Network byte order used e.g. by TCP is big endian. This doesn't effect the actual payload the user is sending over the network, does it? This is in regards to the e.g. 16-bit port number and a 32-bit IPv4 address, which TCP exchanges itself and thus requires the participants to agree on endianness.
In other words: Assuming 2 participants with same endianness machines and a simple setup with TCP sockets, there is no need to convert anything in terms of data/payload, right?
I'm just a little confused as there is a lot of talk regarding endianness conversion with regards to network byte order. For example, in IBM's docs (IBM Docs Network Byte Order) it says:
The TCP/IP standard network byte order is big-endian. In order to participate in a TCP/IP network, little-endian systems usually bear the burden of conversion to network byte order.
To me this sounds like conversion depends on network byte order when in fact the only thing that matter are the endianness on the participating machines, doesn't it.
This doesn't effect the actual payload the user is sending over the network, does it?
TCP and UDP just transport bytes without any inherent meaning. How the payloads needs to be interpreted and if endianness is relevant is part of the application layer, i.e. depends on the application protocol spoken.