6.5.1

Table 11‑3. Allocation Parameters for System Trac
Parameter for Bandwidth Allocation Description
Shares Shares, from 1 to 100, reflect the relative priority of a system
traffic type against the other system traffic types that are active
on the same physical adapter.
The amount of bandwidth available to a system traffic type is
determined by its relative shares and by the amount of data that
the other system features are 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%.
Reservation The minimum bandwidth, in Mbps, that must be guaranteed on a
single physical adapter. The total bandwidth reserved among all
system traffic types cannot exceed 75 percent of the bandwidth
that the physical network adapter with the lowest capacity can
provide.
Reserved bandwidth that is unused becomes available to other
types of system traffic. However, Network I/O Control does not
redistribute the capacity that system traffic does not use to
virtual machine placement. For example, you configure a
reservation of 2 Gbps for iSCSI. It is possible that the distributed
switch never imposes this reservation on a physical adapter
because iSCSI uses a single path. The unused bandwidth is not
allocated to virtual machine system traffic so that Network I/O
Control can safely meet a potential need for bandwidth for
system traffic, for example, in the case of a new iSCSI path
where you must provide bandwidth to a new VMkernel adapter .
Limit The maximum bandwidth, in Mbps or Gbps, that a system traffic
type can consume on a single physical adapter.
Example Bandwidth Reservation for System Trac
The capacity of the physical adapters determines the bandwidth that you guarantee. According to this
capacity, you can guarantee minimum bandwidth to a system feature for its optimal operation.
For example, on a distributed switch that is connected to ESXi hosts with 10 GbE network adapters, you
might configure reservation to guarantee 1 Gbps for management through vCenter Server, 1 Gbps for
iSCSI storage, 1 Gbps for vSphere Fault Tolerance, 1 Gbps for vSphere vMotion traffic, and 0.5 Gbps for
virtual machine traffic. Network I/O Control allocates the requested bandwidth on each physical network
adapter. You can reserve no more than 75 percent of the bandwidth of a physical network adapter, that is,
no more than 7.5 Gbps.
vSphere Networking
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