path: root/doc/rfc/rfc9518.txt

Independent Submission                                     M. Nottingham
Request for Comments: 9518                                 December 2023
Category: Informational                                                 
ISSN: 2070-1721


        Centralization, Decentralization, and Internet Standards

Abstract

   This document discusses aspects of centralization that relate to
   Internet standards efforts.  It argues that, while standards bodies
   have a limited ability to prevent many forms of centralization, they
   can still make contributions that assist in the decentralization of
   the Internet.

Status of This Memo

   This document is not an Internet Standards Track specification; it is
   published for informational purposes.

   This is a contribution to the RFC Series, independently of any other
   RFC stream.  The RFC Editor has chosen to publish this document at
   its discretion and makes no statement about its value for
   implementation or deployment.  Documents approved for publication by
   the RFC Editor are not candidates 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/rfc9518.

Copyright Notice

   Copyright (c) 2023 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
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   to this document.

Table of Contents

   1.  Introduction
   2.  Centralization
     2.1.  Centralization Can Be Harmful
     2.2.  Centralization Can Be Helpful
   3.  Decentralization
     3.1.  Decentralization Strategies
       3.1.1.  Federation
       3.1.2.  Distributed Consensus
       3.1.3.  Operational Governance
   4.  What Can Internet Standards Do?
     4.1.  Bolster Legitimacy
     4.2.  Focus Discussion of Centralization
     4.3.  Target Proprietary Functions
     4.4.  Enable Switching
     4.5.  Control Delegation of Power
     4.6.  Enforce Boundaries
     4.7.  Consider Extensibility Carefully
     4.8.  Reuse What Works
   5.  Future Work
   6.  Security Considerations
   7.  IANA Considerations
   8.  Informative References
   Acknowledgements
   Author's Address

1.  Introduction

   One of the Internet's defining features is its lack of any single
   point of technical, political, or economic control.  Arguably, that
   characteristic assisted the Internet's early adoption and broad
   reach: permission is not required to connect to, deploy an
   application on, or use the Internet for a particular purpose, so it
   can meet diverse needs and be deployed in many different
   environments.

   Although maintaining that state of affairs remains a widely espoused
   goal, consistently preserving it across the range of services and
   applications that people see as "the Internet" has proven elusive.
   Whereas early services like the Network News Transfer Protocol (NNTP)
   and email had multiple interoperable providers, many contemporary
   platforms for content and services are operated by single commercial
   entities without any interoperable alternative -- to the point where
   some have become so well-known and important to people's experiences
   that they are commonly mistaken for the Internet itself [Komaitis].

   These difficulties call into question what role architectural design
   -- in particular, that overseen by open standards bodies such as the
   IETF -- can and should play in controlling centralization of the
   Internet.

   This document argues that, while decentralized technical standards
   may be necessary to avoid centralization of Internet functions, they
   are not sufficient to achieve that goal because centralization is
   often caused by non-technical factors outside the control of
   standards bodies.  As a result, standards bodies should not fixate on
   preventing all forms of centralization; instead, they should take
   steps to ensure that the specifications they produce enable
   decentralized operation.

   Although this document has been discussed widely in the IETF
   community (see the Acknowledgements section), it represents the views
   of the author, not community consensus.  Its primary audience is the
   engineers who design and standardize Internet protocols.  Designers
   of proprietary protocols and applications can benefit from
   considering these issues, especially if they intend their work to be
   considered for eventual standardization.  Policymakers can use this
   document to help characterize abuses that involve centralized
   protocols and applications and evaluate proposed remedies for them.

   Section 2 defines centralization, explains why it is often
   undesirable but sometimes beneficial, and surveys how it occurs on
   the Internet.  Section 3 explores decentralization and highlights
   some relevant strategies, along with their limitations.  Section 4
   makes recommendations about the role that Internet standards can play
   in controlling centralization.  Section 5 concludes by identifying
   areas for future work.

2.  Centralization

   In this document, "centralization" is the state of affairs where a
   single entity or a small group of them can observe, capture, control,
   or extract rent from the operation or use of an Internet function
   exclusively.

   Here, "entity" could be a person, group, or corporation.  An
   organization might be subject to governance that mitigates
   centralization risk (see Section 3.1.3), but that organization is
   still a centralizing entity.

   "Internet function" is used broadly in this document.  Most directly,
   it might be an enabling protocol already defined by standards, such
   as IP [RFC791], BGP [RFC4271], TCP [RFC9293], or HTTP [HTTP].  It
   might also be a proposal for a new enabling protocol or an extension
   to an existing one.

   Because people's experience of the Internet are not limited to
   standards-defined protocols and applications, this document also
   considers centralization in functions built on top of standards --
   for example, social networking, file sharing, financial services, and
   news dissemination.  Likewise, the networking equipment, hardware,
   operating systems, and software that act as enabling technologies for
   the Internet can also impact centralization.  The supply of Internet
   connectivity to end users in a particular area or situation can
   exhibit centralization, as can the supply of transit between networks
   (so called "Tier 1" networks).

   This definition of centralization does not capture all types of
   centralization.  Notably, technical centralization (for example,
   where a machine or network link is a single point of failure) is
   relatively well understood by engineers; it can be mitigated,
   typically by distributing a function across multiple components.  As
   we will see, such techniques might address that type of
   centralization while failing to prevent control of the function
   falling into few hands.  A failure because of a cut cable, power
   outage, or failed server is well understood by the technical
   community but is qualitatively different from the issues encountered
   when a core Internet function has a gatekeeper.

   Likewise, political centralization (for example, where a country is
   able to control how a function is supplied across the whole Internet)
   is equally concerning but is not considered in depth here.

   Even when centralization is not currently present in a function, some
   conditions make it more likely that centralization will emerge in the
   future.  This document uses "centralization risk" to characterize
   that possibility.

2.1.  Centralization Can Be Harmful

   Many engineers who participate in Internet standards efforts have an
   inclination to prevent and counteract centralization because they see
   the Internet's history and architecture as incompatible with it.  As
   a "large, heterogeneous collection of interconnected systems" [BCP95]
   the Internet is often characterized as a "network of networks" whose
   operators relate as peers that agree to facilitate communication
   rather than experiencing coercion or requiring subservience to
   others' requirements.  This focus on independence of action is
   prevalent in the Internet's design -- for example, in the concept of
   an "autonomous system".

   Reluctance to countenance centralization is also rooted in the many
   potentially damaging effects that have been associated with it,
   including:

   *  _Power Imbalance_: When a third party has unavoidable access to
      communications, they gain informational and positional advantages
      that allow observation of behavior (the "panopticon effect") and
      shaping or even denial of behavior (the "chokepoint effect"):
      capabilities that those parties (or the states that have authority
      over them) can use for coercive ends [FarrellH] or even to disrupt
      society itself.  Just as [Madison] describes good governance of
      the US states, good governance of the Internet requires that power
      over any function not be consolidated in one place without
      appropriate checks and balances.

   *  _Limits on Innovation_: A party with the ability to control
      communication can preclude the possibility of "permissionless
      innovation", i.e., the ability to deploy new, unforeseen
      applications without requiring coordination with parties other
      than those you are communicating with.

   *  _Constraints on Competition_: The Internet and its users benefit
      from robust competition when applications and services are
      available from many providers, especially when those users can
      build their own applications and services based upon interoperable
      standards.  When a centralized service or platform must be used
      because no substitutes are suitable, it effectively becomes an
      essential facility, which opens the door to abuse of power.

   *  _Reduced Availability_: Availability of the Internet (and
      applications and services built upon it) improves when there are
      many ways to obtain access.  While service availability can
      benefit from the focused attention of a large centralized
      provider, that provider's failure can have a disproportionate
      impact on availability.

   *  _Monoculture_: The scale available to a centralized provider can
      magnify minor flaws in features to a degree that can have broad
      consequences.  For example, a single codebase for routers elevates
      the impact of a bug or vulnerability; a single recommendation
      algorithm for content can have severe social impact.  Diversity in
      functions' implementations leads to a more robust outcome when
      viewed systemically because "progress is the outcome of a trial-
      and-error evolutionary process of many agents interacting freely"
      [Aligia].

   *  _Self-Reinforcement_: As widely noted (e.g., see [Abrahamson]), a
      centralized provider's access to data allows it the opportunity to
      make improvements to its offerings while denying such access to
      others.

   The relationship between these harms and centralization is often
   complex.  It is not always the case that centralization will lead to
   them; when it does, there is not always a direct and simple trade-
   off.

   For example, consider the relationship between centralization and
   availability.  A centrally operated system might be more available
   because of the resources available to a larger operator, but their
   size creates greater impact when a fault is encountered.
   Decentralized systems can be more resilient in the face of some forms
   of failure but less so in other ways; for example, they may be less
   able to react to systemic issues and might be exposed to a larger
   collection of security vulnerabilities in total.  As such, it cannot
   be said that centralization reduces availability in all cases: nor
   does it improve it in all cases.

   This tension can be seen in areas like the cloud and mobile Internet
   access.  If a popular cloud-hosting provider were to become
   unavailable (whether for technical or other reasons), many Internet
   experiences might be disrupted (especially due to the multiple
   dependencies that a modern website often has; see [Kashaf]).
   Likewise, a large mobile Internet access provider might have an
   outage that affects hundreds of thousands of its users or more --
   just as previous issues at large telephone companies precipitated
   widespread outages [PHONE].

   In both cases, the services are not technically centralized; these
   operators have strong incentives to have multiple redundancies in
   place and use various techniques to mitigate the risk of any one
   component failing.  However, they generally do rely upon a single
   codebase, a limited selection of hardware, a unified control plane,
   and a uniform administrative practice: each of which might
   precipitate a widespread failure.

   If there were only one provider for these services (like the
   telephone networks of old), they would easily be considered to be
   centralized in a way that has significant impact upon availability.
   However, many cloud providers offer similar services.  In most
   places, there are multiple mobile operators available.  That weakens
   the argument that there is a link between centralization and their
   availability because the function's users can switch to other
   providers or use more than one provider simultaneously; see
   Section 4.4.

   These circumstances suggest one area of inquiry when considering the
   relationship between centralization and availability of a given
   function: what barriers are there to switching to other providers
   (thereby making any disruptions temporary and manageable) or to using
   multiple providers simultaneously (to mask the failure of a single
   operator)?

   Another example of the need for nuance can be seen when evaluating
   competitive constraints.  While making provision of various Internet
   functions more competitive may be a motivation for many engineers,
   only courts (and sometimes regulators) have the authority to define a
   relevant market and determine that a behavior is anticompetitive.  In
   particular, market concentration does not always indicate competition
   issues; therefore, what might be considered undesirable
   centralization by the technical community might not attract
   competition regulation.

2.2.  Centralization Can Be Helpful

   The potential damaging effects of centralization listed above are
   widely appreciated.  Less widely explored is the reliance on
   centralization by some protocols and applications to deliver their
   functionality.

   Centralization is often present due to technical necessity.  For
   example, a single globally coordinated "source of truth" is by nature
   centralized -- such as in the root zone of the Domain Name System
   (DNS), which allows human-friendly naming to be converted into
   network addresses in a globally consistent fashion.

   Or, consider IP address allocation.  Internet routing requires
   addresses to be allocated uniquely, but if a single government or
   company were to capture the addressing function, the entire Internet
   would be at risk of abuse by that entity.  Similarly, the Web's trust
   model requires a Certificate Authority (CA) to serve as the root of
   trust for communication between browsers and servers, bringing the
   centralization risk, which needs to be considered in the design of
   that system.

   Protocols that need to solve the "rendezvous problem" to coordinate
   communication between two parties who are not in direct contact also
   require centralization.  For example, chat protocols need to
   coordinate communication between two parties that wish to talk; while
   the actual communication can be direct between them (so long as the
   protocol facilitates that), the endpoints' mutual discovery typically
   requires a third party at some point.  From the perspective of those
   two users, the rendezvous function has a centralization risk.

   Even when not strictly necessary, centralization can create benefits
   for a function's users and for society.

   For example, it has long been recognized that the efficiencies that
   come with economies of scale can lead to concentration [Demsetz].
   Those efficiencies can be passed on to users as higher quality
   products and lower costs, and they might even enable provision of a
   function that was not viable at smaller scale.

   Complex and risky functions like financial services (e.g., credit
   card processing) are often concentrated into a few specialized
   organizations where they can receive the focused attention and
   expertise that they require.

   Centralization can also provide an opportunity for beneficial
   controls to be imposed.  [Schneider2] notes that "centralized
   structures can have virtues, such as enabling publics to focus their
   limited attention for oversight, or forming a power bloc capable of
   challenging less-accountable blocs that might emerge.  Centralized
   structures that have earned widespread respect in recent centuries --
   including governments, corporations, and nonprofit organizations --
   have done so in no small part because of the intentional design that
   went into those structures".

   This can be seen when a function requires governance to realize
   common goals and protect minority interests.  For example, content
   moderation functions impose community values that many see as a
   benefit.  Of course, they can also be viewed as a choke point where
   inappropriate controls are able to be imposed if that governance
   mechanism has inadequate oversight, transparency, or accountability.

   Ultimately, deciding when centralization is beneficial is a judgment
   call.  Some protocols cannot operate without a centralized function;
   others might be significantly enhanced for certain use cases if a
   function is centralized or might merely be more efficient.  Although,
   in general, centralization is most concerning when it is not broadly
   held to be necessary or beneficial; when it has no checks, balances,
   or other mechanisms of accountability; when it selects "favorites"
   that are difficult (or impossible) to displace; and when it threatens
   the architectural features that make the Internet successful.

3.  Decentralization

   While the term "decentralization" has a long history of use in
   economics, politics, religion, and international development, [Baran]
   gave one of the first definitions relevant to computer networking as
   a condition when "complete reliance upon a single point is not always
   required".

   Such technical centralization (while not a trivial topic) is
   relatively well understood.  Avoiding all forms of centralization --
   including non-technical ones -- using only technical tools (like
   protocol design) is considerably more difficult.  Several issues are
   encountered.

   First, and most critically, technical decentralization measures have,
   at best, limited effects on non-technical forms of centralization.
   Or, per [Schneider1], "decentralized technology alone does not
   guarantee decentralized outcomes".  As explored below in Section 3.1,
   technical measures are better characterized as necessary but
   insufficient to achieve full decentralization of a function.

   Second, decentralizing a function requires overcoming challenges that
   centralized ones do not face.  A decentralized function can be more
   difficult to adapt to user needs (for example, introducing new
   features or experimenting with user interfaces) because doing so
   often requires coordination between many different actors
   [Marlinspike].  Economies of scale are more available to centralized
   functions, as is data that can be used to refine a function's design.
   All of these factors make centralized solutions more attractive to
   service providers and, in some cases, can make a decentralized
   solution uneconomic.

   Third, identifying which aspects of a function to decentralize can be
   difficult, both because there are often many interactions between
   different types and sources of centralization and because
   centralization sometimes only becomes clear after the function is
   deployed at scale.  Efforts to decentralize often have the effect of
   merely shifting centralization to a different place -- for example,
   in its governance, implementation, deployment, or ancillary
   functions.

   For example, the Web was envisioned and widely held to be a
   decentralizing force in its early life.  Its potential as an enabler
   of centralization only became apparent when large websites
   successfully leveraged network effects (and secured legal
   prohibitions against interoperability, thus increasing switching
   costs; see [Doctorow]) to achieve dominance of social networking,
   marketplaces, and similar functions.

   Fourth, different parties might have good-faith differences on what
   "sufficiently decentralized" means based upon their beliefs,
   perceptions, and goals.  Just as centralization is a continuum, so is
   decentralization, and not everyone agrees what the "right" level or
   type is, how to weigh different forms of centralization against each
   other, or how to weigh potential centralization against other
   architectural goals (such as security or privacy).

   These tensions can be seen, for example, in the DNS.  While some
   aspects of the system are decentralized -- for example, the
   distribution of the lookup function to local servers that users have
   the option to override -- an essentially centralized aspect of the
   DNS is its operation as a name space: a single global "source of
   truth" with inherent (if beneficial) centralization in its
   management.  ICANN mitigates the associated risk through multi-
   stakeholder governance (see Section 3.1.3).  While many believe that
   this arrangement is sufficient and might even have desirable
   qualities (such as the ability to impose community standards over the
   operation of the name space), others reject ICANN's oversight of the
   DNS as illegitimate, favoring decentralization based upon distributed
   consensus protocols rather than human governance [Musiani].

   Fifth, decentralization unavoidably involves adjustments to the power
   relationships between protocol participants, especially when it opens
   up the possibility of centralization elsewhere.  As [Schneider2]
   notes, decentralization "appears to operate as a rhetorical strategy
   that directs attention toward some aspects of a proposed social order
   and away from others", so "we cannot accept technology as a
   substitute for taking social, cultural, and political considerations
   seriously".  Or, more bluntly, "without governance mechanisms in
   place, nodes may collude, people may lie to each other, markets can
   be rigged, and there can be significant cost to people entering and
   exiting markets" [Bodo].

   For example, while blockchain-based cryptocurrencies purport to
   address the centralization inherent in existing currencies through
   technical means, many exhibit considerable concentration of power due
   to voting/mining power, distribution of funds, and diversity of the
   codebase [Makarov].  Overreliance on technical measures also brings
   an opportunity for latent, informal power structures that have their
   own risks -- including centralization [Freeman].

   Overall, decentralizing a function requires considerable work, is
   inherently political, and involves a large degree of uncertainty
   about the outcome.  If one considers decentralization as a larger
   social goal (in the spirit of how the term is used in other, non-
   computing contexts), merely rearranging technical functions may lead
   to frustration.  "A distributed network does not automatically yield
   an egalitarian, equitable or just social, economic, political
   landscape" [Bodo].

3.1.  Decentralization Strategies

   This section examines some common strategies that are employed to
   decentralize Internet functions and discusses their limitations.

3.1.1.  Federation

   Protocol designers often attempt to address centralization through
   federation, i.e., designing a function in a way that uses independent
   instances that maintain connectivity and interoperability to provide
   a single cohesive service.  Federation promises to allow users to
   choose the instance they associate with and accommodates substitution
   of one instance for another, lowering switching costs.

   However, federation alone is insufficient to prevent or mitigate
   centralization of a function because non-technical factors can create
   pressure to use a central solution.

   For example, the email suite of protocols needs to route messages to
   a user even when that user changes network locations or becomes
   disconnected for a long period.  To facilitate this, SMTP [RFC5321]
   defines a specific role for routing users' messages, the Message
   Transfer Agent (MTA).  By allowing anyone to deploy an MTA and
   defining rules for interconnecting them, the protocol avoids a
   requirement for a single central server in that role; users can (and
   often do) choose to delegate it to someone else or they can run their
   own MTA.

   Running one's own MTA has become considerably more onerous over the
   years due, in part, to the increasingly complex mechanisms introduced
   to fight unwanted commercial emails.  These costs create an incentive
   to delegate one's MTA to a third party who has the appropriate
   expertise and resources, contributing to market concentration
   [Holzbauer].

   Additionally, the measures that MTAs use to identify unwanted
   commercial emails are often site specific.  Because large MTAs handle
   so many more addresses, there is a power imbalance with smaller ones;
   if a large MTA decides that email from a small one is unwanted, there
   is significant impact on its ability to function and little recourse.

   The Extensible Messaging and Presence Protocol (XMPP) [RFC6120] is a
   chat protocol that demonstrates another issue with federation: the
   voluntary nature of technical standards.

   Like email, XMPP is federated to facilitate the rendezvous of users
   from different systems - if they allow it.  While some XMPP
   deployments do support truly federated messaging (i.e., a person
   using service A can interoperably chat with someone using service B),
   many of the largest do not.  Because federation is voluntary, some
   operators captured their users into a single service, deliberately
   denying them the benefits of global interoperability.

   The examples above illustrate that, while federation can create the
   conditions necessary for a function to be decentralized, it does not
   guarantee that outcome.

3.1.2.  Distributed Consensus

   Increasingly, distributed consensus technologies (such as a
   blockchain) are touted as a solution to centralization.  A complete
   survey of this rapidly changing area is beyond the scope of this
   document, but we can generalize about its properties.

   These techniques typically guarantee proper performance of a function
   using cryptographic techniques (often, an append-only transaction
   ledger).  They attempt to avoid centralization by distributing the
   operation of a function to members of a sometimes large pool of
   protocol participants.  Usually, the participants are unknown and
   untrusted, and a particular task's assignment to a node for handling
   cannot be predicted or controlled.

   Sybil attacks (where a party or coordinated parties cheaply create
   enough protocol participants to affect how consensus is judged) are a
   major concern for these protocols because they would have the effect
   of concentrating power into the hands of the attacker.  Therefore,
   they encourage diversity in the pool of participants using indirect
   techniques, such as proof-of-work (where each participant has to show
   a significant consumption of resources) or proof-of-stake (where each
   participant has some other incentive to execute correctly).

   While these measures can be effective in decentralizing a function's
   operation, other aspects of its provision can still be centralized:
   for example, governance of its design, creation of shared
   implementations, and documentation of wire protocols.  That need for
   coordination is an avenue for centralization even when the function's
   operation remains decentralized.  For example, the Ethereum "merge"
   demonstrated that the blockchain could address environmental concerns
   but only through coordinated community effort and governance:
   coordination that was benign in most eyes but, nevertheless,
   centralized [ETHEREUM].

   Furthermore, a protocol or an application composed of many functions
   can use distributed consensus for some but still be centralized
   elsewhere -- either because those other functions cannot be
   decentralized (most commonly, rendezvous and global naming; see
   Section 2.2) or because the designer has chosen not to because of the
   associated costs and lost opportunities.

   These potential shortcomings do not rule out the use of distributed
   consensus technologies in every instance, but they do merit caution
   against uncritically relying upon these technologies to avoid or
   mitigate centralization.  Too often, the use of distributed consensus
   is perceived as imbuing all parts of a project with
   "decentralization".

3.1.3.  Operational Governance

   Federation and distributed consensus can both create the conditions
   for the provision of a function by multiple providers, but they
   cannot guarantee it.  However, when providers require access to a
   resource or cooperation of others to provide that service, that choke
   point can itself be used to influence provider behavior -- including
   in ways that can counteract centralization.

   In these circumstances, some form of governance over that choke point
   is necessary to assure the desired outcome.  Often, this is through
   the establishment of a multi-stakeholder body, which is an
   institution that includes representatives of the different kinds of
   parties that are affected by the system's operation ("stakeholders")
   in an attempt to make well-reasoned, legitimate, and authoritative
   decisions.

   A widely studied example of this technique is the governance of the
   DNS name space, which exhibits centralization as a "single source of
   truth" [Moura].  That source of truth is overseen by the Internet
   Corporation for Assigned Names and Numbers (ICANN)
   <https://www.icann.org/resources/pages/governance/governance-en>, a
   global multi-stakeholder body with representation from end users,
   governments, operators, and others.

   Another example is the governance of the Web's trust model,
   implemented by web browsers as relying parties that have strong
   incentives to protect user privacy and security and CAs as trust
   anchors that have a strong incentive to be included in browser trust
   stores.  To promote the operational and security requirements
   necessary to provide the desired properties, the CA/Browser Forum
   <https://cabforum.org> was established as an oversight body that
   involves both parties as stakeholders.

   These examples are notable in that the governance mechanism is not
   specified in the protocol documents directly; rather, they are
   layered on operationally, but in a manner that takes advantage of
   protocol features that enable the imposition of governance.

   Governance in this manner is suited to very limited functions like
   the examples above.  Even then, the setup and ongoing operation of a
   governance mechanism is not trivial, and their legitimacy may be
   difficult to establish and maintain (e.g., see [Palladino]); by their
   nature, they are vulnerable to capture by the interests that are
   being governed.

4.  What Can Internet Standards Do?

   Given the limits of decentralization techniques like federation and
   distributed consensus, the voluntary nature of standards compliance,
   and the powerful forces that can drive centralization, it is
   reasonable to ask what standards efforts like those at the IETF can
   do to accommodate helpful centralization while avoiding the
   associated harms and acknowledging that the distinction itself is a
   judgment call and, therefore, inherently political.

   The subsections below suggest a few concrete, meaningful steps that
   standards bodies can take.

4.1.  Bolster Legitimacy

   Where technical standards have only limited ability to control
   centralization of the Internet, legal standards (whether regulation,
   legislation, or case law) show more promise and are actively being
   considered and implemented in various jurisdictions.  However,
   regulating the Internet is risky without a firm grounding in the
   effects on the architecture informed by a technical viewpoint.

   That viewpoint can and should be provided by the Internet standards
   community.  To effectively do so, its institutions must be seen as
   legitimate by the relevant parties -- for example, competition
   regulators.  If the IETF is perceived as representing or being
   controlled by "big tech" concerns or only US-based companies, its
   ability to guide decisions that affect the Internet will be
   diminished considerably.

   The IETF already has features that arguably provide considerable
   legitimacy.  Examples of these features include open participation
   and representation by individuals rather than by companies, both of
   which enhance input legitimacy); a well-defined process with multiple
   layers of appeals and transparency, which contributes to throughput
   legitimacy; and a long history of successful Internet standards,
   which provides perhaps the strongest source of legitimacy for the
   IETF -- its output.

   However, it is also widely recognized that the considerable costs
   (not just financial) involved in successfully participating in the
   IETF have a tendency to favor larger companies over smaller concerns.
   Additionally, the specialized and highly technical nature of the work
   creates barriers to entry for non-technical stakeholders.  These
   factors have the potential to reduce the legitimacy of the IETF's
   decisions, at least in some eyes.

   Efforts to address these shortcomings are ongoing; for example, see
   [RFC8890].  Overall, bolstering the legitimacy of the organization
   should be seen as a continuous effort.

   When engaging in external efforts, the IETF community (especially its
   leadership) should keep firmly in mind that its voice is most
   authoritative when focused on technical and architectural impact.

4.2.  Focus Discussion of Centralization

   Centralization and decentralization are increasingly being raised in
   technical standards discussions.  Any claim needs to be critically
   evaluated.  As discussed in Section 2, not all centralization is
   automatically harmful.  Per Section 3, decentralization techniques do
   not automatically address all centralization harms and may bring
   their own risks.

   However, standards participants rarely have the expertise or
   information available to completely evaluate those claims, because
   the analysis involves not only technical factors, but also economic,
   social, commercial, and legal aspects.  For example, economies of
   scale can cause concentration due to the associated efficiencies
   [Demsetz], and so determining whether that concentration is
   appropriate requires a detailed economic analysis that is not in
   scope for a technical standards body.  Furthermore, claims of
   centralization may have other motivations; in particular, they can be
   proxies for power struggles between actors with competing interests,
   and a claim of centralization might be used to deny market
   participants and (perhaps more importantly) users the benefits of
   standardization.

   Therefore, approaches like requiring a "Centralization
   Considerations" section in documents, gatekeeping publication on a
   centralization review, or committing significant resources to
   searching for centralization in protocols are unlikely to improve the
   Internet.

   Similarly, refusing to standardize a protocol because it does not
   actively prevent all forms of centralization ignores the very limited
   power that standards efforts have to do so.  Almost all existing
   Internet protocols -- including IP, TCP, HTTP, and DNS -- fail to
   prevent centralized applications from using them.  While the
   imprimatur of the standards track [RFC2026] is not without value,
   merely withholding it cannot prevent centralization.

   Thus, discussions should be very focused and limited, and any
   proposals for decentralization should be detailed so their full
   effects can be evaluated.  [Schneider1] implores those who propose
   decentralization to be "really, really clear about what particular
   features of a system a given design seeks to decentralize" and
   promotes considered use of tools like separation of powers and
   accountability from "old, institutional liberal political theory".

   When evaluating claims that a given proposal is centralized, the
   context of those statements should be examined for presuppositions,
   assumptions, and omissions.  [Bacchi] offers one framework for
   critical interrogations, which can be adapted for centralization-
   related discussions:

   1.  What is the nature of the centralization that is represented as
       being problematic?

   2.  What deep-seated presuppositions or assumptions (conceptual
       logics) underlie this representation of the "problem"?

   3.  How has this representation of the problem come about?

   4.  What is left unproblematic in this problem representation?  Where
       are the silences?  Can the "problem" be conceptualized
       differently?

   5.  What effects are produced by this representation of the
       "problem"?

   6.  How and where has this representation of the "problem" been
       produced, disseminated, and defended?  How has it been and/or how
       can it be disrupted and replaced?

4.3.  Target Proprietary Functions

   Functions that are widely used but lacking in interoperability are
   ripe for standardization efforts.  Targeting prominent and
   proprietary functions (e.g., chat) is appropriate, but so are smaller
   efforts to improve interoperability and portability of specific
   features that are often used to lock users into a platform, for
   example, a format for lists of contacts in a social network.

   A common objection to this approach is that adoption is voluntary;
   there are no "standards police" to mandate their use or enforce
   correct implementation.  For example, specifications like
   [ACTIVITYSTREAMS] were available for some time without being used in
   a federated manner by commercial social-networking providers.

   That objection ignores the fact that while standards aren't
   mandatory, legal regulation is.  Legal mandates for interoperability
   are increasingly proposed by policymakers as a remedy for competition
   issues (e.g., see [DMA]).  This appetite for regulation presents an
   opportunity for new specifications to decentralize these functions,
   backed by a legal mandate in combination with changing norms and the
   resulting market forces [Lessig].

   That opportunity also presents a risk, if the resulting legal
   regulation is at odds with the Internet architecture.  Successfully
   creating standards that work in concert with legal regulation
   presents many potential pitfalls and will require new and improved
   capabilities (especially liaison) and considerable effort.  If the
   technical community does not make that effort, it is likely that
   regulators will turn to other sources for interoperability
   specifications.

4.4.  Enable Switching

   The ability to switch between different function providers is a core
   mechanism to control centralization.  If users are unable to switch,
   they cannot exercise choice or fully realize the value of their
   efforts because, for example, "learning to use a vendor's product
   takes time, and the skill may not be fully transferable to a
   competitor's product if there is inadequate standardization"
   [FarrellJ].

   Therefore, standards should have an explicit goal of facilitating
   users switching between implementations and deployments of the
   functions they define or enable.

   One necessary condition for switching is the availability of
   alternatives; breadth and diversity of implementation and deployment
   are required.  For example, if there is only a single implementation
   of a protocol, applications that use it are vulnerable to the control
   it has over their operation.  Even open source projects can be an
   issue in this regard if there are factors that make forking difficult
   (for example, the cost of maintaining that fork).  Section 2.1 of
   [RFC5218] explores some factors in protocol design that encourage
   diversity of implementation.

   The cost of substituting an alternative implementation or deployment
   by users is another important factor to consider.  This includes
   minimizing the amount of time, resources, expertise, coordination,
   loss of functionality, and effort required to use a different
   provider or implementation -- with the implication that the standard
   needs to be functionally complete and specified precisely enough to
   allow substitution.

   These goals of completeness and diversity are sometimes at odds.  If
   a standard becomes extremely complex, it may discourage
   implementation diversity because the cost of a complete
   implementation is too high (consider web browsers).  On the other
   hand, if the specification is too simple, it may not enable easy
   switching, especially if proprietary extensions are necessary to
   complete it (see Section 4.7).

   One objection to protocols that enable easy switching is that they
   reduce the incentives for implementation by commercial vendors.
   While a completely commoditized protocol might not allow
   implementations to differentiate themselves, they provide
   opportunities for specialization and improvement elsewhere in the
   value chain [Christensen].  Well-timed standards efforts leverage
   these forces to focus proprietary interests on top of open technology
   rather than as a replacement for it.

4.5.  Control Delegation of Power

   The users of some functions might realize substantial benefits if
   they are provided by a third party in communication.  Adding a new
   party to communication can improve the following:

   *  _Efficiency_: Many functions on the Internet are more efficient
      when performed at a higher scale.  For example, a content delivery
      network can offer services at a fraction of the financial and
      environmental cost that someone serving content themselves would
      otherwise pay because of the scale they operate at.  Likewise, a
      two-sided market platform can introduce sizable efficiencies over
      pair-wise buyer/seller trading [Spulber].

   *  _Simplicity_: Completely disintermediating communication can shift
      the burden of functions onto endpoints.  This can cause increased
      cognitive load for users; for example, compare commercial social-
      networking platforms with self-hosted efforts.

   *  _Specialization_: Having a function consolidated into a few hands
      can improve outcomes because of the resulting specialization.  For
      example, services overseen by professional administrators are
      often seen to have a better security posture and improved
      availability.

   *  _Privacy_: For some functions, user privacy can be improved by
      consolidating their activity to prevent individual behaviors from
      being discriminated from each other [Chaum].  Introduction of a
      third party can also enforce functional boundaries -- for example,
      to reduce the need for users to trust potentially malicious
      endpoints, as seen in the so-called "oblivious" protocols (e.g.,
      [RFC9230]) that allow end users to hide their identity from
      services while still accessing them.

   However, if that new party is able to make their participation
   "sticky" -- for example, by leveraging their position in the network
   to require use of an intermediary, by exploiting their access to
   data, or because it is difficult to switch to another provider of the
   function -- there is a risk of centralization.

   Most often, third parties are added to functions as "intermediaries"
   or in designated "agent" roles.  Designing such functions with
   thoughtful constraints on these roles can prevent at least the most
   egregious abuses of such power.

   When adding new parties to a function, two guidelines have proven
   useful.  First, third parties should only be interposed into
   communication when at least one of the primary parties takes a
   positive action to do so.  Second, third parties should have their
   ability to observe or control communication limited to what is
   necessary to perform their intended function.

   For example, early deployments of HTTP allowed intermediaries to be
   interposed by the network without knowledge of the endpoints, and
   those intermediaries could see and change the full content of traffic
   by default -- even when they were only intended to perform basic
   functions such as caching.  Because of the introduction of HTTPS and
   the CONNECT method (see Section 9.3.6 of [HTTP]), combined with
   efforts to encourage its adoption, those intermediaries are now
   required to be explicitly interposed by one endpoint, and they only
   have access to basic routing information.

   See [THOMSON-TMI] for more guidance on protocol intermediation.

   The term "intermediary" is also used (often in legal and regulatory
   contexts) more broadly than it has been in protocol design; for
   example, an auction website that intermediates between buyers and
   sellers is considered an intermediary, even though it is not formally
   an intermediary in HTTP (see Section 3.7 of [HTTP]).  Protocol
   designers can address the centralization associated with this kind of
   intermediation by standardizing the function rather than restricting
   the capabilities of the underlying protocols; see Section 4.3.

4.6.  Enforce Boundaries

   Most Internet protocols and applications depend on other, "lower-
   layer" functions and their implementations.  The features,
   deployment, and operation of these dependencies can become
   centralization risks for the functions and applications built "on
   top" of them.

   For example, application protocols require a network to function;
   therefore, a degree of power over communication is available to the
   network provider.  They might block access to, slow down, or change
   the content of a specific service for financial, political,
   operational, or criminal reasons, creating a disincentive (or even
   removing the ability) to use a specific provider of a function.  By
   selectively hindering the use of some services but not others,
   network interventions can be composed to create pressure to use those
   other services -- intentionally or not.

   Techniques like encryption can discourage such centralization by
   enforcing such boundaries.  When the number of parties who have
   access to the content of communication is limited, other parties who
   handle it but are not party to it can be prevented from interfering
   with and observing it.  Although those parties might still prevent
   communication, encryption also makes it more difficult to
   discriminate a target from other users' traffic.

4.7.  Consider Extensibility Carefully

   The Internet's ability to evolve is critical, allowing it to meet new
   requirements and adapt to new conditions without requiring a "flag
   day" to upgrade implementations.  Typically, functions accommodate
   evolution by defining extension interfaces, which allow optional
   features to be added or change over time in an interoperable fashion.

   However, these interfaces can also be leveraged by a powerful entity
   if they can change the target for meaningful interoperability by
   adding proprietary extensions to a standard.  This is especially true
   when the core standard does not itself provide sufficient utility on
   its own.

   For example, the extreme flexibility of SOAP [SOAP] and its failure
   to provide significant standalone value allowed vendors to require
   use of their preferred extensions, favoring those who had more market
   power.

   Therefore, standards efforts should focus on providing concrete
   utility to the majority of their users as published, rather than
   being a "framework" where interoperability is not immediately
   available.  Internet functions should not make every aspect of their
   operation extensible; boundaries between modules should be designed
   in a way that allows evolution, while still offering meaningful
   functionality.

   Beyond allowing evolution, well-considered interfaces can also aid
   decentralization efforts.  The structural boundaries that emerge
   between the sub-modules of the function -- as well as those with
   adjacent functions -- provide touchpoints for interoperability and an
   opportunity for substitution of providers.

   In particular, if the interfaces of a function are well-defined and
   stable, there is an opportunity to use different providers for that
   function.  When those interfaces are open standards, change control
   resides with the technical community instead of remaining in
   proprietary hands, further enhancing stability and enabling (but not
   ensuring) decentralization.

4.8.  Reuse What Works

   When centralization is purposefully allowed in an Internet function,
   protocol designers often attempt to mitigate the associated risks
   using technical measures such as federation (see Section 3.1.1) and
   operational governance structures (see Section 3.1.3).

   Protocols that successfully do so are often reused to avoid the
   considerable cost and risk of reimplementing those mitigations.  For
   example, if a protocol requires a coordinated global naming function,
   incorporating the Domain Name System is usually preferable to
   establishing a new system.

5.  Future Work

   This document has argued that, while standards bodies have little
   means of effectively controlling or preventing centralization of the
   Internet through protocol design, there are still concrete and useful
   steps they can take to improve the Internet.

   Those steps might be elaborated upon and extended in future work;
   however, it is doubtless there is more that can be done.  New
   decentralization techniques might be identified and examined; what we
   learn from relationships with other, more effective regulators in
   this space can be documented.

   Some have suggested creating a how-to guide or checklist for dealing
   with centralization.  Because centralization is so contextual and so
   varied in how it manifests, this might best be attempted within very
   limited areas -- for example, for a particular type of function or a
   function at a particular layer.

   The nature of centralization also deserves further study; in
   particular, its causes.  While there is much commentary on factors
   like network effects and switching costs, other aspects -- such as
   behavioral, cognitive, social, and economic factors have received
   comparatively little attention, although that is changing (e.g.,
   [Fletcher]).

6.  Security Considerations

   This document does not have a direct security impact on Internet
   protocols.  That said, failure to consider centralization might cause
   a myriad of security issues; see Section 2.1 for a preliminary
   discussion.

7.  IANA Considerations

   This document has no IANA actions.

8.  Informative References

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              Prodromou, E., Ed. and J. Snell, Ed., "Activity Streams
              2.0", W3C Recommendation, 23 May 2017,
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              Ostrom, and Beyond", Governance: An International Journal
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              2012, <https://onlinelibrary.wiley.com/doi/abs/10.1111/
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              Represented to be?' approach", Chapter 2, Engaging with
              Carol Bacchi, 2012, <https://library.oapen.org/bitstream/
              handle/20.500.12657/33181/560097.pdf?sequence=1#page=34>.

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              BCP 95, RFC 3935, October 2004.

              <https://www.rfc-editor.org/info/bcp95>

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              Union, "Regulation (EU) 2022/1925 of the European
              Parliament and of the Council of 14 September 2022 on
              contestable and fair markets in the digital sector and
              amending Directives (EU) 2019/1937 and (EU) 2020/1828
              (Digital Markets Act)", OJ L 265/1, 12.10.2022, September
              2022, <https://eur-lex.europa.eu/legal-content/EN/
              TXT/?uri=CELEX%3A32022R1925>.

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              interoperability>.

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              How Global Economic Networks Shape State Coercion",
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              <https://doi.org/10.2307/2555402>.

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              Competition Policy", DOI 10.2139/ssrn.4389681, March 2023,
              <https://doi.org/10.2139/ssrn.4389681>.

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              July 2022,
              <https://www.usenix.org/system/files/atc22-holzbauer.pdf>.

   [HTTP]     Fielding, R., Ed., Nottingham, M., Ed., and J. Reschke,
              Ed., "HTTP Semantics", STD 97, RFC 9110,
              DOI 10.17487/RFC9110, June 2022,
              <https://www.rfc-editor.org/info/rfc9110>.

   [Kashaf]   Kashaf, A., Sekar, V., and Y. Agarwal, "Analyzing Third
              Party Service Dependencies in Modern Web Services: Have We
              Learned from the Mirai-Dyn Incident?",
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              <https://dl.acm.org/doi/pdf/10.1145/3419394.3423664>.

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              regulation.html>.

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              the Proper Checks and Balances Between the Different
              Departments", The Federalist Papers, No. 51, February
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              Bitcoin Market", National Bureau of Economic Research,
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              <https://www.nber.org/papers/w29396>.

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              May 2016,
              <https://signal.org/blog/the-ecosystem-is-moving/>.

   [Moura]    Moura, G., Castro, S., Hardaker, W., Wullink, M., and C.
              Hesselman, "Clouding up the Internet: how centralized is
              DNS traffic becoming?", DOI 10.1145/3419394.3423625,
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              phone-service/0db94ac7-89f0-446e-ba33-c126c751b251/>.

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              3", BCP 9, RFC 2026, DOI 10.17487/RFC2026, October 1996,
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   [RFC4271]  Rekhter, Y., Ed., Li, T., Ed., and S. Hares, Ed., "A
              Border Gateway Protocol 4 (BGP-4)", RFC 4271,
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              Protocol?", RFC 5218, DOI 10.17487/RFC5218, July 2008,
              <https://www.rfc-editor.org/info/rfc5218>.

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              DOI 10.17487/RFC8890, August 2020,
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              Wood, "Oblivious DNS over HTTPS", RFC 9230,
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              STD 7, RFC 9293, DOI 10.17487/RFC9293, August 2022,
              <https://www.rfc-editor.org/info/rfc9293>.

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              Intermediaries in Internet Protocols", Work in Progress,
              Internet-Draft, draft-thomson-tmi-04, 8 September 2022,
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              04>.

Acknowledgements

   This document was born out of early discussions with Brian Trammell
   during our shared time on the Internet Architecture Board.

   Special thanks to Geoff Huston and Milton Mueller for their well-
   considered, thoughtful, and helpful reviews.

   Thanks to Jari Arkko, Kristin Berdan, Richard Clayton, Cory Doctorow,
   Christian Huitema, Eliot Lear, John Levine, Tommy Pauly, and Martin
   Thomson for their comments and suggestions.  Likewise, the arch-
   discuss@ietf.org (mailto:arch-discuss@ietf.org) mailing list and
   Decentralized Internet Infrastructure Research Group provided
   valuable discussion and feedback.

   No large language models were used in the production of this
   document.

Author's Address

   Mark Nottingham
   Prahran
   Australia
   Email: mnot@mnot.net
   URI:   https://www.mnot.net/