Content-centric Networking
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Content-Centric Networking (CCN) diverges from the IP-based, host-oriented
Internet The Internet (or internet) is the Global network, global system of interconnected computer networks that uses the Internet protocol suite (TCP/IP) to communicate between networks and devices. It is a internetworking, network of networks ...
architecture by prioritizing content, making it directly addressable and routable. In CCN, endpoints communicate based on named data rather than
IP addresses An Internet Protocol address (IP address) is a numerical label such as that is assigned to a device connected to a computer network that uses the Internet Protocol for communication. IP addresses serve two main functions: network interface id ...
. This approach is a part of information-centric networking (ICN) architecture and involves the exchange of content request messages (termed "Interests") and content return messages (termed "Content Objects"). In this paradigm, connectivity may well be intermittent, end-host and in-network storage can be capitalized upon transparently, as bits in the network and on data storage devices have exactly the same value, mobility and multi access are the norm and
anycast Anycast is a network addressing and routing methodology in which a single IP address is shared by devices (generally servers) in multiple locations. Routers direct packets addressed to this destination to the location nearest the sender, using ...
,
multicast In computer networking, multicast is a type of group communication where data transmission is addressed to a group of destination computers simultaneously. Multicast can be one-to-many or many-to-many distribution. Multicast differs from ph ...
, and broadcast are natively supported. Data becomes independent from location, application, storage, and means of transportation, enabling in-network caching and replication. The expected benefits are improved efficiency, better scalability with respect to information/bandwidth demand and better robustness in challenging communication scenarios. In information-centric networking the cache is a network level solution, and it has rapidly changing cache states, higher request arrival rates and smaller cache sizes. In particular,
information-centric networking caching policies In computing, cache algorithms (also frequently called cache replacement algorithms or cache replacement policies) are optimizing instructionsor algorithmsthat a computer program or a hardware-maintained structure can follow in order to manage ...
should be fast and lightweight.


History

The principles behind information-centric networks were first described in the original 17 rules of
Ted Nelson Theodor Holm Nelson (born June 17, 1937) is an American pioneer of information technology, philosopher, and sociologist. He coined the terms ''hypertext'' and ''hypermedia'' in 1963 and published them in 1965. According to his 1997 ''Forbes'' p ...
's
Project Xanadu Project Xanadu ( ) was the first hypertext project, founded in 1960 by Ted Nelson. Administrators of Project Xanadu have declared it superior to the World Wide Web, with the mission statement: "Today's popular software simulates paper. The World ...
in 1979. In 2002, Brent Baccala submitted an
Internet-Draft An Internet Draft (I-D) is a document published by the Internet Engineering Task Force (IETF) containing preliminary technical specifications, results of computer network, networking-related research, or other technical information. Often, Intern ...
differentiating between connection-oriented and data-oriented networking and suggested that the Internet web architecture was rapidly becoming more data-oriented. In 2006, the DONA project at UC Berkeley and ICSI proposed an information-centric network architecture, which improved TRIAD by incorporating security (authenticity) and persistence as first-class primitives in the architecture. On August 30, 2006, PARC Research Fellow
Van Jacobson Van Jacobson is an American computer scientist, renowned for his work on TCP/IP network performance and scaling.Project CCNx website
on September 21, 2009. The original CCN design was described in a paper published at the International Conference on Emerging Networking EXperiments and Technologies (CoNEXT) in December 2009. Annual CCNx Community meetings were held in 2011, 2012, 2013 and 2015. Th
protocol specification
for CCNx 1.0 has been made available for comment and discussion. Work on CCNx happens openly in th
ICNRG
IRTF research group.


Specification

The CCNx specification was published in some
IETF The Internet Engineering Task Force (IETF) is a standards organization for the Internet standard, Internet and is responsible for the technical standards that make up the Internet protocol suite (TCP/IP). It has no formal membership roster ...
drafts. The specifications included:
draft-irtf-icnrg-ccnxsemantics-01

draft-irtf-icnrg-ccnxmessages-01

draft-mosko-icnrg-ccnxurischeme-00
Seamless data integration within an open-run environment was proposed as a major contributing factor in protecting the security of cloud-based analytics and key network encryption. The driving force in adopting these heuristics was twofold: Batch-interrupted data streams remaining confined to an optimal run environment, and secure shared cloud access depending upon integrative analytic processes.


Software

The CCNx software was available on
GitHub GitHub () is a Proprietary software, proprietary developer platform that allows developers to create, store, manage, and share their code. It uses Git to provide distributed version control and GitHub itself provides access control, bug trackin ...
.


Motivation and benefits

The functional goal of the Internet Protocol as conceived and created in the 1970s was to enable two machines, one comprising resources and the other desiring access to those resources, to have a conversation with each other. The operating principle was to assign addresses to endpoints, thereby enabling these endpoints to locate and connect with one another. Since those early days, there have been fundamental changes in the way the Internet is used — from the proliferation of social networking services to viewing and sharing digital content such as videos, photographs, documents, etc. Instead of providing basic connectivity, the Internet has become largely a distribution network with massive amounts of video and web page content flowing from content providers to viewers. Increasingly, today's internet users demand faster, more efficient, and more secure access to content without concern about where that content might be located. Networks are also used in many environments where the traditional TCP/IP communication model doesn't fit. The Internet of Things (IoT) and sensor networks are environments where the source-destination communication model doesn't always provide the best solution. CCN was designed to work in many environments from high-speed data centers to resource-constrained sensors. CCN aims to be: * Secure - The CCN communication model secures data and not the communication pipe between two specific end hosts. However, ubiquitous content caching and the absence of a secure communication pipe between end hosts introduce the challenge to content protection against unauthorized access, which requires extra care and solutions. * Flexible - CCN uses names to communicate. Names can be location-independent and are much more adaptable than IP addresses. Network elements can make more advanced choices based on the named requests and data. * Scalable - CCN enables the network to scale by allowing caching, enabling native multicast traffic, providing native load balancing, and facilitating resource planning.


Basic concepts

Content Object messages are named payloads that are network-sized chunks of data. Names are a hierarchical series of binary name segments that are assigned to Content Objects by content publishers. Signatures are cryptographic bindings between a name, a payload, and the Key ID of the publisher. This is used for provenance. Interest messages are requests for Content Objects that match the name along with some optional restrictions on that object. The core protocol operates as follows: Consumers request content by sending an Interest message with the name of the desired content. The network routes the interest based on the name using
longest prefix match Longest prefix match (also called Maximum prefix length match) refers to an algorithm used by routers in Internet Protocol (IP) networking to select an entry from a routing table. Because each entry in a forwarding table may specify a sub-netwo ...
. The interest leaves the state as it traverses the network. This state is stored in the Pending Interest Table (PIT). When a match is found (when an Interest matches a Content Object) the content is sent back on the reverse path of the Interest, following the PIT state created by the Interest. Because the content is self-identifiable (via the name and the security binding) any Content Object can be cached. Interest messages may be matched against caches along the way, not only at the publishers. Distributed caching within a content-centric network is also possible, requiring multi-functional access parameters across the database. This essentially enables shared network encryption algorithms to employ role-based access limitations to users based on defined authorization levels.


CCNx releases


CCNx 0.x

Interests match Content Objects based on name prefixes. For example, an Interest for /a/b would match a Content Object named /a/b/c/d or /a/b. Interests include restrictions in the form of selectors. These help the network select which of the possible prefix matches are actual matches. For example, an Interest might exclude certain names, ask for a minimum or a maximum number of extra name segments, etc. Content Objects have an implicit final name component that is equal to the hash of the Content Object. This may be used for matching to a name. Packet encoding is done using CCNB (a proprietary format based on a type of binary XML). The last version of this branch is 0.8.2 Software i
available
under a GPL license
Specifications and documentation
are also available.


CCNx 1.x

CCNx 1.x differs from CCNx 0.x in the following ways:Solis, Ignacio (July 2014)
"CCNx 1.0 Changes from 0.x"
IETF-90 Proceedings. Toronto, Ontario. Retrieved 1 August 2014.
Interests match Content Objects on exact names, not name prefixes. Therefore, an Interest for /a/b/ will only match a Content Object with the name /a/b. Interests can restrict matches on the publisher KeyID or the object's ContentObjectHash. A nested
type–length–value Within communication protocols, TLV (type-length-value or tag-length-value) is an encoding scheme used for informational elements. A TLV-encoded data stream contains code related to the record type, the record value's length, and finally the valu ...
(TLV) format is used to encode all messages on the wire. Each message is composed of a set of packet headers and a protocol message that includes the name, the content (or
payload Payload is the object or the entity that is being carried by an aircraft or launch vehicle. Sometimes payload also refers to the carrying capacity of an aircraft or launch vehicle, usually measured in terms of weight. Depending on the nature of t ...
), and information used to cryptographically validate the message – all contained in nested TLVs. The specification of CCNx 1.0 is available at: http://blogs.parc.com/ccnx/specifications/


Derivative works

*
Named data networking Named Data Networking (NDN) (related to content-centric networking (CCN), content-based networking, data-oriented networking or information-centric networking (ICN)) is a proposed Future Internet architecture that seeks to address problems in conte ...
is an NSF-funded project based on the original CCNx 0.x code.
CCN-lite
is a lightweight version of CCNx functionally interoperable with CCN 0.x. *


See also

*
Information-centric networking Information-centric networking (ICN) is an approach to evolve the Internet infrastructure away from a host-centric paradigm, based on perpetual connectivity and the end-to-end principle, to a network architecture in which the focal point is identif ...
*
Named data networking Named Data Networking (NDN) (related to content-centric networking (CCN), content-based networking, data-oriented networking or information-centric networking (ICN)) is a proposed Future Internet architecture that seeks to address problems in conte ...
*
Information-centric networking caching policies In computing, cache algorithms (also frequently called cache replacement algorithms or cache replacement policies) are optimizing instructionsor algorithmsthat a computer program or a hardware-maintained structure can follow in order to manage ...


References

{{Reflist, 2 Computer networking