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 © 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 publication of this document. Please review these documents carefully, as they describe your rights and restrictions with respect 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

[Abrahamson]

              Abrahamson, Z., "Essential Data", Yale Law Journal, Vol.
              124, No. 3, December 2014,
              <https://www.yalelawjournal.org/comment/essential-data>.

[ACTIVITYSTREAMS]

              Prodromou, E., Ed. and J. Snell, Ed., "Activity Streams
              2.0", W3C Recommendation, 23 May 2017,
              <https://www.w3.org/TR/2017/REC-activitystreams-core-
              20170523/>.  Latest version available at
              <https://www.w3.org/TR/ activitystreams-core/>.
   
   [Aligia]   Aligia, P. and V. Tarko, "Polycentricity: From Polanyi to
              Ostrom, and Beyond", Governance: An International Journal
              of Policy, Administration, and Institutions, Vol. 25, No.
              2, p. 237, DOI 10.1111/j.1468-0491.2011.01550.x, April
              2012, <https://onlinelibrary.wiley.com/doi/abs/10.1111/
              j.1468-0491.2011.01550.x>.
   
   [Bacchi]   Bacchi, C., "Introducing the 'What's the Problem
              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>.
   
   [Baran]    Baran, P., "On Distributed Communications: Introduction to
              Distributed Communications Networks", DOI 10.7249/RM3420,
              1964, <https://www.rand.org/pubs/research_memoranda/
              RM3420.html>.
   
   [BCP95]    Alvestrand, H., "A Mission Statement for the IETF",
              BCP 95, RFC 3935, October 2004.

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

   [Bodo]     Bodó, B., Brekke, J. K., and J.-H. Hoepman,
              "Decentralization: a multidisciplinary perspective",
              Internet Policy Review, Vol. 10, No. 2,
              DOI 10.14763/2021.2.1563, June 2021,
              <https://policyreview.info/concepts/decentralisation>.
   
   [Chaum]    Chaum, D., "Untraceable electronic mail, return addresses,
              and digital pseudonyms", Communications of the ACM, Vol.
              24, No. 2, DOI 10.1145/358549.358563, February 1981,
              <https://dl.acm.org/doi/10.1145/358549.358563>.

[Christensen]

              Christensen, C., "The Law of Conservation of Attractive
              Profits", Harvard Business Review, "Breakthrough Ideas for
              2004", February 2004.
   
   [Demsetz]  Demsetz, H., "Industry Structure, Market Rivalry, and
              Public Policy", Journal of Law and Economics, Vol. 16, No.
              1, April 1973, <https://www.jstor.org/stable/724822>.
   
   [DMA]      The European Parliament and the Council of the European
              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>.
   
   [Doctorow] Doctorow, C., "Adversarial Interoperability", October
              2019, <https://www.eff.org/deeplinks/2019/10/adversarial-
              interoperability>.
   
   [ETHEREUM] Ethereum, "The Merge", February 2023,
              <https://ethereum.org/en/roadmap/merge/>.

[FarrellH] Farrell, H. and A. Newman, "Weaponized Interdependence:

How Global Economic Networks Shape State Coercion", International Security, Vol. 44, No. 1, p. 42, DOI 10.1162/ISEC_a_00351, July 2019, <https://doi.org/10.1162/ISEC_a_00351>.

   [FarrellJ] Farrell, J. and C. Shapiro, "Dynamic Competition with
              Switching Costs", UC Berkeley Department of Economics
              Working Paper 8865, DOI 10.2307/2555402, January 1988,
              <https://doi.org/10.2307/2555402>.
   
   [Fletcher] Fletcher, A., "The Role of Behavioural Economics in
              Competition Policy", DOI 10.2139/ssrn.4389681, March 2023,
              <https://doi.org/10.2139/ssrn.4389681>.
   
   [Freeman]  Freeman, J., "The Tyranny of Structurelessness", Berkeley
              Journal of Sociology, Vol. 17, 1972,
              <https://www.jstor.org/stable/41035187>.

[Holzbauer]

              Holzbauer, F., Ullrich, J., Lindorfer, M., and T. Fiebig,
              "Not that Simple: Email Delivery in the 21st Century",
              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?",
              DOI 10.1145/3419394.3423664, October 2020,
              <https://dl.acm.org/doi/pdf/10.1145/3419394.3423664>.
   
   [Komaitis] Komaitis, K., "Regulators Seem to Think That Facebook Is
              the Internet", August 2021,
              <https://slate.com/technology/2021/08/facebook-internet-
              regulation.html>.
   
   [Lessig]   Lessig, L., "The New Chicago School", Journal of Legal
              Studies, Vol. 27, DOI 10.1086/468039, June 1998,
              <https://www.journals.uchicago.edu/doi/10.1086/468039>.
   
   [Madison]  Madison, J., "The Structure of the Government Must Furnish
              the Proper Checks and Balances Between the Different
              Departments", The Federalist Papers, No. 51, February
              1788.
   
   [Makarov]  Makarov, I. and A. Schoar, "Blockchain Analysis of the
              Bitcoin Market", National Bureau of Economic Research,
              Working Paper 29396, DOI 10.3386/w29396, October 2021,
              <https://www.nber.org/papers/w29396>.

[Marlinspike]

              Marlinspike, M., "Reflections: The ecosystem is moving",
              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,
              October 2020,
              <https://dl.acm.org/doi/abs/10.1145/3419394.3423625>.
   
   [Musiani]  Musiani, F., "Alternative Technologies as Alternative
              Institutions: The Case of the Domain Name System", The
              Turn to Infrastructure in Internet Governance,
              DOI 10.1057/9781137483591_4, 2016,
              <https://link.springer.com/
              chapter/10.1057/9781137483591_4>.

[Palladino]

              Palladino, N. and M. Santaniello, "Legitimacy, Power, and
              Inequalities in the Multistakeholder Internet Governance",
              DOI 10.1007/978-3-030-56131-4, November 2020,
              <https://link.springer.com/
              book/10.1007/978-3-030-56131-4>.
   
   [PHONE]    Skrzycki, C. and J. Burgess, "Computer Failure Paralyzes
              Region's Phone Service", June 1991,
              <https://www.washingtonpost.com/archive/
              politics/1991/06/27/computer-failure-paralyzes-regions-
              phone-service/0db94ac7-89f0-446e-ba33-c126c751b251/>.
   
   [RFC2026]  Bradner, S., "The Internet Standards Process -- Revision
              3", BCP 9, RFC 2026, DOI 10.17487/RFC2026, October 1996,
              <https://www.rfc-editor.org/info/rfc2026>.
   
   [RFC4271]  Rekhter, Y., Ed., Li, T., Ed., and S. Hares, Ed., "A
              Border Gateway Protocol 4 (BGP-4)", RFC 4271,
              DOI 10.17487/RFC4271, January 2006,
              <https://www.rfc-editor.org/info/rfc4271>.
   
   [RFC5218]  Thaler, D. and B. Aboba, "What Makes for a Successful
              Protocol?", RFC 5218, DOI 10.17487/RFC5218, July 2008,
              <https://www.rfc-editor.org/info/rfc5218>.
   
   [RFC5321]  Klensin, J., "Simple Mail Transfer Protocol", RFC 5321,
              DOI 10.17487/RFC5321, October 2008,
              <https://www.rfc-editor.org/info/rfc5321>.
   
   [RFC6120]  Saint-Andre, P., "Extensible Messaging and Presence
              Protocol (XMPP): Core", RFC 6120, DOI 10.17487/RFC6120,
              March 2011, <https://www.rfc-editor.org/info/rfc6120>.
   
   [RFC791]   Postel, J., "Internet Protocol", STD 5, RFC 791,
              DOI 10.17487/RFC0791, September 1981,
              <https://www.rfc-editor.org/info/rfc791>.
   
   [RFC8890]  Nottingham, M., "The Internet is for End Users", RFC 8890,
              DOI 10.17487/RFC8890, August 2020,
              <https://www.rfc-editor.org/info/rfc8890>.
   
   [RFC9230]  Kinnear, E., McManus, P., Pauly, T., Verma, T., and C.A.
              Wood, "Oblivious DNS over HTTPS", RFC 9230,
              DOI 10.17487/RFC9230, June 2022,
              <https://www.rfc-editor.org/info/rfc9230>.
   
   [RFC9293]  Eddy, W., Ed., "Transmission Control Protocol (TCP)",
              STD 7, RFC 9293, DOI 10.17487/RFC9293, August 2022,
              <https://www.rfc-editor.org/info/rfc9293>.

[Schneider1]

              Schneider, N., "What to do once you admit that
              decentralizing everything never seems to work", Hacker
              Noon, September 2019, <https://hackernoon.com/
              decentralizing-everything-never-seems-to-work-
              2bb0461bd168>.

[Schneider2]

              Schneider, N., "Decentralization: An Incomplete Ambition",
              Journal of Cultural Economy, Vol. 12, No. 4,
              DOI 10.31219/osf.io/m7wyj, April 2019,
              <https://osf.io/m7wyj/>.
   
   [SOAP]     Mitra, N., Ed. and Y. Lafon, Ed., "SOAP Version 1.2 Part
              0: Primer (Second Edition)", W3C Recommendation, 27 April
              2007,
              <https://www.w3.org/TR/2007/REC-soap12-part0-20070427/>.
              Latest version available at <https://www.w3.org/TR/
              soap12-part0/>.
   
   [Spulber]  Spulber, D., "Solving The Circular Conundrum:
              Communication and Coordination in Two-Sided Markets",
              Northwestern University Law Review, Vol. 104, No. 2,
              October 2009, <https://wwws.law.northwestern.edu/research-
              faculty/clbe/workingpapers/documents/
              spulber_circularconundrum.pdf>.

[THOMSON-TMI]

              Thomson, M., "Principles for the Involvement of
              Intermediaries in Internet Protocols", Work in Progress,
              Internet-Draft, draft-thomson-tmi-04, 8 September 2022,
              <https://datatracker.ietf.org/doc/html/draft-thomson-tmi-
              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/