Is the PID sent along with the packet or not?

Question

Computer networks

A teacher at our university states that the PID (Process ID) is sent in one of the packet headers.
Those. IP, port and PID are used for addressing.
I went through the main RFC standards of the network, transport, application layer and nowhere is it said about sending a PID.
Yes, and everywhere it is written that the port is the end point of addressing.
He does not want to take my word for it, and the documents confirming this are not googled (
Where can I find documents that describe how this actually happens?

Answer 1

Take Wireshark traffic from a process with a known PID, look at this PID in the raw data. In general, the burden of proof lies with the approver, so ask the teacher to show the corresponding bytes in the same Wireshark.

Answer 2

First, you didn't specify which protocol you are talking about. Although this is hardly important in this context.
Secondly, it is not clear what standards you wool. If you follow a simple path and open Wikipedia, then you can see the composition of the packets there, for example, TCP and UDP (since the protocol is not clear from the context, we take them).
TCP: https://ru.wikipedia.org/wiki/TCP#.D0.97.D0.B0.D0....
UDP: https://ru.wikipedia.org/wiki/UDP#.D0.A1 .D1.82.D1....
Of course, PID is not used for data exchange with external sources (if we are talking about some classic schemes). First, the operating system knows which process is listening on which port. That is, if the port is known, then the PID is not needed. Secondly, the same process can listen on different ports. That is, the PID for the external source is not a unique identifier, but the port is.
Total:
In classical transport protocols - no, it is not sent. It's just useless information for networking.

Answer 3

At the network (IP) and transport (UDP, TCP) level, pid is not transmitted. The process to which we assign the received data of the transport layer is determined by the listening socket that belongs to it, which is determined by the IP address, protocol and port.