Internet DRAFT - draft-iab-path-signals-collaboration
draft-iab-path-signals-collaboration
Network Working Group J. Arkko
Internet-Draft Ericsson
Intended status: Informational T. Hardie
Expires: August 5, 2023 Cisco
T. Pauly
Apple
M. Kuehlewind
Ericsson
February 01, 2023
Considerations on Application - Network Collaboration Using Path Signals
draft-iab-path-signals-collaboration-03
Abstract
This document discusses principles for designing mechanisms that use
or provide path signals, and calls for standards action in specific
valuable cases. RFC 8558 describes path signals as messages to or
from on-path elements, and points out that visible information will
be used whether it is intended as a signal or not. The principles in
this document are intended as guidance for the design of explicit
path signals, which are encouraged to be authenticated and include a
minimal set of parties to minimize information sharing. These
principles can be achieved through mechanisms like encryption of
information and establishing trust relationships between entities on
a path.
Status of This Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute
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Drafts is at http://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress."
This Internet-Draft will expire on August 5, 2023.
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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
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Principles . . . . . . . . . . . . . . . . . . . . . . . . . 6
2.1. Intentional Distribution . . . . . . . . . . . . . . . . 7
2.2. Control of the Distribution of Information . . . . . . . 7
2.3. Protecting Information and Authentication . . . . . . . . 8
2.4. Minimize Information . . . . . . . . . . . . . . . . . . 9
2.5. Limiting Impact of Information . . . . . . . . . . . . . 10
2.6. Minimum Set of Entities . . . . . . . . . . . . . . . . . 11
2.7. Carrying Information . . . . . . . . . . . . . . . . . . 11
3. Further Work . . . . . . . . . . . . . . . . . . . . . . . . 12
4. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 14
5. Informative References . . . . . . . . . . . . . . . . . . . 14
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 17
1. Introduction
[RFC8558] defines the term "path signals" as signals to or from on-
path elements. Today path signals are often implicit, e.g. derived
from cleartext end-to-end information by e.g. examining transport
protocols. For instance, on-path elements use various fields of the
TCP header [RFC0793] to derive information about end-to-end latency
as well as congestion. These techniques have evolved because the
information was available and its use required no coordination with
anyone. This made such techniques more easily deployable than
alternative, potentially more explicit or cooperative, approaches.
However, this also means that applications and networks have often
evolved their interaction without comprehensive design for how this
interaction should happen or which (minimal) information would be
needed for a certain function. This has led to a situation where
simply information that happens to be easily available is used
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instead the information that would be actually needed. As such that
information may be incomplete, incorrect, or only indirectly
representative of the information that is actually needed. In
addition, dependencies on information and mechanisms that were
designed for a different function limits the evolvability of the
protocols in question.
In summary, such unplanned interactions end up having several
negative effects:
o Ossifying protocols by introducing dependencies to unintended
parties that may not be updating, such as how middleboxes have
limited the use of TCP options
o Creating systemic incentives against deploying more secure or
otherwise updated versions of protocols
o Basing network behaviour on information that may be incomplete or
incorrect
o Creating a model where network entities expect to be able to use
rich information about sessions passing through
For instance, features such as DNS resolution or TLS setup have been
used beyond their original intent, such as in name-based filtering.
MAC addresses have been used for access control, captive portals have
been used to take over cleartext HTTP sessions, and so on. (This
document is not about whether those practices are good or bad, it is
simply stating a fact that the features were used beyond their
original intent.)
Many protocol mechanisms throughout the stack fall into one of two
categories: authenticated and private communication that is only
visible to a very limited set of parties, often one on each "end";
and unauthenticated public communication that is also visible to all
network elements on a path.
Exposed information encourages pervasive monitoring, which is
described in RFC 7258 [RFC7258], and may also be used for commercial
purposes, or form a basis for filtering that the applications or
users do not desire. But a lack of all path signalling, on the other
hand, may limit network management, debugging, or the ability for
networks to optimize their services. There are many cases where
elements on the network path can provide beneficial services, but
only if they can coordinate with the endpoints. It also affects the
ability of service providers and others to observe why problems occur
[RFC9075].
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As such, this situation is sometimes cast as an adversarial tradeoff
between privacy and the ability for the network path to provide
intended functions. However, this is perhaps an unnecessarily
polarized characterization as a zero-sum situation. Not all
information passing implies loss of privacy. For instance,
performance information or preferences do not require disclosing the
content being accessed, the user identity, or the application in use.
Similarly, network congestion status information does not have to
reveal network topology or the status of other users, and so on.
Increased deployment of encryption is changing this situation.
Encryption provides tools for controlling information access and
protects against ossification by avoiding unintended dependencies and
requiring active maintenance. The increased deployment of encryption
provides an opportunity to reconsider parts of Internet architecture
that have used implicit derivation of input signals for on-path
functions rather than explicit signalling, as recommended by RFC 8558
[RFC8558].
For instance, QUIC replaces TCP for various applications and ensures
end-to-end signals are only accessible by the endpoints, ensuring
evolvability [RFC9000]. QUIC does expose information dedicated for
on-path elements to consume by using explicit signals for specific
use cases, such as the Spin bit for latency measurements or
connection ID that can be used by load balancers
[I-D.ietf-quic-manageability]. This information is accessible by all
on-path devices but information is limited to only those use cases.
Each new use case requires additional action. This points to one way
to resolve the adversity: the careful design of what information is
passed.
Another extreme is to employ explicit trust and coordination between
specific entities, endpoints as well as network path elements. VPNs
are a good example of a case where there is an explicit
authentication and negotiation with a network path element that is
used to gain access to specific resources. Authentication and trust
must be considered in both directions: how endpoints trust and
authenticate signals from network path elements, and how network path
elements trust and authenticate signals from endpoints.
The goal of improving privacy and trust on the Internet does not
necessarily need to remove the ability for network elements to
perform beneficial functions. We should instead improve the way that
these functions are achieved and design new ways to support explicit
collaboration where it is seen as beneficial. As such our goals
should be:
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o To ensure that information is distributed intentionally, not
accidentally;
o to understand the privacy and other implications of any
distributed information;
o to ensure that the information distribution is limited to the
intended parties; and
o to gate the distribution of information on the participation of
the relevant parties.
These goals for exposure and distribution apply equally to senders,
receivers, and path elements.
Going forward, new standards work in the IETF needs to focus on
addressing this gap by providing better alternatives and mechanisms
for building functions that require some collaboration between
endpoints and path elements.
We can establish some basic questions that any new network functions
should consider:
o Which entities must consent to the information exchange?
o What is the minimum information each entity in this set needs?
o What is the effect that new signals should have?
o What is the minimum set of entities that need to be involved?
o What is the right mechanism and needed level of trust to convey
this kind of information?
If we look ways network functions are achieved today, we find that
many if not most of them fall short the standard set up by the
questions above. Too often, they send unnecessary information or
fail to limit the scope of distribution or providing any negotiation
or consent.
Designing explicit signals between applications and network elements,
and ensuring that all information is appropriately protected, enables
information exchange in both directions that is important for
improving the quality of experience and network management. The
clean separation provided by explicit signals is also more conducive
to protocol evolvability.
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Beyond the recommendation in [RFC8558], the IAB has provided further
guidance on protocol design. Among other documents, [RFC5218]
provides general advice on incremental deployability based on an
analysis of successes and failures and [RFC6709] discusses protocol
extensibility. The Internet Technology Adoption and Transition
(ITAT) workshop report [RFC7305] is also recommended reading on this
same general topic. [RFC9049], an IRTF document, provides a
catalogue of past issues to avoid and discusses incentives for
adoption of path signals such as the need for outperforming end-to-
end mechanisms or considering per-connection state.
This draft discusses different approaches for explicit collaboration
and provides guidance on architectural principles to design new
mechanisms. Section 2 discusses principles that good design can
follow. This section also provides some examples and explanation of
situations that not following the principles can lead to. Section 3
points to topics that need more to be looked at more carefully before
any guidance can be given.
2. Principles
This section provides architecture-level principles for protocol
designers and recommends models to apply for network collaboration
and signalling.
While RFC 8558 [RFC8558] focused specifically on communication to
"on-path elements", the principles described in this document apply
potentially to
o on-path signalling, in either direction
o signalling with other elements in the network that are not
directly on-path, but still influence end-to-end connections.
An example of on-path signalling is communication between an endpoint
and a router on a network path. An example of signalling with
another network element is communication between an endpoint and a
network-assigned DNS server, firewall controller, or captive portal
API server. Note that these communications are conceptually
independent of the base flow, even if they share a packet; they are
from and to other parties, rather than creating a multiparty
communication.
Taken together, these principles focus on the inherent privacy and
security concerns of sharing information between endpoints and
network elements, emphasizing that careful scrutiny and a high bar of
consent and trust need to be applied. Given the known threat of
pervasive monitoring, the application of these principles is critical
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to ensuring that the use of path signals does not create a
disproportionate opportunity for observers to extract new data from
flows.
2.1. Intentional Distribution
This guideline is best expressed in [RFC8558]:
"Fundamentally, this document recommends that implicit signals should
be avoided and that an implicit signal should be replaced with an
explicit signal only when the signal's originator intends that it be
used by the network elements on the path. For many flows, this may
result in the signal being absent but allows it to be present when
needed."
The goal is that any information should be provided knowingly, for a
specific purpose, sent in signals designed for that purpose, and that
any use of information should be done within that purpose. And that
an analysis of the security and privacy implications of the specific
purpose and associated information is needed.
This guideline applies in the network element to application
direction as well: a network element should not unintentionally leak
information. While this document makes recommendations that are
applicable to many different situations, it is important to note that
the above call for careful analysis is key. Different types of
information, different applications, and different directions of
communication influence the the analysis, and can lead to very
different conclusions about what information can be shared or with
whom. For instance, it is easy to find examples of information that
applications should not share with network elements (e.g., content of
communications) or network elements should not share with
applications (e.g., detailed user location in a wireless network).
But, equally, information about other things such as the onset of
congestion should be possible to share, and can be beneficial
information to all parties.
Intentional distribution is a precondition for explicit collaboration
enabling each entity to have the highest posssible level of control
about what information to share.
2.2. Control of the Distribution of Information
Explicit signals are not enough. The entities also need to agree to
exchange the information. Trust and mutual agreement between the
involved entities must determine the distribution of information, in
order to give adequate control to each entity over the collaboration
or information sharing. This can be achieved as discussed below.
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The sender needs to decide that it is willing to send information to
a specific entity or set of entities. Any passing of information or
request for an action needs to be explicit, and use signalling
mechanisms that are designed for the purpose. Merely sending a
particular kind of packet to a destination should not be interpreted
as an implicit agreement.
At the same time, the recipient of information or the target of a
request should have the option to agree or deny to receiving the
information. It should not be burdened with extra processing if it
does not have willingness or a need to do so. This happens naturally
in most protocol designs, but has been a problem for some cases where
"slow path" packet processing is required or implied, and the
recipient or router is not willing to handle this. Performance
impacts like this are best avoided, however.
In any case, all involved entities must be identified and potentially
authenticated if trust is required as a prerequisite to share certain
information.
Many Internet communications are not performed on behalf of the
applications, but are ultimately made on behalf of users. However,
not all information that may be shared directly relates to user
actions or other sensitive data. All information shared must be
evaluated carefully to identify potential privacy implications for
users. Information that directly relates to the user should not be
shared without the user's consent. It should be noted that the
interests of the user and other parties, such as the application
developer, may not always coincide; some applications may wish to
collect more information about the user than the user would like. As
discussed in [RFC8890], from an IETF point view, the interests of the
user should be prioritized over those of the application developer.
The general issue of how to achieve a balance of control between the
actual user and an application representing an user's interest is out
of scope for this document.
2.3. Protecting Information and Authentication
Some simple forms of information often exist in cleartext form, e.g,
ECN bits from routers are generally not authenticated or integrity
protected. This is possible when the information exchanges do not
carry any significantly sensitive information from the parties.
Often these kind of interactions are also advisory in their nature
(see also section Section 2.5).
In other cases it may be necessary to establish a secure signalling
channel for communication with a specific other party, e.g., between
a network element and an application. This channel may need to be
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authenticated, integrity protected and confidential. This is
necessary, for instance, if the particular information or request
needs to be shared in confidence only with a particular, trusted
network element or endpoint, or there's a danger of an attack where
someone else may forge messages that could endanger the
communication.
Authenticated integrity protections on signalled data can help ensure
that data received in a signal has not been modified by other
parties. Still, both network elements and endpoints need to be
careful in processing or responding to any signal. Whether through
bugs or attacks, the content of path signals can lead to unexpected
behaviors or security vulnerabilities if not properly handled. As a
result, the advice in Section 2.5 still applies even in situations
where there's a secure channel for sending information.
However, it is important to note that authentication does not equal
trust. Whether a communication is with an application server or
network element that can be shown to be associated with a particular
domain name, it does not follow that information about the user can
be safely sent to it.
In some cases, the ability of a party to show that it is on the path
can be beneficial. For instance, an ICMP error that refers to a
valid flow may be more trustworthy than any ICMP error claiming to
come from an address.
Other cases may require more substantial assurances. For instance, a
specific trust arrangement may be established between a particular
network and application. Or technologies such as confidential
computing can be applied to provide an assurance that information
processed by a party is handled in an appropriate manner.
2.4. Minimize Information
Each party should provide only the information that is needed for the
other parties to perform the task for which collaboration is desired,
and no more. This applies to information sent by an application
about itself, information sent about users, or information sent by
the network. This also applies to any information related to flow
identification.
An architecture can follow the guideline from [RFC8558] in using
explicit signals, but still fail to differentiate properly between
information that should be kept private and information that should
be shared. [RFC6973] also outlines this principle of data
minimization as mitigation technique to protect privacy and provides
further guidance.
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In looking at what information can or cannot easily be passed, we
need to consider both, information from the network to the
application and from the application to the network.
For the application to the network direction, user-identifying
information can be problematic for privacy and tracking reasons.
Similarly, application identity can be problematic, if it might form
the basis for prioritization or discrimination that the application
provider may not wish to happen.
On the other hand, as noted above, information about general classes
of applications may be desirable to be given by application
providers, if it enables prioritization that would improve service,
e.g., differentiation between interactive and non-interactive
services.
For the network to application direction there is similarly sensitive
information, such as the precise location of the user. On the other
hand, various generic network conditions, predictive bandwidth and
latency capabilities, and so on might be attractive information that
applications can use to determine, for instance, optimal strategies
for changing codecs. However, information given by the network about
load conditions and so on should not form a mechanism to provide a
side-channel into what other users are doing.
While information needs to be specific and provided on a per-need
basis, it is often beneficial to provide declarative information
that, for instance, expresses application needs than makes specific
requests for action.
2.5. Limiting Impact of Information
Information shared between a network element and an endpoint of a
connection needs to have a limited impact on the behavior of both
endpoints and network elements. Any action that an endpoint or
network element takes based on a path signal needs to be considered
appropriately based on the level of authentication and trust that has
been established, and be scoped to a specific network path.
For example, an ICMP signal from a network element to an endpoint can
be used to influence future behavior on that particular network path
(such as changing the effective packet size or closing a path-
specific connection), but should not be able to cause a multipath or
migration-capable transport connection to close.
In many cases, path signals can be considered to be advisory
information, with the effect of optimizing or adjusting the behavior
of connections on a specific path. In the case of a firewall
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blocking connectivity to a given host, endpoints should only
interpret that as the host being unavailable on that particular path;
this is in contrast to an end-to-end authenticated signal, such as a
DNSSEC-authenticated denial of existence [RFC7129].
2.6. Minimum Set of Entities
It is recommended that a design identifies the minimum number of
entities needed to share a specific signal required for an identified
function.
Often this will be a very limited set, such as when an application
only needs to provide a signal to its peer at the other end of the
connection or a host needs to contact a specific VPN gateway. In
other cases a broader set is needed, such as when explicit or
implicit signals from a potentially unknown set of multiple routers
along the path inform the endpoints about congestion.
While it is tempting to consider removing these limitations in the
context of closed, private networks, each interaction is still best
considered separately, rather than simply allowing all information
exchanges within the closed network. Even in a closed network with
carefully managed elements there may be compromised components, as
evidenced in the most extreme way by the Stuxnet worm that operated
in an airgapped network. Most "closed" networks have at least some
needs and means to access the rest of the Internet, and should not be
modeled as if they had an impenetrable security barrier.
2.7. Carrying Information
There is a distinction between what information is sent and how it is
sent. The actually sent information may be limited, while the
mechanisms for sending or requesting information can be capable of
sharing much more.
There is a tradeoff here between flexibility and ensuring the
minimality of information in the future. The concern is that a fully
generic data sharing approach between different layers and parties
could potentially be misused, e.g., by making the availability of
some information a requirement for passing through a network, such as
making it mandatory to identify specific applications or users. This
is undesirable.
This document recommends that signalling mechanisms that send
information are built to specifically support sending the necessary,
minimal set of information (see Section 2.4) and no more. As
previously noted, flow-identifying information is a path signal in
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itself, and as such provisioning of flow identifiers also requires
protocol specific analysis.
Further, such mechanisms also need have an ability for establishing
an agreement (see Section 2.2) and to establish sufficient trust to
pass the information (see Section 2.3).
3. Further Work
This is a developing field, and it is expected that our understanding
will continue to grow. One recent change is much higher use of
encryption at different protocol layers. This obviously impacts the
field greatly, by removing the ability to use most implicit signals.
But it may also provide new tools for secure collaboration, and force
a rethinking of how collaboration should be performed.
While there are some examples of modern, well-designed collaboration
mechanisms, the list of examples is not long. Clearly more work is
needed, if we wish to realize the potential benefits of collaboration
in further cases. This requires a mindset change, a migration away
from using implicit signals. And of course, we need to choose such
cases where the collaboration can be performed safely, is not a
privacy concern, and the incentives of the relevant parties are
aligned. It should also be noted that many complex cases would
require significant developments in order to become feasible.
Some of the most difficult areas are listed below. Research on
these topics would be welcome. Note that the topics include both
those dealing directly with on-path network element collaboration, as
well as some adjacent issues that would influence such collaboration.
o Some forms of collaboration may depend on business arrangements,
which may or may not be easy to put in place. For instance, some
quality-of-service mechanisms involve an expectation of paying for
a service. This is possible and has been successful within
individual domains, e.g., users can pay for higher data rates or
data caps in their ISP networks. However, it is a business-wise
much harder proposition for end-to-end connections across multiple
administrative domains [Claffy2015] [RFC9049].
o Secure communications with path elements is needed as discussed in
Section 2.3. Finding practical ways for this has been difficult,
both from the mechanics and scalability point view. And also
because there is no easy way to find out which parties to trust or
what trust roots would be appropriate. Some application-network
element interaction designs have focused on information (such as
ECN bits) that is distributed openly within a path, but there are
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limited examples of designs with secure information exchange with
specific network elements or endpoints.
o The use of path signals for reducing the effects of denial-of-
service attacks, e.g., perhaps modern forms of "source quench"
designs could be developed. The difficulty is finding a solution
that would be both effective against attacks and would not enable
third parties from slowing down or censoring someone else's
commmunication.
o Ways of protecting information when held by network elements or
servers, beyond communications security. For instance, host
applications commonly share sensitive information about the user's
actions with other parties, starting from basic data such as
domain names learned by DNS infrastructure or source and
destination addresses and protocol header information learned by
all routers on the path, to detailed end user identity and other
information learned by the servers. Some solutions are starting
to exist for this but are not widely deployed, at least not today
[Oblivious] [PDoT] [I-D.arkko-dns-confidential]
[I-D.thomson-http-oblivious]. These solutions address also very
specific parts of the issue, and more work remains.
o Sharing information from networks to applications. There are some
working examples of this, e.g., ECN. A few other proposals have
been made (see, e.g., [I-D.flinck-mobile-throughput-guidance]),
but very few of those have seen deployment.
o Sharing information from applications to networks. There are a
few more working examples of this (see Section 1). However,
numerous proposals have been made in this space, but most of them
have not progressed through standards or been deployed, for a
variety of reasons [RFC9049]. Several current or recent proposals
exist, however, such as [I-D.yiakoumis-network-tokens].
o Data privacy regimes generally deal with more issues than merely
whether some information is shared with another party or not. For
instance, there may be rules regarding how long information can be
stored or what purpose information may be used for. Similar
issues may also be applicable to the kind of information sharing
discussed in this document.
o The present work has focused on the technical aspects of making
collabration safe and mutually beneficial, but of course,
deployments need to take into account various regulatory and other
policy matters. These include privacy regulation, competitive
issues & network neutrality aspects, and so on.
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4. Acknowledgments
The authors would like to thank everyone at the IETF, the IAB, and
our day jobs for interesting thoughts and proposals in this space.
Fragments of this document were also in
[I-D.per-app-networking-considerations] and
[I-D.arkko-path-signals-information] that were published earlier. We
would also like to acknowledge [I-D.trammell-stackevo-explicit-coop]
for presenting similar thoughts. Finally, the authors would like to
thank Adrian Farrell, Toerless Eckert, Martin Thomson, Mark
Nottingham, Luis M. Contreras, Watson Ladd, Vittorio Bertola, Andrew
Campling, Eliot Lear, Spencer Dawkins, Christian Huitema, David
Schinazi, Cullen Jennings, Mallory Knodel, Zhenbin Li, Chris Box, and
Jeffrey Haas for useful feedback on this topic and this draft.
5. Informative References
[Claffy2015]
kc Claffy, . and D. Clark, "Adding Enhanced Services to
the Internet: Lessons from History", TPRC 43: The 43rd
Research Conference on Communication, Information and
Internet Policy Paper , April 2015.
[I-D.arkko-dns-confidential]
Arkko, J. and J. Novotny, "Privacy Improvements for DNS
Resolution with Confidential Computing", draft-arkko-dns-
confidential-02 (work in progress), July 2021,
<https://www.ietf.org/archive/id/draft-arkko-dns-
confidential-02.txt>.
[I-D.arkko-path-signals-information]
Arkko, J., "Considerations on Information Passed between
Networks and Applications", draft-arkko-path-signals-
information-00 (work in progress), February 2021,
<https://www.ietf.org/archive/id/draft-arkko-path-signals-
information-00.txt>.
[I-D.flinck-mobile-throughput-guidance]
Jain, A., Terzis, A., Flinck, H., Sprecher, N.,
Arunachalam, S., Smith, K., Devarapalli, V., and R. Yanai,
"Mobile Throughput Guidance Inband Signaling Protocol",
draft-flinck-mobile-throughput-guidance-04 (work in
progress), March 2017, <https://www.ietf.org/archive/id/
draft-flinck-mobile-throughput-guidance-04.txt>.
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[I-D.ietf-quic-manageability]
Kuehlewind, M. and B. Trammell, "Manageability of the QUIC
Transport Protocol", draft-ietf-quic-manageability-18
(work in progress), July 2022,
<https://www.ietf.org/archive/id/draft-ietf-quic-
manageability-18.txt>.
[I-D.per-app-networking-considerations]
Colitti, L. and T. Pauly, "Per-Application Networking
Considerations", draft-per-app-networking-
considerations-00 (work in progress), November 2020,
<https://www.ietf.org/archive/id/draft-per-app-networking-
considerations-00.txt>.
[I-D.thomson-http-oblivious]
Thomson, M. and C. Wood, "Oblivious HTTP", draft-thomson-
http-oblivious-02 (work in progress), August 2021,
<https://www.ietf.org/archive/id/draft-thomson-http-
oblivious-02.txt>.
[I-D.trammell-stackevo-explicit-coop]
Trammell, B., "Architectural Considerations for Transport
Evolution with Explicit Path Cooperation", draft-trammell-
stackevo-explicit-coop-00 (work in progress), September
2015, <https://www.ietf.org/archive/id/draft-trammell-
stackevo-explicit-coop-00.txt>.
[I-D.yiakoumis-network-tokens]
Yiakoumis, Y., McKeown, N., and F. Sorensen, "Network
Tokens", draft-yiakoumis-network-tokens-02 (work in
progress), December 2020,
<https://www.ietf.org/archive/id/draft-yiakoumis-network-
tokens-02.txt>.
[Oblivious]
Schmitt, P., "Oblivious DNS: Practical privacy for DNS
queries", Proceedings on Privacy Enhancing Technologies
2019.2: 228-244 , 2019.
[PDoT] Nakatsuka, Y., Paverd, A., and G. Tsudik, "PDoT: Private
DNS-over-TLS with TEE Support", Digit. Threat.: Res.
Pract., Vol. 2, No. 1, Article 3, https://dl.acm.org/doi/
fullHtml/10.1145/3431171 , February 2021.
[RFC0793] Postel, J., "Transmission Control Protocol", RFC 793,
DOI 10.17487/RFC0793, September 1981, <https://www.rfc-
editor.org/info/rfc793>.
Arkko, et al. Expires August 5, 2023 [Page 15]
Internet-Draft Path Signals Collab February 2023
[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>.
[RFC6709] Carpenter, B., Aboba, B., Ed., and S. Cheshire, "Design
Considerations for Protocol Extensions", RFC 6709,
DOI 10.17487/RFC6709, September 2012, <https://www.rfc-
editor.org/info/rfc6709>.
[RFC6973] Cooper, A., Tschofenig, H., Aboba, B., Peterson, J.,
Morris, J., Hansen, M., and R. Smith, "Privacy
Considerations for Internet Protocols", RFC 6973,
DOI 10.17487/RFC6973, July 2013, <https://www.rfc-
editor.org/info/rfc6973>.
[RFC7129] Gieben, R. and W. Mekking, "Authenticated Denial of
Existence in the DNS", RFC 7129, DOI 10.17487/RFC7129,
February 2014, <https://www.rfc-editor.org/info/rfc7129>.
[RFC7258] Farrell, S. and H. Tschofenig, "Pervasive Monitoring Is an
Attack", BCP 188, RFC 7258, DOI 10.17487/RFC7258, May
2014, <https://www.rfc-editor.org/info/rfc7258>.
[RFC7305] Lear, E., Ed., "Report from the IAB Workshop on Internet
Technology Adoption and Transition (ITAT)", RFC 7305,
DOI 10.17487/RFC7305, July 2014, <https://www.rfc-
editor.org/info/rfc7305>.
[RFC8558] Hardie, T., Ed., "Transport Protocol Path Signals",
RFC 8558, DOI 10.17487/RFC8558, April 2019,
<https://www.rfc-editor.org/info/rfc8558>.
[RFC8890] Nottingham, M., "The Internet is for End Users", RFC 8890,
DOI 10.17487/RFC8890, August 2020, <https://www.rfc-
editor.org/info/rfc8890>.
[RFC9000] Iyengar, J., Ed. and M. Thomson, Ed., "QUIC: A UDP-Based
Multiplexed and Secure Transport", RFC 9000,
DOI 10.17487/RFC9000, May 2021, <https://www.rfc-
editor.org/info/rfc9000>.
[RFC9049] Dawkins, S., Ed., "Path Aware Networking: Obstacles to
Deployment (A Bestiary of Roads Not Taken)", RFC 9049,
DOI 10.17487/RFC9049, June 2021, <https://www.rfc-
editor.org/info/rfc9049>.
Arkko, et al. Expires August 5, 2023 [Page 16]
Internet-Draft Path Signals Collab February 2023
[RFC9075] Arkko, J., Farrell, S., Kuehlewind, M., and C. Perkins,
"Report from the IAB COVID-19 Network Impacts Workshop
2020", RFC 9075, DOI 10.17487/RFC9075, July 2021,
<https://www.rfc-editor.org/info/rfc9075>.
Authors' Addresses
Jari Arkko
Ericsson
Email: jari.arkko@ericsson.com
Ted Hardie
Cisco
Email: ted.ietf@gmail.com
Tommy Pauly
Apple
Email: tpauly@apple.com
Mirja Kuehlewind
Ericsson
Email: mirja.kuehlewind@ericsson.com
Arkko, et al. Expires August 5, 2023 [Page 17]
