xué / xí / wǎng / luò / xié / yì / shí / xū / yào / lǐ / jiě / shù / jù / liàn / lù / céng / de / zuò / yòng

学习网络协议时，需要理解数据链路层的作用。

When studying network protocols, you need to understand the role of the data link layer.