Overview of Cisco Virtual Machine Fabric Extender
Avirtualized server implementation consists of one or more VMs running 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). The hypervisor typically presents a virtual network interface to each VM and performs
Layer2 switching of traffic from a VM to other local VMs or to a physical interface to the external network.
Workingwith a Cisco virtual interface card (VIC) adapter, Cisco VirtualMachine Fabric Extender (VM-FEX)
bypassessoftware-based switching of VM traffic by the hypervisor in favor of external hardware-based
switchingin the fabric interconnect. This method results in a reduced load on the server CPU, faster switching,
andthe ability to apply a rich set of network management features to local and remote traffic.
VM-FEXextends the (prestandard) IEEE 802.1Qbh port extender architecture to the VMs, providing each
VMinterface with a virtual Peripheral Component Interconnect Express (PCIe) device and a virtual port on
aswitch. This solution allows precise rate limiting and quality of service (QoS) guarantees on the VM interface.
Virtualization with Network Interface Cards and Converged Network Adapters
Networkinterface card (NIC) and converged network adapters support virtualized environments with the
standardVMware integration with ESX installed on the server and all virtual machine management performed
throughthe VC.
Portability of Virtual Machines
Ifyou implementservice profiles you retainthe ability to easily move aserver identity from oneserver to
another.After you image the new server, the ESX treats that server as if it were the original.
Communication between Virtual Machines on the Same Server
Theseadapters implement the standard communications between virtual machines on the same server. If an
ESXhost includesmultiple virtual machines, all communications must go through the virtual switch on the
server.
Ifthe system uses the native VMware drivers, the virtual switch is out of the network administrator's domain
andis not subject to any network policies. As a result, for example, QoS policies on the network are not
appliedto any data packets traveling from VM1 to VM2 through the virtual switch.
Ifthe systemincludes another virtual switch, such as theNexus 1000, thatvirtual switch is subjectto the
networkpolicies configured on that switch by the network administrator.
Virtualization with a Virtual Interface Card Adapter
ACisco VIC adapter, such as the Cisco UCS M81KR Virtual Interface Card, is a converged network adapter
(CNA)designed for both single-OS and VM-based deployments. The VIC adapter supports static or dynamic
virtualizedinterfaces, including up to 128 virtual network interface cards (vNICs).
VICadapters support VM-FEX to provide hardware-based switching of traffic to and from virtual machine
interfaces.
Cisco UCS Manager GUI Configuration Guide, Release 2.0
OL-25712-04 41
Virtualization in Cisco UCS