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Doc: Add how to configure network MTU size

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Alan Carvalho de Assis 2022-11-01 19:29:58 -03:00 committed by Xiang Xiao
parent 12926ee864
commit fd8647d3dd
1 changed files with 20 additions and 0 deletions
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Documentation/faq/index.rst
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@ -144,3 +144,23 @@ It is important to note that your Ethernet controller driver of your
MCU needs to support CONFIG_ARCH_PHY_INTERRUPT (and implement
``arch_phy_irq()``).
How to define the MTU and MSS for the network packets?
------------------------------------------------------
As you probably know the "MSS = MTU - 40", so you just need to setup the MTU.
If you search for MTU in the menuconfig you will not find it, but you can
setup the MTU using the ``CONFIG_NET_ETH_PKTSIZE`` here::
Networking Support --->
Driver buffer configuration --->
(590) Ethernet packet buffer size
Then just figure it out using this formula:
MTU = NET_ETH_PKTSIZE - 14
MSS = MTU - 40
In this case you have MTU = 590 - 14 => MTU = 576!
And the MSS = 576 - 40 => MSS = 536.