ESP32 Forum

When running ethernet examples on esp32 ethernet dev board, getting following error:

esp.emac: emac_esp32_transmit(231): insufficient TX buffer size[0m

what could be the cause, using latest ESP-IDF SDK.

What example do you run? Anyway, it indicates you are trying to transmit more data than the hardware is able to process, i.e. you are reaching to limit of maximum Ethernet bandwidth of 100 Mbps. In reality it little bit less. You need to limit bandwidth. With default configuration of 10 Tx buffers, stable throughput is around 80 Mbps. If you observe it with iperf, you can experiment with bandwidth limit (-b option). You can also try to increase number of Tx buffers in Kconfig.

Thanks for the reply, Will try the bandwidth option. The example i tried was "basic" example, also tried iperf example, it also gives the same error after a while. I noticed in iperf, ip addresses are zero.

That's strange, "insufficient buffer size error" should not occur in "basic" example! Could you please provide more information about your setup?
- What board do you use?
- What is your exact IDF version?
- Please share logs from "basic" example if insufficient buffer size error occurs.