daemon (ovs-vswitchd), database daemon (ovsdb-server), and kernel module.

The kernel module implements 'fast path' using a flow cache table populated by ovs-vswitchd. The first packet of a flow goes to ovs-switchd for slow-path processing. ovs-vswitchd communicates with the kernel using the netlink protocol, and with ovsdb-server using the OVSDB protocol.

Release is 2.3.1 is the latest stable OVS release.

Paravirtualization

Technique where the guest and hypervisor coordinate to optimize performance in a virtualized environment.

QCOW2

A virtual disk image format supported by QEMU.

QEMU

Quick Emulator

Open source hypervisor typically used with KVM that emulates a broad range of devices including CPUs, disks, PCIe chipsets, USB devices, and serial ports.

RHEL

Red Hat Enterprise Linux

RSS

Receive Side Scaling

A feature supported by some NICs to classify incoming packets into different receive queues based on 5-tuple flow. Each queue has its own interrupt handled by its own core, which may improve receive throughput.

SMBIOS

System Management BIOS

Data structures and access methods for storing and reading BIOS information.

SR-IOV

A PCI-SIG standard that allows a PCIe device to appear as multiple separate PCIe devices, allowing multiple VM vNIC interfaces to share the same physical NIC port for communications.

Ubuntu

A Debian-based common Linux distribution.

User Space

A block of virtual memory where application software and some drivers execute.

VIM

Virtualized Infrastructure Manager

A MANO component responsible for managing the NFV infrastructure including compute, storage, and network resources. OpenStack and CloudStack are typical VIMs.

VirtIO

A paravirtualized I/O framework where buffers are transferred between the guest-side VirtIO driver and the host-side VirtIO driver.

VHost-net

A device driver that runs in the host kernel and performs the virtqueue operations of the host-side VirtIO driver. It delivers higher performance than complete emulation of the host-side VirtIO driver in QEMU (avoids system calls from userspace, supports zero-copy TX operation).

VM

Virtual Machine

VMDK

Virtual Machine Disk

The virtual disk image format used by VMware VMs.

VMware vSphere

A virtualization product suite sold by VMware, it includes ESXi hypervisor, vCenter server, vSphere Web client, and advanced feature add-ons including vMotion, High Availability, Fault Tolerance, Distributed Switch, Distributed Resource Scheduler.

VNFM

VNF Manager

The MANO component responsible for lifecycle management of VNF instances. Coordinates with EMS/NMS. This role is provided by Cloudband CBAM for vSIM instances.

VXLAN

Virtual eXtensible Local Area Network

A method of encapsulating Ethernet frames inside IP/UDP packets to create a tenant-specific overlay network within a data center.

x2APIC

Intel programmable interrupt controller.