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DM648 3port switch ethernet subsystem Max Linerate

SP
Prodigy 200 points

I use the 3PSW Ethernet Subsystem on DM648 on my custom board with the following configuration settings.

REFCLKP/N:62.5 MHz, MPY: 20x, RATE: Half making the Line rate to 1250MHz.

Is 1250MHz the max possible line rate acheivable on DM648? I know that the multiplier can be set to a max value of 25x and REFCLK to 125MHz and RATE to Full. But not sure the DM648 will work in this combination of settings..

Also, currently the DM648 in my application receives a maximum payload size of 1472 bytes per packet (excluding the protocol headers) from host to which it is connected over ethernet. Does DM648 support receiving packets greater than 1500 bytes?

SP

  • 0
    Prodigy 200 points
    Any quick response to my query above is appreciated..
  • 0
    TI__Guru** 116100 points
    Hi,


    Also, currently the DM648 in my application receives a maximum payload size of 1472 bytes per packet (excluding the protocol headers) from host to which it is connected over ethernet. Does DM648 support receiving packets greater than 1500 bytes?

    Regarding Jumbo packet support (>=1500), please refer to the following TI wiki page.

    processors.wiki.ti.com/.../Network_Developers_Kit_FAQ
  • 0
    TI__Mastermind 43660 points

    Hello SP,

    I use the 3PSW Ethernet Subsystem on DM648 on my custom board with the following configuration settings.

    REFCLKP/N:62.5 MHz, MPY: 20x, RATE: Half making the Line rate to 1250MHz.

    Is 1250MHz the max possible line rate acheivable on DM648? I know that the multiplier can be set to a max value of 25x and REFCLK to 125MHz and RATE to Full. But not sure the DM648 will work in this combination of settings..

    Yes, the max. possible line rate achievable on DM648 is 1250MHz only. Please refer the below 3PSW Ethernet Subsystem user guide section 1.4 Clocks where you can find the possible suggested combinations between MPY, RATE, REFCLKP/ N, and the corresponding Line Rate.

    http://www.ti.com/lit/ug/spruf57b/spruf57b.pdf

    Regards,

    Senthil

  • 0 in reply to Titusrathinaraj Stalin
    Prodigy 200 points

    Hi Titu,

    The wiki page tells..

    "However, the hardware does not support Jumbo Frames (typically around 9000 bytes but can assume any value), since the DM648 EMAC peripheral has a limitation to receive frames up to 2047 bytes (headers included). This is still above the standard value of 1518 bytes."

    I hope the DM648 EMAC peripheral can receive as well as transmit a maximum of 2047 bytes per packet..

    The wiki page also tells that:

    "Even so, all NDK releases can transmit regular sized packets faster than 100 Mbps."

    What does regular sized packets mean? If i transmit/receive 2047 bytes per packet, what is the maximum Ethernet speed achievable? Will i be able to get the configured line rate of 1250Mbps? I am not using NDK since i work on a legacy code base without NDK integrated.

    SP

  • 0 in reply to Senthilkumar Srinivasan
    Prodigy 200 points
    Senthil,

    I don't find any "RATE=Full" entries in the table with possible suggested combinations between MPY, RATE, REFCLKP/ N and the corresponding Line Rate for the BUSWIDTH of 10. So does it mean that Full rate is not supported in DM648 to acheive more line rate?

    SP
  • 0 in reply to SP
    TI__Mastermind 43660 points
    Hello SP,

    Yes, the maximum line rate supported by the device is 1250Mbps and you can not change the RATE to increase the line rate beyond 1250Mbps. The recommended combinations have been tested and validated. To my knowledge, we have not tested the full rate and that is why it is not listed in the recommended listing.

    Hope it helps.

    Regards,
    Senthil
  • 0 in reply to SP
    Prodigy 200 points
    Hello Titus.. Could you please give me a reply?

    SP