You don’t have to have any large scale round-ups, in fact I doubt seriously this will happen. The media may try to create a fictional round-up, but there won’t be one.
Secure the border. Enforce the law. Let the chips fall. Once you stop the in-flow, over a very few years the problem resolves itself. Some people get caught up by Immigration, some people find some way to legalize themselves, some see there is no future here and they just go home. Without any mass deportation, the problem just goes away.
Its not that difficult, it only sounds difficult when its described by people with a vested interest in not doing it. Stop the inflow. Secure the border, enforce the law, and let nature take its course.
What I’ve been saying for years. The laws are already there. Enforcing the laws is all that’s required.