The OSI Model

Pneumonic Physical (Data cables, Cat6 for example) Data Link (MAC Addresses, Switching, Network (IP Addresses, Routing) Transport (TCP, UDP) Session (session management) Presentation (WMV, JPEG, MOV, Media) Application (HTTP, SMTP, FTP)

Please do not throw sausage pizza away When we say, my home router is a layer 2,3 It does both routing and switching When we receive data, it goes from layer 1 to 7 When we transmit data, it goes from layer 7 to 1 When we're troubleshooting, always start with the physical and go down