Protocol Data Units and OSI Model
Transport
defines services to segment, transfer, and reassemble the data for individual communications between the end devices, Port Addresses are encapsulated at this layer
Data-link
describe methods for exchanging data frames between devices over a common media, Physical Addresses are encapsulated at this layer
Physical
describe the mechanical, electrical, functional, and procedural means to activate, maintain, and de-activate physical connections for bit transmission to and from a network device
MAC
lower sublayer of the data-link layer defines the media access processes preformed by the hardware
Presentation
provides for common representation of the data transferred between Application layer services
Network
provides services to exchange individual pieces of data over the network between identified end devices, IP Addresses are encapsulated at this layer
Session
provides services to the Presentation layer to organize its dialogue and to manage data exchange
Application
provides the means for end-to-end connectivity between individuals in the human network using data networks
Frame
the data Link layer PDU
Data
the general term for PDUs used at the application layer
Packet
the network layer PDU
Bits
the physical layer PDU used when physically transmitting data over the medium
Segment
the transport layer PDU
LLC
upper sublayer of the data-link layer defines the software processes that provide services to the network layer protocols