And that is the last packet sent in the clear.

Only the first packet sent from each end should have this flag set.

We're able to send packets off, and they get to where we aim them.

It will send packets that are intended for somebody else to the bad guy.

Sometimes two cards talk (send packets) at the same time.

The host should then send packets for the destination directly to R2.

For example, computers are able to send packets ahead of time, and the Internet only acknowledges them.

So packets sent later could arrive sooner at the receiving end.

There you're sending packets only when you need to.

This results in packets being sent in both directions at the same time.