On a vSphere Distributed Switch 5.x, and on a vSphere Distributed Switch upgraded to 6.0 that does not have Network I/O Control enhanced to version 3, you can ensure that system traffic and virtual machines receive required bandwidth for their operation by using the resource pool model of Network I/O Control version 2.

Network Resource Pools in Network I/O Control Version 2

In Network I/O Control version 2, distributed switch traffic supports two types of network resource pools:

  • System network resource pools. Predefined pools for controlling the network bandwidth provided to the main types of system traffic: Fault Tolerance traffic, iSCSI traffic, vMotion traffic, management traffic, vSphere Replication traffic, NFS traffic, and virtual machine traffic.

  • User-defined network resource pools. Custom pools for virtual machine traffic. The settings in a user-defined resource pool are applied to virtual machines after you associate a user-defined resource pool with a distributed port group.

Bandwidth Allocation Parameters for Network Resource Pools in Network I/O Control Version 2

Parameter for Bandwidth Allocation



When a physical adapter is saturated, the virtual machines or VMkernel adapters that use the adapter receive bandwidth to the external network according to the shares configured on the network resource pool.

The physical adapter shares that are assigned to a network resource pool determine the share of the total available bandwidth guaranteed to the traffic associated with that network resource pool. The actual share of bandwidth for outgoing traffic available to a network resource pool is determined by the shares of the network resource pool and what other network resource pools are actively transmitting.

For example, you assign 100 shares to vSphere FT traffic and iSCSI traffic, while each of the other network resource pools has 50 shares. A physical adapter is configured to send traffic for vSphere Fault Tolerance, iSCSI and management. At a certain moment, vSphere Fault Tolerance and iSCSI are the active traffic types on the physical adapter and they use up its capacity. Each traffic receives 50% of the available bandwidth. At another moment, all three traffic types saturate the adapter. In this case, vSphere FT traffic and iSCSI traffic obtain 40% of the adapter capacity, and vMotion 20%.


The iSCSI traffic resource pool shares do not apply to iSCSI traffic on a dependent hardware iSCSI adapter.


The host limit of a network resource pool is the maximum bandwidth that the traffic associated with the network resource pool can consume on a physical adapter.

QoS tag

Assigning a QoS priority tag to a network resource pool applies an 802.1p (CoS) tag to all outgoing packets associated with that network resource pool. In this way, you can mark certain traffic so that network devices, such as switches, can handle it with higher priority.