Link Layer 5. 1 Introduction and o5.6 Hubs and switches services o5.7PPP o 5.2 Error detection and correction 6 5.3 Multiple access protocols o 5.4 Link-Layer Addressing o5.5 Ethernet 5: DatLink Layer  5.1 Introduction and services  5.2 Error detection and correction  5.3 Multiple access protocols  5.4 Link-Layer Addressing  5.5 Ethernet  5.6 Hubs and switches  5.7 PPP 5: DataLink Layer 5-2