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DP83816: Packet size

Part Number: DP83816

Hi Team,

Please give me advise on relationship between Descriptor size Ether packet size of the DP83816.

When 64 bytes Ether pact comes in and out from DP83816, the descriptor size is 0x600 = 1536 bytes despite of 64 bytes.

Is the minimum descriptor size 1536 regardless of small packet?

 

Please also let me know the detail structure of the recorded data?

Is it consist of : Destination MAC Address (6bytes) + Source MAC Address (6 bytes)  + Data type (2 bytes) + Data size (2 bytes)  + data (46~1500 bytes)?

Best Regards

Kenji

  • Hi Kenji-san,

    PHY looks for SFD and EFD only. Packet size is driven by MAC and Applications, PHY is transparent.

    Regards,

    Geet

  • Hi Geet,

    I understand that the DP83816 is a MAC + PHY device.

    ”DP83816 10/100 Mb/s Integrated PCI Ethernet Media Access Controller and Physical Layer”

    If my understanding seems correct, answer the packet size question.

    If the description on the datasheet is incorrect, please revise it ASAP.

    I have another question.

    I don't know the meaning of EFD. Can you tell me about EFD?

    Best Regards,

    Kenji

  • Hi Kenji-san,

    Sorry I mis-interpreted this with other part.

    From the buffer management section of the datasheet, I see it ask for 32 byte boundary for the recieve but not for transmit.

    "32-bit pointer to the first fragment or buffer. In transmit descriptors, the buffer can begin on any byte boundary. In receive descriptors, the buffer must be aligned on a 32-bit boundary."

    Can you please point me the location where you find that 

    'When 64 bytes Ether pact comes in and out from DP83816, the descriptor size is 0x600 = 1536 bytes despite of 64 bytes."

    As you know this part is NRND and I hope you are looking this information for an existing customer design using this part.

    Regards,
    Geet

  • Hi,

    I am closing this thread. In case you need further assistance, please open new thread and provide reference to this thread.

    Regards,

    Geet

  • Hi Geet-san,

    Let me check again.
    Packets that exceed 1518 bytes should be discarded by the device, but descriptor size is 0x600 = 1536 bytes.
    Can a descriptor exceed 1518 bytes?
    Best Regards,
    Kenji
  • From descriptior, it shall be within 1512 bytes.

    Please help answer the other questions in my earlier thread as the part is NRND.

    Regards,

    Geet

  • Hi,

     

    I am closing this thread. In case you need further assistance, please open new thread and provide reference to this thread.

     

    Regards,

    Geet