RFC 8793 ICN Terminology June 2020
Wissingh, et al. Informational [Page]
Internet Research Task Force (IRTF)
B. Wissingh
C. Wood
University of California Irvine
A. Afanasyev
Florida International University
L. Zhang
D. Oran
Network Systems Research & Design
C. Tschudin
University of Basel

RFC 8793

Information-Centric Networking (ICN): Content-Centric Networking (CCNx) and Named Data Networking (NDN) Terminology


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).

Status of This Memo

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.

Table of Contents

1. Introduction

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.

2. A Sketch of the Big Picture of ICN

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
Figure 1: Request-Reply Protocol of ICN Networking.

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:


Segmenting and Versioning:

Packet and Frame:

ICN Node:

Forwarding Plane:

3. Terms by Category

3.1. Generic Terms

Information-Centric Networking (ICN):

  • A networking architecture that retrieves Data packets in response to Interest packets. Content-Centric Networking (CCNx 1.x) and Named Data Networking (NDN) are two realizations (designs) of an ICN architecture.

Data Packet Immutability:

  • After a Data packet is created, the cryptographic signature binding the name to the content ensures that if either the content or the name changes, that change will be detected and the packet discarded. If the content carried in a Data packet is intended to be mutable, versioning of the name should be used so that each version uniquely identifies an immutable instance of the content. This allows disambiguation of various versions of content such that coordination among the various instances in a distributed system can be achieved.

4. Semantics and Usage

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.

4.1. Data Transfer

The networking view of NDN and CCNx is that the request/reply protocol implements a basic, unreliable data transfer service for single, named packets.

4.2. Data Transport

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.).

4.3. Lookup Service

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.

4.4. Database Access

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.

4.5. Remote Procedure Call

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].

4.6. Publish/Subscribe

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].

5. IANA Considerations

This document has no IANA actions.

6. Security Considerations

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.

7. References

7.1. Normative References

Krol, M., Mastorakis, S., Kutscher, D., and D. Oran, "Compute First Networking: Distributed Computing meets ICN", ACM ICN , DOI 10.1145/3357150.3357395, , <https://dl.acm.org/citation.cfm?id=3357395>.
Nichols, K., "Lessons Learned Building a Secure Network Measurement Framework using Basic NDN", ACM ICN , DOI 10.1145/3357150.3357397, , <https://dl.acm.org/citation.cfm?id=3357397>.
Raychaudhuri, D., Nagaraja, K., and A. Venkataramani, "MobilityFirst: a robust and trustworthy mobility-centric architecture for the future internet", ACM SIGMOBILE , Volume 16, Issue 3 , DOI 10.1145/2412096.2412098, , <https://dl.acm.org/citation.cfm?id=2412098>.
Named Data Networking, "NDN Packet Format Specification", <https://named-data.net/doc/ndn-tlv/>.
Dannewitz, C., Kutscher, D., Ohlman, B., Farrell, S., Ahlgren, B., and K. Holger, "Network of Information (NetInf) - An information-centric networking architecture", Computer Communications , Volume 36, Issue 7 , DOI 10.1016/j.comcom.2013.01.009, , <https://dl.acm.org/citation.cfm?id=2459643>.
Trossen, D., Tuononen, J., Xylomenos, G., Sarela, M., Zahemszky, A., Nikander, P., and T. Rinta-aho, "From Design for Tussle to Tussle Networking: PSIRP Vision and Use Cases", , <http://www.psirp.org/files/Deliverables/PSIRP-TR08-0001_Vision.pdf>.
Krol, M., Habak, K., Kutscher, D., Oran, D., and I. Psaras, "RICE: remote method invocation in ICN", ACM ICN , DOI 10.1145/3267955.3267956, , <https://dx.doi.org/10.1145/3267955.3267956>.
Yu, Y., Afanasyev, A., Clark, D., Claffy, K. C., Jacobson, V., and L. Zhang, "Schematizing Trust in Named Data Networking", ACM ICN , DOI 0.1145/2810156.2810170, , <https://dx.doi.org/10.1145/2810156.2810170>.

7.2. Informative References

Named Data Networking, "Named Data Networking: Executive Summary", , <https://named-data.net/project/execsummary/>.
Cerf, V., Burleigh, S., Hooke, A., Torgerson, L., Durst, R., Scott, K., Fall, K., and H. Weiss, "Delay-Tolerant Networking Architecture", RFC 4838, DOI 10.17487/RFC4838, , <https://www.rfc-editor.org/info/rfc4838>.
Shirey, R., "Internet Security Glossary, Version 2", FYI 36, RFC 4949, DOI 10.17487/RFC4949, , <https://www.rfc-editor.org/info/rfc4949>.
Eastlake 3rd, D. and T. Hansen, "US Secure Hash Algorithms (SHA and SHA-based HMAC and HKDF)", RFC 6234, DOI 10.17487/RFC6234, , <https://www.rfc-editor.org/info/rfc6234>.
Mosko, M., Solis, I., and C. Wood, "Content-Centric Networking (CCNx) Semantics", RFC 8569, DOI 10.17487/RFC8569, , <https://www.rfc-editor.org/info/rfc8569>.
Mosko, M., Solis, I., and C. Wood, "Content-Centric Networking (CCNx) Messages in TLV Format", RFC 8609, DOI 10.17487/RFC8609, , <https://www.rfc-editor.org/info/rfc8609>.


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.

Authors' Addresses

Bastiaan Wissingh
Christopher A. Wood
University of California Irvine
Alex Afanasyev
Florida International University
Lixia Zhang
David Oran
Network Systems Research & Design
Christian Tschudin
University of Basel