Encapsulation (networking)
Encyclopedia
Computer network
A computer network, often simply referred to as a network, is a collection of hardware components and computers interconnected by communication channels that allow sharing of resources and information....
ing, encapsulation is a method of designing modular communication protocols in which logically separate functions in the network are abstracted
Abstraction (computer science)
In computer science, abstraction is the process by which data and programs are defined with a representation similar to its pictorial meaning as rooted in the more complex realm of human life and language with their higher need of summarization and categorization , while hiding away the...
from their underlying structures by inclusion or information hiding
Information hiding
In computer science, information hiding is the principle of segregation of the design decisions in a computer program that are most likely to change, thus protecting other parts of the program from extensive modification if the design decision is changed...
within higher level objects.
The physical layer is responsible for physical transmission of the data. Link encapsulation allows local area networking and IP provides global addressing of individual computers; UDP adds application or process selection, i.e., the port
TCP and UDP port
In computer networking, a port is an application-specific or process-specific software construct serving as a communications endpoint in a computer's host operating system. A port is associated with an IP address of the host, as well as the type of protocol used for communication...
specifies the service such as a Web
Web server
Web server can refer to either the hardware or the software that helps to deliver content that can be accessed through the Internet....
or TFTP
Trivial File Transfer Protocol
Trivial File Transfer Protocol is a file transfer protocol known for its simplicity. It is generally used forautomated transfer of configuration or boot files between machines in a local environment....
server.
In discussions of encapsulation, the more abstract layer is often called the upper layer protocol
Upper layer protocol
In computer networking, the term upper layer protocol refers to a more abstract protocol when performing encapsulation, in particular it is often used to describe the protocols above the network layer....
while the more specific layer is called the lower layer protocol
Lower layer protocol
In computer networking, the term lower layer protocol refers to a more specific protocol when performing encapsulation.In discussions of the Internet Protocol Suite, lower layer protocols are usually considered to be protocols below the IP level, i.e. the protocols in the Link Layer.The term...
. Sometimes, however, the terms upper layer protocol
Upper layer protocol
In computer networking, the term upper layer protocol refers to a more abstract protocol when performing encapsulation, in particular it is often used to describe the protocols above the network layer....
s and lower layer protocol
Lower layer protocol
In computer networking, the term lower layer protocol refers to a more specific protocol when performing encapsulation.In discussions of the Internet Protocol Suite, lower layer protocols are usually considered to be protocols below the IP level, i.e. the protocols in the Link Layer.The term...
s are used to describe the layers above and below IP, respectively.
Encapsulation is a characteristic feature of most networking models, including the OSI Model
OSI model
The Open Systems Interconnection model is a product of the Open Systems Interconnection effort at the International Organization for Standardization. It is a prescription of characterizing and standardizing the functions of a communications system in terms of abstraction layers. Similar...
and TCP/IP suite of protocols.