Assigning Traffic to Streams

Assigning traffic to streams

The streams that the traffic should be distributed to are specified by giving a range or list of streams as StreamId argument in one or more Assign NTPL commands.

Traffic that is not assigned to any stream will be dropped.

By default, traffic is distributed to a set of streams using a round robin algorithm.

Simple distribution example

In this example, all traffic will be distributed in round robin fashion between streams 0, 1, 2, 3, 4, 5 and 6.

Assign[StreamId=(0..6)] = All

Configuring host buffers

For forwarding traffic to multiple host buffers and streams, host buffers must be configured in the ntservice.ini file. To edit the ntservice.ini file, run the following command.

vim /opt/napatech3/config/ntservice.ini

By default, host buffers are configured as follows.

NumaNode = -1
HostBuffersRx = [4,16,-1]

Four 16-Mbyte host buffers are configured on the NUMA node taken from the NumaNode value. NUMAnode = -1 means that the driver attempts to determine the NUMA node location of the SmartNIC. Set the number of the RX host buffers to a desired number. For example:

HostBuffersRx = [8,16,-1]

ntservice must be stopped and restarted for changes to take effect.

/opt/napatech3/bin/ntstop.sh
/opt/napatech3/bin/ntstart.sh

For more information on configuration parameters in the ntservice.ini file, see ntservice ini file in DN-0449.

Setting network stream limits

To use more than 256 network streams, the MaxNetStreams and MaxStreamIds parameters should be configured. For example:

MaxNetStreams = 1024
MaxStreamIds = 512

MaxNetStreams = 1024 indicates total stream capacity across RX and TX. In this example, RX streams and TX streams can be 512 each, for a total of 1024 streams.
MaxStreamIds = 512 indicates the valid stream ID range. In this example, stream IDs 0 to 511 are valid.

Note: The value of MaxNetStreams must be chosen based on the number of SmartNICs installed in the server and the design of the application. Each SmartNIC consumes RX and TX network stream resources, and applications that open multiple network streams must ensure that MaxNetStreams is configured high enough to support their expected usage.

For more information on configuration parameters in the ntservice.ini file, see ntservice ini file in DN-0449.