フリー問題

問題文

What does priority flow control do when a receiving port is running out of buffer for one class of traffic?

選択肢

1. It stops all transmission on the link until the buffer is empty, which is why it must be enabled on only one link per path, so a single congested class idles every other class too.
2. It asks the upstream sender to stop transmitting that one priority for a period, while the other priorities on the same link keep flowing.
3. It marks the frames of that class so the receiving endpoint can count them and report the condition to a management system, which then decides whether to reduce the sending rate on behalf of the application.
4. It drops the frames of that class immediately so that the sender detects the loss and slows down on its own.