Setting Properties for Flows

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You implement resource controls over flows by setting flow properties. Flows support the following properties:

max-bw – The maximum bandwidth of the datalink that the packets identified with a flow can use. You must set a value within the allowed range of values for the bandwidth of a datalink. See Example 83, Setting Maximum Bandwidth and Priority for a Flow.
priority – The priority with which packets belonging to the specified flow will be processed. The allowed values for the priority property are high, medium, and low. If the priority of a flow is set to high, all the packets belonging to that flow will be processed ahead of other packets on the same link. This property is used to create a flow for applications that are latency sensitive. The default value of this property is medium. See Example 83, Setting Maximum Bandwidth and Priority for a Flow.

Note - Currently, setting the priority property to low from medium has no effect.
hw-flow – Specifies whether the flow is offloaded to the underlying NIC. The possible values of this property are auto, on, and off.
- on means that the flow has been offloaded to the NIC and packet classification for the flow is conducted at the hardware level.
- auto, the default setting, means that the system decides if the flow can be offloaded to the NIC based on the capability of the NIC.
- off means the flow is not offloaded.
Note - If the hw-flow property is set to on, offloading might fail in some cases such as VNIC migration or VNIC failover on a DLMP aggregation if the destination port does not support flow offload. Retaining the default auto setting is a safer configuration.
Currently, only the flows that are defined by specifying all the transport protocols, local or remote IP address, and local or remote port can be assigned the value on for hw-flow. Also, not all NICs support the hw-flow property.
rank – The rank for a flow which you can optionally set. A flow with no rank setting is lower in the lookup order than one with a rank. Rank values range from 1 to 65535. Low numbers place flows higher in the lookup order than high numbers. If multiple flows have overlapping rank values, the tie is broken by following the default system policy. See Overlapping Flows.

Example 83 Setting Maximum Bandwidth and Priority for a Flow

This example shows how to set the maximum bandwidth to 2G and a high priority for the flow http.

$ flowadm set-flowprop -p max-bw=2G http
$ flowadm set-flowprop -p priority=high http

Example 84 Setting hw-flow for a Flow

This example shows how to set the hw-flow property for a flow when the NIC is capable and also when the NIC is not capable of offloading the flows.

$ flowadm show-flowprop -p hw-flow
FLOW        PROPERTY   PERM VALUE        EFFECTIVE    DEFAULT   POSSIBLE
ssh-flow    hw-flow    rw   auto         off          auto      auto,off 

# flowadm set-flowprop -p hw-flow=on ssh-flow
flowadm: failed: cannot set flow property 'hw-flow' on 'ssh-flow': operation not supported

The POSSIBLE field shows only the values auto and off, which means that the NIC is not capable of offloading the flows. Therefore, you cannot set the hw-flow property to on.

$ flowadm show-flowprop -p hw-flow
FLOW        PROPERTY   PERM VALUE        EFFECTIVE    DEFAULT   POSSIBLE
http-flow   hw-flow    rw   auto         on           auto      auto,on,off
 
$ flowadm set-flowprop -p hw-flow=on http-flow

$ flowadm show-flowprop -p hw-flow
FLOW        PROPERTY   PERM VALUE        EFFECTIVE    DEFAULT   POSSIBLE
http-flow   hw-flow    rw   on           on           auto      auto,on,off