6.5.1

Table Of Contents
About vSphere Network I/O Control Version 3
vSphere Network I/O Control version 3 introduces a mechanism to reserve bandwidth for system traffic
based on the capacity of the physical adapters on a host. It enables fine-grained resource control at the
VM network adapter level similar to the model that you use for allocating CPU and memory resources..
Version 3 of the Network I/O Control feature offers improved network resource reservation and allocation
across the entire switch.
Models for Bandwidth Resource Reservation
Network I/O Control version 3 supports separate models for resource management of system traffic
related to infrastructure services, such as vSphere Fault Tolerance, and of virtual machines.
The two traffic categories have different nature. System traffic is strictly associated with an ESXi host. The
network traffic routes change when you migrate a virtual machine across the environment. To provide
network resources to a virtual machine regardless of its host, in Network I/O Control you can configure
resource allocation for virtual machines that is valid in the scope of the entire distributed switch.
Bandwidth Guarantee to Virtual Machines
Network I/O Control version 3 provisions bandwidth to the network adapters of virtual machines by using
constructs of shares, reservation and limit. Based on these constructs, to receive sufficient bandwidth,
virtualized workloads can rely on admission control in vSphere Distributed Switch, vSphere DRS and
vSphere HA. See Admission Control for Virtual Machine Bandwidth.
Network I/O Control Version 2 and Version 3 in vSphere 6.0
In vSphere 6.0, version 2 and version 3 of the Network I/O Control coexist. The two versions implement
different models for allocating bandwidth to virtual machines and system traffic. In Network I/O Control
version 2, you configure bandwidth allocation for virtual machines at the physical adapter level. In
contrast, version 3 lets you set up bandwidth allocation for virtual machines at the level of the entire
distributed switch.
When you upgrade a distributed switch, the Network I/O Control is also upgraded to version 3 unless you
are using some the features that are not available in Network I/O Control version 3, such as CoS tagging
and user-defined network resource pools. In this case, the difference in the resource allocation models of
version 2 and version 3 does not allow for non-disruptive upgrade. You can continue using version 2 to
preserve your bandwidth allocation settings for virtual machines, or you can switch to version 3 and tailor
a bandwidth policy across the switch hosts.
vSphere Networking
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