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Network I/O Resource Management in vSphere 4.1 and vSphere 5.x with vDS (1022585)

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This article describes the Network I/O Resource Management feature in vSphere 4.1 and vSphere 5.x with vDS.


Network I/O Resource Management (NetIORM) controls traffic dynamically. It can improve network traffic in congested environments, guarantee bandwidth (based on shares and available bandwidth in total, and restrict particular traffic.
To control the traffic, there are seven pre-defined network resource pools:
  • vMotion 
  • NFS
  • iSCSI 
  • FT
  • Management
  • Virtual machine 
  • vSphere Replication (VR) (vDS 5.x only)
These network resource groups are based on the vDS ports, not on network ports (such as TCP or UDP ports). With the connection to a specified port, the traffic on this port belongs to one of these pre-defined groups. If you mount an NFS share inside a virtual machine it is treated as virtual machine traffic instead of NFS traffic.
Network Resource pools have two configurable values:
  • Shares
  • Limits


Shares work like the shares on virtual machines (CPU, Memory). The Network Resource Management sums up all shares and set the shares in relation to the sum. A value of 50 does not necessarily mean the group is entitled for 50% of bandwidth (although it could be possible if the shares of the other groups sum up to 50, too). Unused traffic from one group can dynamically be used by other groups if needed.

  • Normal = 50
  • Low = 25
  • High = 100
  • Custom = any values between 1 and 100

Default values:

  • Virtual machine traffic = High (100)
  • All other = Normal (50)
  • No limit set
Note: Shares work only in case of congestion in the network interfaces.


Limits limit traffic on the host to the configured rate, implemented as a hard limit per host. No limit is set by default, and no burst is allowed like a limit in traffic shaping.
Note: Even with different pNIC speeds, limits are calculated on a per host basis. If limit > pNIC speed, pNIC speed is the limitation.
Implementation details:
  • Each host calculates the shares separately. One host may have 1Gbit/s NICs, while another has 10Gbit/s NICs. As such, the resulting guaranteed bandwidth is different.
  • Only outgoing traffic is controlled.
  • Intra-switch traffic is not controlled. Only the pNICs are affected.
  • Limits are still valid even if the pNIC is opted out.

Additional Information

If you need to separate or control traffic for some virtual machines, use traffic shaping as you would in earlier versions of ESX. For more information about traffic shaping, see VMware Virtual Networking Concepts.

See Also

Request a Product Feature

To request a new product feature or to provide feedback on a VMware product, please visit the Request a Product Feature page.


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  • 28 Ratings