Frame Characteristics

Napatech Link™ Software Features

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Intel® PAC
Napatech SmartNIC
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Feature Description

In this section

This section describes various ways of characterizing frames.

Decodings

This table describes the frame decodings.

Category Description
Small The frame is smaller than 64 bytes.
Giant undersize The frame is larger than or equal to 64 bytes including tags, and smaller than 64 bytes when the present tags/labels (ISL, MPLS and VLAN) are removed.
Baby giant The frame is larger than the value of MaxFrameSize (see MaxFrameSize) including tags, and smaller than the value of MaxFrameSize when the present tags/labels (ISL, MPLS and VLAN) are removed.
Large The frame is a large frame (see Large frames).
Hard-sliced The frame is larger than 10000 bytes.

MaxFrameSize

MaxFrameSize is a parameter in the ntservice.ini file (see DN-0449). The range is 1518 bytes to the maximum frame size (10,000 bytes) supported by the SmartNIC. The setting affects statistics only and not necessarily frame dropping. The default value is 9018.

Interpretations

In line with the RMON and IEEE 802.3 standards only frames with proper framing, that is with a proper SFD (start frame delimiter), are counted. Since frames without a proper SFD are not recognized as frames and are not forwarded to the host, they are not counted.

All frames received by the host, both good and bad frames, including hard-sliced frames are counted in a frame counter as well as a byte counter.

The counters reflect the full raw frame including any tags (ISL, VLAN and MPLS), but excluding Preample and Start Frame Delimiter bytes.

Good/bad frames

A frame is a good frame if it is not a bad frame.

A frame is a bad frame if it is small, large or hard-sliced, or if there is a CRC error or a code violation. This interpretation is used as it seems reasonable to handle code violation in the same way as CRC errors since both are usually generated by noise.

Note: Since hard-sliced frames are large, they are also bad frames.
Note: CRC is only checked for frames with up to 10,000 bytes, and CRC errors are always indicated for longer frames.
Note: CRC errors are always indicated for frames smaller than 18 bytes, since they are considered as fragments.

Hard-sliced frames

Frame length for hard-sliced frames is the wire length determined by the MAC, that is 10 kbytes.