Key to making the packet radio system work was a reliable end-end protocol that could maintain effective communication in the face of jamming and other radio interference, or withstand intermittent blackout such as caused by being in a tunnel or blocked by the local terrain. Kahn first contemplated developing a protocol local only to the packet radio network, since that would avoid having to deal with the multitude of different operating systems, and continuing to use NCP. If any packets were lost, the protocol and presumably any applications it supported would come to a grinding halt.
In this model NCP had no end-end host error control, since the ARPANET was to be the only network in existence and it would be so reliable that no error control would be required on the part of the hosts. Thus, Kahn decided to develop a new version of the protocol which could meet the needs of an open-architecture network environment.
While NCP tended to act like a device driver, the new protocol would be more like a communications protocol. At this point he realized it would be necessary to learn the implementation details of each operating system to have a chance to embed any new protocols in an efficient way. Thus, in the spring of , after starting the internetting effort, he asked Vint Cerf then at Stanford to work with him on the detailed design of the protocol. Cerf had been intimately involved in the original NCP design and development and already had the knowledge about interfacing to existing operating systems.
The give and take was highly productive and the first written version 7 of the resulting approach was distributed at a special meeting of the International Network Working Group INWG which had been set up at a conference at Sussex University in September Cerf had been invited to chair this group and used the occasion to hold a meeting of INWG members who were heavily represented at the Sussex Conference. Kahn had intended that the TCP protocol support a range of transport services, from the totally reliable sequenced delivery of data virtual circuit model to a datagram service in which the application made direct use of the underlying network service, which might imply occasional lost, corrupted or reordered packets.
However, the initial effort to implement TCP resulted in a version that only allowed for virtual circuits. This model worked fine for file transfer and remote login applications, but some of the early work on advanced network applications, in particular packet voice in the s, made clear that in some cases packet losses should not be corrected by TCP, but should be left to the application to deal with.
This led to a reorganization of the original TCP into two protocols, the simple IP which provided only for addressing and forwarding of individual packets, and the separate TCP, which was concerned with service features such as flow control and recovery from lost packets.
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Connecting the two together was far more economical that duplicating these very expensive computers. However, while file transfer and remote login Telnet were very important applications, electronic mail has probably had the most significant impact of the innovations from that era. Email provided a new model of how people could communicate with each other, and changed the nature of collaboration, first in the building of the Internet itself as is discussed below and later for much of society.
A key concept of the Internet is that it was not designed for just one application, but as a general infrastructure on which new applications could be conceived, as illustrated later by the emergence of the World Wide Web. The Stanford team, led by Cerf, produced the detailed specification and within about a year there were three independent implementations of TCP that could interoperate. This was the beginning of long term experimentation and development to evolve and mature the Internet concepts and technology.
Beginning with the first three networks ARPANET, Packet Radio, and Packet Satellite and their initial research communities, the experimental environment has grown to incorporate essentially every form of network and a very broad-based research and development community. When desktop computers first appeared, it was thought by some that TCP was too big and complex to run on a personal computer. That implementation was fully interoperable with other TCPs, but was tailored to the application suite and performance objectives of the personal computer, and showed that workstations, as well as large time-sharing systems, could be a part of the Internet.
It included an emphasis on the complexity of protocols and the pitfalls they often introduce. This book was influential in spreading the lore of packet switching networks to a very wide community. This change from having a few networks with a modest number of time-shared hosts the original ARPANET model to having many networks has resulted in a number of new concepts and changes to the underlying technology. First, it resulted in the definition of three network classes A, B, and C to accommodate the range of networks. Class A represented large national scale networks small number of networks with large numbers of hosts ; Class B represented regional scale networks; and Class C represented local area networks large number of networks with relatively few hosts.
A major shift occurred as a result of the increase in scale of the Internet and its associated management issues. To make it easy for people to use the network, hosts were assigned names, so that it was not necessary to remember the numeric addresses. Originally, there were a fairly limited number of hosts, so it was feasible to maintain a single table of all the hosts and their associated names and addresses. The shift to having a large number of independently managed networks e. The DNS permitted a scalable distributed mechanism for resolving hierarchical host names e.
The increase in the size of the Internet also challenged the capabilities of the routers. Originally, there was a single distributed algorithm for routing that was implemented uniformly by all the routers in the Internet. As the number of networks in the Internet exploded, this initial design could not expand as necessary, so it was replaced by a hierarchical model of routing, with an Interior Gateway Protocol IGP used inside each region of the Internet, and an Exterior Gateway Protocol EGP used to tie the regions together.
This design permitted different regions to use a different IGP, so that different requirements for cost, rapid reconfiguration, robustness and scale could be accommodated. Not only the routing algorithm, but the size of the addressing tables, stressed the capacity of the routers. New approaches for address aggregation, in particular classless inter-domain routing CIDR , have recently been introduced to control the size of router tables.
As the Internet evolved, one of the major challenges was how to propagate the changes to the software, particularly the host software. Looking back, the strategy of incorporating Internet protocols into a supported operating system for the research community was one of the key elements in the successful widespread adoption of the Internet.
This enabled defense to begin sharing in the DARPA Internet technology base and led directly to the eventual partitioning of the military and non- military communities. Thus, by , Internet was already well established as a technology supporting a broad community of researchers and developers, and was beginning to be used by other communities for daily computer communications. Electronic mail was being used broadly across several communities, often with different systems, but interconnection between different mail systems was demonstrating the utility of broad based electronic communications between people.
At the same time that the Internet technology was being experimentally validated and widely used amongst a subset of computer science researchers, other networks and networking technologies were being pursued. The usefulness of computer networking — especially electronic mail — demonstrated by DARPA and Department of Defense contractors on the ARPANET was not lost on other communities and disciplines, so that by the mids computer networks had begun to spring up wherever funding could be found for the purpose.
The U. NSFNET programs to explicitly announce their intent to serve the entire higher education community, regardless of discipline. Indeed, a condition for a U. When Steve Wolff took over the NSFNET program in , he recognized the need for a wide area networking infrastructure to support the general academic and research community, along with the need to develop a strategy for establishing such infrastructure on a basis ultimately independent of direct federal funding.
Policies and strategies were adopted see below to achieve that end. It had seen the Internet grow to over 50, networks on all seven continents and outer space, with approximately 29, networks in the United States.
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A key to the rapid growth of the Internet has been the free and open access to the basic documents, especially the specifications of the protocols. The beginnings of the ARPANET and the Internet in the university research community promoted the academic tradition of open publication of ideas and results.
However, the normal cycle of traditional academic publication was too formal and too slow for the dynamic exchange of ideas essential to creating networks. In a key step was taken by S. These memos were intended to be an informal fast distribution way to share ideas with other network researchers.
At first the RFCs were printed on paper and distributed via snail mail. Jon Postel acted as RFC Editor as well as managing the centralized administration of required protocol number assignments, roles that he continued to play until his death, October 16, When some consensus or a least a consistent set of ideas had come together a specification document would be prepared.
Such a specification would then be used as the base for implementations by the various research teams. The open access to the RFCs for free, if you have any kind of a connection to the Internet promotes the growth of the Internet because it allows the actual specifications to be used for examples in college classes and by entrepreneurs developing new systems. Email has been a significant factor in all areas of the Internet, and that is certainly true in the development of protocol specifications, technical standards, and Internet engineering.
The very early RFCs often presented a set of ideas developed by the researchers at one location to the rest of the community. After email came into use, the authorship pattern changed — RFCs were presented by joint authors with common view independent of their locations. The use of specialized email mailing lists has been long used in the development of protocol specifications, and continues to be an important tool. The IETF now has in excess of 75 working groups, each working on a different aspect of Internet engineering.
Each of these working groups has a mailing list to discuss one or more draft documents under development. When consensus is reached on a draft document it may be distributed as an RFC. This unique method for evolving new capabilities in the network will continue to be critical to future evolution of the Internet. The Internet is as much a collection of communities as a collection of technologies, and its success is largely attributable to both satisfying basic community needs as well as utilizing the community in an effective way to push the infrastructure forward.
The early ARPANET researchers worked as a close-knit community to accomplish the initial demonstrations of packet switching technology described earlier. Likewise, the Packet Satellite, Packet Radio and several other DARPA computer science research programs were multi-contractor collaborative activities that heavily used whatever available mechanisms there were to coordinate their efforts, starting with electronic mail and adding file sharing, remote access, and eventually World Wide Web capabilities.
In the late s, recognizing that the growth of the Internet was accompanied by a growth in the size of the interested research community and therefore an increased need for coordination mechanisms, Vint Cerf, then manager of the Internet Program at DARPA, formed several coordination bodies — an International Cooperation Board ICB , chaired by Peter Kirstein of UCL, to coordinate activities with some cooperating European countries centered on Packet Satellite research, an Internet Research Group which was an inclusive group providing an environment for general exchange of information, and an Internet Configuration Control Board ICCB , chaired by Clark.
In , when Barry Leiner took over management of the Internet research program at DARPA, he and Clark recognized that the continuing growth of the Internet community demanded a restructuring of the coordination mechanisms. The ICCB was disbanded and in its place a structure of Task Forces was formed, each focused on a particular area of the technology e. It of course was only a coincidence that the chairs of the Task Forces were the same people as the members of the old ICCB, and Dave Clark continued to act as chair.
This growth was complemented by a major expansion in the community. In addition to NSFNet and the various US and international government-funded activities, interest in the commercial sector was beginning to grow. As a result, the IAB was left without a primary sponsor and increasingly assumed the mantle of leadership. The growth in the commercial sector brought with it increased concern regarding the standards process itself. Increased attention was paid to making the process open and fair. In , yet another reorganization took place. In , the Internet Activities Board was re-organized and re-named the Internet Architecture Board operating under the auspices of the Internet Society.
The recent development and widespread deployment of the World Wide Web has brought with it a new community, as many of the people working on the WWW have not thought of themselves as primarily network researchers and developers. Thus, through the over two decades of Internet activity, we have seen a steady evolution of organizational structures designed to support and facilitate an ever-increasing community working collaboratively on Internet issues.
Commercialization of the Internet involved not only the development of competitive, private network services, but also the development of commercial products implementing the Internet technology. Unfortunately they lacked both real information about how the technology was supposed to work and how the customers planned on using this approach to networking. The speakers came mostly from the DARPA research community who had both developed these protocols and used them in day-to-day work. About vendor personnel came to listen to 50 inventors and experimenters.
The results were surprises on both sides: the vendors were amazed to find that the inventors were so open about the way things worked and what still did not work and the inventors were pleased to listen to new problems they had not considered, but were being discovered by the vendors in the field.
Thus a two-way discussion was formed that has lasted for over a decade. In September of the first Interop trade show was born. It did. The Interop trade show has grown immensely since then and today it is held in 7 locations around the world each year to an audience of over , people who come to learn which products work with each other in a seamless manner, learn about the latest products, and discuss the latest technology. Starting with a few hundred attendees mostly from academia and paid for by the government, these meetings now often exceed a thousand attendees, mostly from the vendor community and paid for by the attendees themselves.
The reason it is so useful is that it is composed of all stakeholders: researchers, end users and vendors. Network management provides an example of the interplay between the research and commercial communities. In the beginning of the Internet, the emphasis was on defining and implementing protocols that achieved interoperation.
As the network grew larger, it became clear that the sometime ad hoc procedures used to manage the network would not scale. Manual configuration of tables was replaced by distributed automated algorithms, and better tools were devised to isolate faults. In it became clear that a protocol was needed that would permit the elements of the network, such as the routers, to be remotely managed in a uniform way. The market could choose the one it found more suitable.
SNMP is now used almost universally for network-based management. In the last few years, we have seen a new phase of commercialization. Originally, commercial efforts mainly comprised vendors providing the basic networking products, and service providers offering the connectivity and basic Internet services.
This has been tremendously accelerated by the widespread and rapid adoption of browsers and the World Wide Web technology, allowing users easy access to information linked throughout the globe. Products are available to facilitate the provisioning of that information and many of the latest developments in technology have been aimed at providing increasingly sophisticated information services on top of the basic Internet data communications. Environment portal Renewable energy portal Social movements portal.
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