Internet protocol suite - Wikipedia
With the advent of the World Wide Web The easiest way to understand computer networks is through the compare itself. The Internet is based on a 2- part networking system called TCP/IP in which computers hook up. The Internet works by using a protocol called TCP/IP, The Application Layer is utilized to ensure communication between applications on a network. The Internet is more like a series of tubes with various connection points. Each server or client on a TCP/IP internet is identified by a numeric IP address. there is not a one-to-one relationship between a host name and an IP address.
The last protocol is still in use today. The conference was founded by Dan Lynch, an early Internet activist.
Internet, HTTP and TCP/IP concepts
Key architectural principles[ edit ] Two Internet hosts connected via two routers and the corresponding layers used at each hop. The application on each host executes read and write operations as if the processes were directly connected to each other by some kind of data pipe.
Every other detail of the communication is hidden from each process. The underlying mechanisms that transmit data between the host computers are located in the lower protocol layers. Encapsulation of application data descending through the layers described in RFC The end-to-end principle has evolved over time.
Its original expression put the maintenance of state and overall intelligence at the edges, and assumed the Internet that connected the edges retained no state and concentrated on speed and simplicity. Real-world needs for firewalls, network address translators, web content caches and the like have forced changes in this principle. That is, it must be careful to send well-formed datagrams, but must accept any datagram that it can interpret e.
Encapsulation is usually aligned with the division of the protocol suite into layers of general functionality. In general, an application the highest level of the model uses a set of protocols to send its data down the layers, being further encapsulated at each level. It loosely defines a four-layer model, with the layers having names, not numbers, as follows: Application layer The application layer is the scope within which applications create user data and communicate this data to other applications on another or the same host.
The applications, or processes, make use of the services provided by the underlying, lower layers, especially the Transport Layer which provides reliable or unreliable pipes to other processes. The communications partners are characterized by the application architecture, such as the client-server model and peer-to-peer networking. Processes are addressed via ports which essentially represent services.
Transport layer The transport layer performs host-to-host communications on either the same or different hosts and on either the local network or remote networks separated by routers. UDP is the basic transport layer protocol, providing an unreliable datagram service. The Transmission Control Protocol provides flow-control, connection establishment, and reliable transmission of data.
Internet layer The internet layer exchanges datagrams across network boundaries. It provides a uniform networking interface that hides the actual topology layout of the underlying network connections.
It is therefore also referred to as the layer that establishes internetworking. Indeed, it defines and establishes the Internet. The primary protocol in this scope is the Internet Protocol, which defines IP addresses.
Its function in routing is to transport datagrams to the next IP router that has the connectivity to a network closer to the final data destination. Link layer The link layer defines the networking methods within the scope of the local network link on which hosts communicate without intervening routers. This layer includes the protocols used to describe the local network topology and the interfaces needed to effect transmission of Internet layer datagrams to next-neighbor hosts.
The layers of the protocol suite near the top are logically closer to the user application, while those near the bottom are logically closer to the physical transmission of the data.
Internet, HTTP and TCP/IP concepts
Viewing layers as providing or consuming a service is a method of abstraction to isolate upper layer protocols from the details of transmitting bits over, for example, Ethernet and collision detectionwhile the lower layers avoid having to know the details of each and every application and its protocol. Even when the layers are examined, the assorted architectural documents—there is no single architectural model such as ISOthe Open Systems Interconnection OSI model —have fewer and less rigidly defined layers than the OSI model, and thus provide an easier fit for real-world protocols.
One frequently referenced document, RFCdoes not contain a stack of layers. It only refers to the existence of the internetworking layer and generally to upper layers; this document was intended as a snapshot of the architecture: While this process of evolution is one of the main reasons for the technology's success, it nevertheless seems useful to record a snapshot of the current principles of the Internet architecture. This abstraction also allows upper layers to provide services that the lower layers do not provide.
This means that all transport layer implementations must choose whether or how to provide reliability. UDP provides data integrity via a checksum but does not guarantee delivery; TCP provides both data integrity and delivery guarantee by retransmitting until the receiver acknowledges the reception of the packet.
This model lacks the formalism of the OSI model and associated documents, but the IETF does not use a formal model and does not consider this a limitation, as illustrated in the comment by David D. Clark"We reject: For multi-access links with their own addressing systems e. Ethernet an address mapping protocol is needed.
Such protocols can be considered to be below IP but above the existing link system. Again, there was no intention, on the part of the designers of these protocols, to comply with OSI architecture. The link is treated as a black box. The IETF explicitly does not intend to discuss transmission systems, which is a less academic  [ citation needed ] but practical alternative to the OSI model.
Link layer[ edit ] The link layer has the networking scope of the local network connection to which a host is attached. The link layer is used to move packets between the Internet layer interfaces of two different hosts on the same link. The processes of transmitting and receiving packets on a given link can be controlled both in the software device driver for the network cardas well as on firmware or specialized chipsets.
These perform data link functions such as adding a packet header to prepare it for transmission, then actually transmit the frame over a physical medium.
All other aspects below that level, however, are implicitly assumed to exist in the link layer, but are not explicitly defined. This is also the layer where packets may be selected to be sent over a virtual private network or other networking tunnel. In this scenario, the link layer data may be considered application data which traverses another instantiation of the IP stack for transmission or reception over another IP connection.
Such a connection, or virtual link, may be established with a transport protocol or even an application scope protocol that serves as a tunnel in the link layer of the protocol stack. Internet layer[ edit ] The internet layer has the responsibility of sending packets across potentially multiple networks. Internetworking requires sending data from the source network to the destination network.
For additional information and insight, readers are urged to read two excellent histories of the Internet: In addition, the Internet Society maintains a number of on-line "Internet history" papers at http: In a series of memos dating back to AugustJ. Licklider of MIT discussed his "Galactic Network" and how social interactions could be enabled through networking. The Internet certainly provides such a national and global infrastructure and, in fact, interplanetary Internet communication has already been seriously discussed.
Prior to the s, what little computer communication existed comprised simple text and binary data, carried by the most common telecommunications network technology of the day; namely, circuit switching, the technology of the telephone networks for nearly a hundred years. Because most data traffic is bursty in nature i. The fundamental technology that makes the Internet work is called packet switching, a data network in which all components i.
In addition, network communication resources appear to be dedicated to individual users but, in fact, statistical multiplexing and an upper limit on the size of a transmitted entity result in fast, economical networks.
In the s, packet switching was ready to be discovered. InPaul Baran of the Rand Corporation described a robust, efficient, store-and-forward data network in a report for the U. The term packet was adopted from the work at NPL. The modern Internet began as a U. This "standard" interface encouraged BBN to start Telenet, a commercial packet-switched data service, in ; after much renaming, Telenet became a part of Sprint's X. Over time, however, NCP proved to be incapable of keeping up with the growing network traffic load.
But it seemed like overkill for the intermediate gateways what we would today call routers to needlessly have to deal with an end-to-end protocol so in a new design split responsibilities between a pair of protocols; the new Internet Protocol IP for routing packets and device-to-device communication i. The original versions of both TCP and IP that are in common use today were written in Septemberalthough both have had several modifications applied to them in addition, the IP version 6, or IPv6, specification was released in December This network, dubbed the NSFNET, was originally intended as a backbone for other networks, not as an interconnection mechanism for individual systems.
Migration to a "professionally-managed" network was supervised by a consortium comprising Merit a Michigan state regional network headquartered at the University of MichiganIBM, and MCI. During this period of time, the NSF also funded a number of regional Internet service providers ISPs to provide local connection points for educational institutions and NSF-funded sites. Inthe NSF decided that it did not want to be in the business of running and funding networks, but wanted instead to go back to the funding of research in the areas of supercomputing and high-speed communications.
In addition, there was increased pressure to commercialize the Internet; ina trial gateway connected MCI, CompuServe, and Internet mail services, and commercial users were now finding out about all of the capabilities of the Internet that once belonged exclusively to academic and hard-core users! Ina plan was put in place to reduce the NSF's role in the public Internet. The new structure was composed of three parts: This network was installed in and operated at OC-3 The Routing Arbiterto ensure adequate routing protocols for the Internet.
This funding ended by and a proliferation of additional NAPs have created a "melting pot" of services. New terminology started to refer to three tiers of ISP: A Tier 1 network refered to national ISPs, or those that have a national presence and connected to at least three of the original four NAPs. Today, a Tier 1 newtork refers to any network that can communicate with every other network via direct peering; i.
A Tier 2 network refers to regional ISPs, or those that have primarily a regional presence and connect to less than three of the original four NAPs. Today, a Tier 2 network refers to a provider that can reach every other network either directly or by purchasing upstream Internet services. It is worth saying a few words about the NAPs. The NSF provided major funding for the four NAPs mentioned above but they needed to have additional customers to remain economically viable.
Other companies also operate their own NAPs. Many large service providers go around the NAPs entirely by creating bilateral agreement whereby the directly route traffic coming from one network and going to the other; before their merger infor example, MCI and LDDS Worldcom had more than 10 DS-3 The North American Network Operators Group NANOG provides a forum for the exchange of technical information and the discussion of implementation issues that require coordination among network service providers.
Inmeanwhile, the DoD and most of the U. Government chose to adopt OSI protocols. We believe in rough consensus and running code" Dave Clark.
It was never the purpose of this memo to take a position on the OSI vs. As it was, many industry observers have pointed out that OSI represented the ultimate example of a sliding window; OSI protocols were "two years away" pretty consistently between the mids to mids. None of this is meant to suggest that the NSF isn't funding Internet-class research networks anymore. That is just the function of Internet2a consortium of nearly universities, corporations, and non-profit research oriented organizations working in partnership to develop and deploy advanced network applications and technologies for the next generation Internet.
Goals of Internet2 are to create a leading edge network capability for the national research community, enable the development of new Internet-based applications, and to quickly move these new network services and applications to the commercial sector. To paraphrase the hitchhiker, you may think that your node LAN is big, but that's just peanuts compared to the Internet. After that, the network experienced literally exponential growth. According to their chart, the Internet had nearly 30 million reachable hosts by January and just over a billion in July Dedicated residential access methods, such as cable modem and asymmetrical digital subscriber line ADSL technologies, are undoubtedly the reason that this number shot up during the decade and Internet of Things IoT devices will add more exponential growth into the s.
During the booms, the Internet was growing at a rate of about a new network attachment every half-hour, interconnecting hundreds of thousands of networks.
The Internet World Stats site is about the best to start learning about the demographics of the Internet. It grew smaller and smaller during the late s as sites and traffic moved to the Internet, and was decommissioned in July Internet Administration The Internet is a collection of autonomous, crash-independent networks.
The Internet has no single owner, yet everyone owns a portion of the Internet.
Comparison of OSI and TCP/IP Reference Model
The Internet has no central operator, yet everyone operates a portion of the Internet. The Internet has been compared to anarchy, but some claim that it is not nearly that well organized! Some central authority is required for the Internet, however, to manage those things that can only be managed centrally, such as addressing, naming, protocol development, standardization, etc.
Among the significant Internet authorities are: The Internet Society ISOCchartered inis a non-governmental international organization providing coordination for the Internet, and its internetworking technologies and applications.
The IETF's working groups have primary responsibility for the technical activities of the Internet, including writing specifications and protocols.