Abstraction layer in the context of "Internet protocol suite"

A network address is an identifier for a node or host on a telecommunications network. Network addresses are designed to be unique identifiers across the network, although some networks allow for local, private addresses, or locally administered addresses that may not be unique. Special network addresses are allocated as broadcast or multicast addresses. These too are not unique.

In some cases, network hosts may have more than one network address. For example, each network interface controller may be uniquely identified. Further, because protocols are frequently layered, more than one protocol's network address can occur in any particular network interface or node and more than one type of network address may be used in any one network.

The protocol stack or network stack is an implementation of a computer networking protocol suite or protocol family. Some of these terms are used interchangeably but strictly speaking, the suite is the definition of the communication protocols, and the stack is the software implementation of them.

Individual protocols within a suite are often designed with a single purpose in mind. This modularization simplifies design and evaluation. Because each protocol module usually communicates with two others, they are commonly imagined as layers in a stack of protocols. The lowest protocol always deals with low-level interaction with the communications hardware. Each higher layer adds additional capabilities. User applications usually deal only with the topmost layers.

In computer networking, the link layer is the lowest layer in the Internet protocol suite, the networking architecture of the Internet. The link layer is the group of methods and communications protocols confined to the link that a host is physically connected to. The link is the physical and logical network component used to interconnect hosts or nodes in the network, and a link protocol is a suite of methods and standards that operate only between adjacent network nodes of a network segment.

Despite the different semantics of layering between the Internet protocol suite and OSI model, the link layer is sometimes described as a combination of the OSI's data link layer (layer 2) and physical layer (layer 1).

In computer networking, the transport layer is a conceptual division of methods in the layered architecture of protocols in the network stack in the Internet protocol suite and the OSI model. The protocols of this layer provide end-to-end communication services for applications. It provides services such as connection-oriented communication, reliability, flow control, and multiplexing.

The details of implementation and semantics of the transport layer of the Internet protocol suite,, which is the foundation of the Internet, and the OSI model of general networking are different. The protocols in use today in this layer for the Internet all originated in the development of TCP/IP. In the OSI model, the transport layer is often referred to as Layer 4, or L4, while numbered layers are not used in TCP/IP.

An application layer is an abstraction layer that specifies the shared communication protocols and interface methods used by hosts in a communications network. An application layer abstraction is specified in both the Internet Protocol Suite (TCP/IP) and the OSI model. Although both models use the same term for their respective highest-level layer, the detailed definitions and purposes are different.

The Open Systems Interconnection (OSI) model is a reference model developed by the International Organization for Standardization (ISO) that "provides a common basis for the coordination of standards development for the purpose of systems interconnection."

In the OSI reference model, the components of a communication system are distinguished in seven abstraction layers: Physical, Data Link, Network, Transport, Session, Presentation, and Application.

A content delivery network (CDN) or content distribution network is a geographically distributed network of proxy servers and corresponding data centers. CDNs provide high availability and performance ("speed") through geographical distribution relative to end users, and arose in the late 1990s to alleviate the performance bottlenecks of the Internet as it was becoming a critical medium. Since then, CDNs have grown to serve a large portion of Internet content, including text, graphics and scripts, downloadable objects (media files, software, and documents), applications (e-commerce, portals), live streaming media, on-demand streaming media, and social media services.

CDNs are a layer in the internet ecosystem. Content owners such as media companies and e-commerce vendors pay CDN operators to deliver their content to their end users. In turn, a CDN pays Internet service providers (ISPs), carriers, and network operators for hosting its servers in their data centers.