=OSI Model and Transmission Path=
 A.OSI 7-Layer Model
 B.Signals and Network Media
 C.Data Link Layer
 D.Bridges and Repeaters
 E.ARP and ARP tables
 F.Topologies and Access Methods
  Related Items
 C-1 Roles of the data link layer
 C-2 Two sublayers of the data link layer
 C-3 Standards for the data link layer
 ・ Exercise