modular design A design that calls for the complete system to be built from individual components that pass information across well-defined interfaces.
Network Access layer The layer of the TCP/IP stack that provides an interface with the physical network.
Internet layer The layer of the TCP/IP stack that provides logical addressing and routing.
Transport layer The layer of the TCP/IP stack that provides error control and acknowledgment and serves as an interface for network applications.
Application layer The layer of the TCP/IP stack that supports network applications and provides an interface to the local operating environment.
header A bundle of protocol information attached to the data at each layer of the protocol stack.
message In TCP/IP networking, a message is the data package passed from the Application layer to the Transport layer. The term is also used generically to describe a message from one entity to another on the network. The term doesn't always refer to an Application layer data package.
segment The data package passed from TCP at the Transport layer to the Internet layer.
datagram The data package passed from the Internet layer to the Network Access layer, or a data package passed from UDP at the Transport layer to the Internet layer.
frame The data package created at the Network Access layer according to the specification of the physical network.
TCP (Transmission Control Protocol) A Transport layer, reliable, connection-oriented protocol.
UDP (User Datagram Protocol) A Transport layer, nonreliable, connectionless protocol.
IP (Internet Protocol) The Internet layer protocol that provides logical addressing and routing capabilities.
