TcModifyFlow function (traffic.h)

Article
10/13/2021

The TcModifyFlow function modifies an existing flow. When calling TcModifyFlow, new Flowspec parameters and any traffic control objects should be filled.

Traffic control clients that have registered a ModifyFlowComplete handler (a mechanism for allowing traffic control to call the ClModifyFlowComplete callback function in order to alert clients of completed flow modifications) can expect a return value of ERROR_SIGNAL_PENDING.

Syntax

ULONG TcModifyFlow(
  [in] HANDLE       FlowHandle,
  [in] PTC_GEN_FLOW pGenericFlow
);

Parameters

[in] FlowHandle

Handle for the flow, as received from a previous call to the TcAddFlow function.

[in] pGenericFlow

Pointer to a description of the flow modifications.

Return value

Return code	Description
NO_ERROR	The function executed without errors.
ERROR_SIGNAL_PENDING	The function is being executed asynchronously; the client will be called back through the client-exposed ClModifyFlowComplete function when the flow has been added, or when the process has been completed.
ERROR_INVALID_HANDLE	The interface handle is invalid.
ERROR_NOT_ENOUGH_MEMORY	The system is out of memory.
ERROR_NOT_READY	Action performed on the flow by a previous function call to the TcAddFlow, TcModifyFlow, or TcDeleteFlow has not yet completed.
ERROR_INVALID_PARAMETER	A parameter is invalid.
ERROR_INVALID_SERVICE_TYPE	An unspecified or bad intserv service type has been provided.
ERROR_INVALID_TOKEN_RATE	An unspecified or bad TokenRate value has been provided.
ERROR_INVALID_PEAK_RATE	The PeakBandwidth value is invalid.
ERROR_INVALID_SD_MODE	The ShapeDiscardMode is invalid.
ERROR_INVALID_QOS_PRIORITY	The priority value is invalid.
ERROR_INVALID_TRAFFIC_CLASS	The traffic class value is invalid.
ERROR_NO_SYSTEM_RESOURCES	There are not enough resources to accommodate the requested flow.
ERROR_TC_OBJECT_LENGTH_INVALID	Bad length specified for the TC objects.
ERROR_INVALID_DIFFSERV_FLOW	Applies to Diffserv flows. Indicates that the QOS_DIFFSERV object was passed with an invalid parameter.
ERROR_DS_MAPPING_EXISTS	Applies to Diffserv flows. Indicates that the QOS_DIFFSERV_RULE specified in TC_GEN_FLOW already applies to an existing flow on the interface.
ERROR_INVALID_SHAPE_RATE	The QOS_SHAPING_RATE was passed with an invalid ShapeRate.
ERROR_INVALID_DS_CLASS	QOS_DS_CLASS is invalid.
ERROR_NETWORK_UNREACHABLE	The network cable is not plugged into the adapter.

Remarks

If the TcModifyFlow function returns ERROR_SIGNAL_PENDING, the ClModifyFlowComplete function will be called on a different thread than the thread that called the TcModifyFlow function.

Note Use of the TcModifyFlow function requires administrative privilege.

Requirements

Requirement	Value
Minimum supported client	Windows 2000 Professional [desktop apps only]
Minimum supported server	Windows 2000 Server [desktop apps only]
Target Platform	Windows
Header	traffic.h
Library	Traffic.lib
DLL	Traffic.dll