| RFC 8793 | ICN Terminology | June 2020 |
| Wissingh, et al. | Informational | [Page] |
Information-Centric Networking (ICN) is a novel paradigm where network communications are accomplished by requesting named content instead of sending packets to destination addresses. Named Data Networking (NDN) and Content-Centric Networking (CCNx) are two prominent ICN architectures. This document provides an overview of the terminology and definitions that have been used in describing concepts in these two implementations of ICN. While there are other ICN architectures, they are not part of the NDN and CCNx concepts and as such are out of scope for this document. This document is a product of the Information-Centric Networking Research Group (ICNRG).¶
This document is not an Internet Standards Track specification; it is published for informational purposes.¶
This document is a product of the Internet Research Task Force (IRTF). The IRTF publishes the results of Internet-related research and development activities. These results might not be suitable for deployment. This RFC represents the consensus of the Information-Centric Networking Research Group of the Internet Research Task Force (IRTF). Documents approved for publication by the IRSG are not a candidate for any level of Internet Standard; see Section 2 of RFC 7841.¶
Information about the current status of this document, any errata, and how to provide feedback on it may be obtained at https://www.rfc-editor.org/info/rfc8793.¶
Copyright (c) 2020 IETF Trust and the persons identified as the document authors. All rights reserved.¶
This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents (https://trustee.ietf.org/license-info) in effect on the date of publication of this document. Please review these documents carefully, as they describe your rights and restrictions with respect to this document.¶
Information-centric networking (ICN) is an architecture to evolve the Internet infrastructure from the existing host-centric design to a data-centric architecture, where accessing data by name becomes the essential network primitive. The goal is to let applications refer to data independently of their location or means of transportation, which enables native multicast delivery, ubiquitous in-network caching, and replication of data objects.¶
As the work on this topic continues to evolve, many new terms are emerging. The goal of this document is to collect the key terms with a corresponding definition as they are used in the CCNx and NDN projects. Among the important documents for these projects are [RFC8569], [RFC8609], and [NDNTLV]. Other ICN projects such as [NETINF], [PSIRP], or [MOBILITY-FIRST] are not covered and may be the subject of other documents.¶
In this document, to help provide context for the individual defined terms, we first sketch the bigger picture of an ICN network by introducing the basic concepts and identifying the major components of the architecture in Section 2; after which, in Section 3, ICN-related terms are listed by different categories. Readers should be aware that in this organization, some terms may be used in other definitions before they themselves are defined.¶
While this terminology document describes both confidentiality and integrity-related terms, it should be noted that ICN architectures like NDN and CCNx generally do not provide data confidentiality, which is treated in these architectures as an application-layer concern.¶
This document represents the consensus of the Information-Centric Networking Research Group (ICNRG). It has been reviewed extensively by the Research Group (RG) members active in the specific areas of work covered by the document. It is not an IETF product and is not intended for standardization in the IETF.¶
In networking terms, an ICN is a delivery infrastructure for named data. For other complementing views, see Section 4.¶
requestor zero or more data sources or
(node) forwarding nodes replica nodes
| | ... | |...|
| Interest(n) | | Interest(n) | |
| --------------> | | ---------------> | |
| | | -------------------> |
| | | | |
| | | Data([n],c,[s]) | |
| | | <--------------- | |
| | | <------------------- |
| Data([n],c,[s]) | | | |
| <-------------- | | | |
Legend: n=name, c=content, s=signature
The following list describes the basic ICN concepts needed to discuss the implementation of this service abstraction.¶
Request-Reply Protocol (Interest and Data Packet):¶
Packet and Content Names:¶
Data Authenticity and Encryption:¶
Trust:¶
Segmenting and Versioning:¶
Packet and Frame:¶
ICN Node:¶
Forwarding Plane:¶
Information-Centric Networking (ICN):¶
Data Packet Immutability:¶
The terminology described above is the manifestation of intended semantics of NDN and CCNx operations (What do we expect the network to do?). In this section, we summarize the most commonly proposed use cases and interpretations.¶
The networking view of NDN and CCNx is that the request/reply protocol implements a basic, unreliable data transfer service for single, named packets.¶
Data transfer can be turned into a data transport service for application-level objects by additional logic. This transport logic must understand and construct the series of names needed to reassemble the segmented object. Various flavors of transport can be envisaged (reliable, streaming, mailbox, etc.).¶
In a more distributed systems view of the basic request/reply protocol, NDN and CCNx provide a distributed lookup service: given a key value (=name), the service will return the corresponding value.¶
A lookup service can be turned into a database access protocol by using the namespace structure to specify names as access keys into a database. Therefore, a name prefix stands for a collection or table of a database, while the rest of the name specifies the query expression to be executed.¶
The names as defined in this document for Interests and Data can refer to Remote Procedure call functions, their input arguments, and their results. For a comprehensive view of how to construct RPC or other remote invocation systems, see the Association for Computing Machinery (ACM) ICN paper on [RICE]. These capabilities can be further extended into a full distributed computing infrastructure such as that proposed in the ACM ICN paper [CFN].¶
The names as defined in this document for Interests and Data can refer to data collections to be subscribed and individual data objects to be published in a Publish-Subscribe application architecture. For a fully worked example of how to construct such an ICN-based system, see the ACM ICN paper [LESSONS-LEARNED].¶
This document has no IANA actions.¶
While the terms defined in this specification do not in and of themselves present new security considerations, the architectures that utilize the terms most certainly do. Readers should look at those specifications (e.g., [RFC8569] and [NDN]) where various security considerations are addressed in detail.¶
Some of the terms in this document use the words "trust", "trustworthy", or "trust model". We intend that these have their colloquial meanings; however, much work on trust, and specifically on trust schemas for ICN architectures, has been published in the last few years. For example, it is useful to look at [SCHEMATIZING-TRUST] for more information on the approaches taken to formalize notions of trust for current NDN and CCNx systems.¶
Marc Mosko provided much guidance and helpful precision in getting these terms carefully formed and the definitions precise. Marie-Jose Montpetit did a thorough IRSG review, which helped a lot to improve the text. Further comments during the IRSG Poll from Stephen Farrell, Ari Keraenen, Spencer Dawkins, Carsten Bormann, and Brian Trammell further improved the document. Additional helpful comments were received as part of the IESG conflict review from Mirja Kuehlewind and Benjamin Kaduk.¶