Re: [lwip-users] Duplicated ACK and retransmitted packets - some news

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Lou Cypher wrote:
> And the best I can have is an
>   "Optional dual buffer memories, 4K byte ping-pong,
>    for Tx and Rx"
> So buffering at most *two* incoming packets.
>
> Have to confess I never made a deep survey on silicon vendors' choices, at MAC
> level, in the various devices (i.e. MCUs).
> Taking the data sheet of an Ethernet enabled (integral MAC) MCU I see how their
> buffering is "smarter", using some buffer descriptors, separating many variable
> length packets in a FIFO.
> If I return back to the FPGA ip-core, well, no signs of intelligent life, on
> that planet (...)
>    
The MAC you have for your FPGA is OK, only what you're missing is a DMA 
engine. There are ip-core MACs including a DMA engine and there are 
those not including it - you can still write your own DMA engine for the 
MAC (especially if you need special handling in it). For a DMA-engine, 
double-buffering is enough as long as the internal data bus is faster 
DMA-ing received frames into RAM than receiving the next packet.

Of course, writing a DMA for the MAC is not done in a day, either...

Simon