What is the mangle rule for in Mikrotik?

Question

VPN

I set up the l2tp client without the mangle, but in the manual with it.
I don't understand what and why?

Answer 1

Package labeling. With the help of which, in further configuration, you can direct only certain traffic through the l2tp tunnel. For example, launch a website or an application.

Answer 2

I highly recommend the old iptables manual

Answer 3

For selective labeling of packages. In order not to write a bundle of the same type of rules in the filter later, but to make everything one.