Speed Problem

Question

I am using W5300 device with spartan 6 FPga. I can send and receive data correctly with out error. But my problem is that the data rate in TCP connection is not more than 6~ 9 Mbps while connection is 100Mbps. The Bit rate change has been done by change in clock speed in processes for controlling W5300. but when the clock exceeded from 25Mhz, every thing stopped. i would be thank full if some body help me. Thank you

Eugeny · Answer

WIZnet declares that W5300 max speed is 80 Mbps; Access time per the datasheet should be 65+28 ns and 50+28 ns between falling edges of the CS in parallel read and write modes respectively. It gives max throughput 86 Mbps in 8-bit mode, very close to WIZnet declared value; Throughput will greatly depend on what is going on the network. Did you analyze the real stream using Wireshark? Throughput will also greatly depend on the algorithm you use to access W5300; I assume you use no-delayed ACK in TCP mode?

Eugeny · Answer

meysam: On the third part of your answer you mentioned whats going on network. you mean ack response? I mean everything what is going on the network potentially speeding down the useful communication. Packet retransmit, delays within network, delays in the network devices etc. All this can be found out by tracing the Wireshark log. meysam: Could you please help me more about the proper algorithm? Review chapter 5 of the datasheet, it has explanation of the basic algorithms used to communicate with W5300. You task is to ensure you comply to them (should be the case as it works for you), but also ensure you do not create unneeded delays during chip communication (as you may be surprised that data transmission speed may be more affected by internal device processing, and not much outer networking environment). meysam: I have use no-delayed ACK in TCP mode. Does this mode limit speed? No, it removes delay in W5300 operation. Continue using it in this mode.

meysam · Answer

Thank you Dear Eugeny I will check your notifications and send you back the results