Packet Masking

The following NTPL example configures the SmartNIC to mask out 16 bytes in the layer 4 payload of a frame.

Define maskRecipe = Mask(Offset0=Layer4Payload[0], Length0=16)
Assign[StreamId=0;Mask=maskRecipe] = Layer4Protocol==TCP

Two elements are used to configure the field for packet masking.

• Offset0=Layer4Payload[0]: The starting byte which is specified using a dynamic offset and a static offset where a dynamic offset is based on a predefined protocol layer, and a static offset is relative to the dynamic offset. In this example, Layer4Payload is the dynamic offset and [0] is the static offset. The starting byte is byte 0 of the layer 4 payload.
  Note: Supported static offset values are -16384 to 16383.
• Length0=16: The length of the field in bytes. A maximum of 16 bytes can be configured.

A maximum of 4 fields are supported as shown in the following example.

Define maskRecipe = Mask(Offset0=StartOfFrame[0], Length0=16, Offset1=StartOfFrame[32], Length1=16, \\
Offset2=StartOfFrame[64], Length2=16, Offset3=StartOfFrame[96], Length2=16)
Assign[StreamId=0;Mask=maskRecipe] = Port==0