＝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