Visible to Intel only — GUID: pad1707466000080
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Visible to Intel only — GUID: pad1707466000080
Ixiasoft
4.6.2. Length Checking
The frame length must be at least 64 (0x40) bytes and not exceed the MAX_TX_SIZE_CONFIG on MAC TX or MAX_RX_SIZE_CONFIG on MAC RX. MAC TX/RX does not drop frames or packet data even if an error has been detected. The MAC TX/RX keeps track of the actual payload length as it monitoring a TX/RX frame, and it checks the actual payload length against the length/type or client length/type field.
As the existence of padding when frame length is less than 64 bytes and over-padding when frame length is more than 64 bytes, the MAC TX/RX does not try to match the actual payload length value with the frame length/type field value. The MAC TX/RX marks "payload length error" only when the actual payload length is smaller than the frame length/type or client length/type field.
The MAC TX/RX checks for the following types of length error:
- Undersized frame error: If actual packet frame byte count is less than 64 bytes, the packet are marked as "undersized frame".
- Oversized frame error: If actual packet frame byte count is more than MAX_TX/RX_SIZE_CONFIG, the packet is marked as "oversized frame". This applies to all packets including basic/VLAN/Stacked VLAN or other types of packets.
- Payload length error:
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- Basic Ethernet packet:
- If the length/type field is less than or equal to 1500 bytes, and the actual payload length is smaller than length/type field, the packet is marked as "payload length error".
- If the length/type field is more than 1500 bytes, payload length are not checked. "Payload length error" are not marked to this kind of packets.
- VLAN tagged frames: If the "Vlan dectection" feature is disabled, "payload length error" does not apply to Vlan/Stacked Vlan packets. Otherwise, following rules applies to decide if packet has "payload length error".
- If the length/type field is less than or equal to 1500 bytes, and the actual payload length is smaller than length/type field, the packet are marked as "payload length error".
- If the length/type field is more than 1500 bytes, payload length are not checked. "Payload length error" are not marked to this kind of packets.
- Control packet (0x8808): The "payload length error" does not apply to this type of packet.
- Basic Ethernet packet: