OSI layer

7 Application Layer HTTP/FTP/SMTP...

6 Presentation Layer The presentation layer prepares data for the application layer.

5 Session Layer The session layer creates communication channels, called sessions, between devices.

4 Transport Layer TCP / UDP .... The transport layer takes data transferred in the session layer and breaks it into “segments” on the transmitting end.

3 Network Layer Router, IP The network layer is responsible for packet forwarding including routing through intermediate routersThe network layer uses network addresses (typically Internet Protocol addresses) to route packets to a destination node.

2 Data Link Layer MAC, Switch... The data link layer is the protocol layer in a program that handles the moving of data into and out of a physical link in a network. The bridge between software and hardware.

1 Physical Layer Cable, Hub... The physical layer is responsible for the physical cable or wireless connection between network nodes.

TCP 3-Way Handshake

1. SYN
2. SYN+ACK
3. ACK

Load Balancer layer4/layer7