In the TCP/IP-based layered network, layer 2 is the data link layer. This layer is also called simply the link layer. The actual protocols encompassed in the link layer are numerous, and the implementation details can be found in various documents throughout the Internet and in trade texts. For the purpose of this discussion, we'll limit the scope to aspects of the link layer that a network administrator would need to know. The foremost data link layer protocol is the Ethernet protocol.