Who sets the ToS bits?

Question

Computer networks

Probably a stupid question, but I can't figure it out. Do the protocols set the ToS bits or, after all, do they need to be set on the network equipment on their own?

Answer 1

Maybe an application if the OS allows it.
For example, ping can be run with the -Q switch or iperf with the -S
switch. Separate applications such as softphones or video conferencing are able to mark their traffic on their own. You can also colorize traffic with the kernel using iptables.
But as a rule, server admins do not suffer from this, and marking has to be carried out already on network devices.

Answer 2

The information package is formed by the end system (computer). The generated packet contains the ToS field. Network equipment changes it or sets processing rules for packets with a certain ToS value.

Answer 3

These labels are set on the network equipment.

Answer 4

Network equipment, driving a packet through itself, exposes these tags. Some providers may reset them.