6.7

Table Of Contents
In a host that runs virtual machine traffic on top of SR-IOV physical adapters, virtual machine adapters
directly contact the virtual functions to communicate data. However, the ability to configure networks is
based on the active policies for the port holding the virtual machines.
On an ESXi host without SR-IOV, the virtual switch sends external network traffic through its ports on the
host from or to the physical adapter for the relevant port group. The virtual switch also applies the
networking policies on managed packets.
Figure 101. Data and Configuration Paths in the SR-IOV Support of vSphere
IOMMU
PCI Express
Physical network adapter with SR-IOV
PCI Express
Physical network adapter without SR-IOV
Port group
Uplink port
Port association
Data path
Control path
Port group
Uplink port
VMware ESXi
Virtual Switch
Virtual Switch
VM
VM
1
3 4
2 5
VM
VF driver
VM
VF driver
PF
PF driver
PF driver
VF
VF
PF
Data Path in SR-IOV
After the virtual machine network adapter is assigned to a virtual function, the VF driver in the guest
operating system uses the I/O memory management unit (IOMMU) technology to access the virtual
function that must receive or send the data over the network. The VMkernel, that is, the virtual switch in
particular, does not process the data flow, which reduces the overall latency of SR-IOV enabled
workloads.
vSphere Networking
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