Application: interfaces to access the network (DHCP, HTTP, FTP, etc)
– PDU = data

Presentation: presents the data (either generic in format / reassembles for delivery to App layer)
– PDU = data

Session: Establishes session before data sent (kinda a 3 way handshake).
– does Checkpoints and Synchronization
– authentication protocols
– PDU = data

Transport Layer
– PDU = segment
– TCP ensures reliable delivery – connection oriented
– MTU (maximum transmission unit) 1518 bytes for ethernet
– Flow control and sequencing
– Source and destination Port numbers

Network Layer
– PDU = packet
– IP address – connectionless
– Access control – routing process
– routers / layer 3 switch

Data Link
– PDU = frame
– MAC addresses  Source and Destination
– Media Access Control
– FCS frame check sequence (form of CRC error handling) – recalculated between routers
– NIC driver – software aspect
– Switches

Physical

– PDU = bits and bytes
– encoding / deencoding
– MTU (maximum transmission unit) 1518bytes for ethernet
– Flow control and sequencing
– Source and destination Port numbers

IN ADDITION, you should know the proper breakdown for the TCP/IP Model