ESP32 Forum

Hello all,

I have a mqtt applecation using esp32 board.

I have 2 questions:

1) In which document can I find information about the MTU WIFI size of an ESP32? I have googled that and in the other forums they say 1500 Byte but I cant find the Information in the datasheet or in a specific document.

2) The maximum mqtt message size is 256 MB that means we can send 256 MB messages with mqtt but at the same time we are limited by the MTU size so that we can max send 1500 Byte messages. Do I understand this correctly?


Thanks in advance

regards
msawaf

Yes. Note you can send packets larger than 1500 bytes, they'll simply get sent in chunks of 1500 bytes and reassembled automatically on the other side.

ESP_Sprite wrote: ↑

Thu Nov 18, 2021 3:02 am

Yes. Note you can send packets larger than 1500 bytes, they'll simply get sent in chunks of 1500 bytes and reassembled automatically on the other side.

so no data will be lost right?

But I think getting the data in chunks and reassembled the data will slow dow the speed connection is that right?

No data will be lost. Not sure what you compare the speed to when you say 'will slow down the speed'... there's no way to get a greater MTU as it's a property of the WiFi protocol, not specifically of the ESP32.