Internet DRAFT - draft-iab-marnew-report
draft-iab-marnew-report
Internet Architecture Board N. Rooney
Internet-Draft GSMA
Intended status: Informational S. Dawkins, Ed.
Expires: November 26, 2018 Wonder Hamster
May 25, 2018
IAB Workshop on Managing Radio Networks in an Encrypted World (MaRNEW)
Report
draft-iab-marnew-report-02
Abstract
The Internet Architecture Board (IAB) and GSM Association (GSMA) held
a joint workshop on "Managing Radio Networks in an Encrypted World"
(MaRNEW), on September 24-25, 2015. This workshop aimed to discuss
solutions for bandwidth optimisation on mobile networks for encrypted
content, as current solutions rely on unencrypted content which is
not indicative of the security needs of today's Internet users. The
workshop gathered IETF attendees, IAB members and participants from
various organisations involved in the telecommunications industry
including original equipment manufacturers, content providers, and
mobile network operators.
The group discussed the current Internet encryption trends and
deployment issues identified within the IETF, and the privacy needs
of users which should be adhered. Solutions designed around sharing
data from the network to the endpoints and vice versa were then
discussed as well as analysing whether issues experienced when using
current transport layer protocols are also playing a role here.
Content providers and CDNs gave their own views of their experiences
delivering their content with mobile network operators. Finally,
technical responses to regulation was discussed to help the regulated
industries relay the issues of impossible-to-implement or bad-for-
privacy technologies back to regulators.
A group of suggested solutions were devised which will be discussed
in various IETF groups moving forward.
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
working documents as Internet-Drafts. The list of current Internet-
Drafts is at http://datatracker.ietf.org/drafts/current/.
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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 November 26, 2018.
Copyright Notice
Copyright (c) 2018 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
(http://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 . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1. Understanding "Bandwidth Optimization" . . . . . . . . . 3
1.2. Topics . . . . . . . . . . . . . . . . . . . . . . . . . 4
1.3. Organization of this report . . . . . . . . . . . . . . . 5
1.4. Use of Note Well and Chatham House Rule . . . . . . . . . 5
1.5. IETF and GSMA . . . . . . . . . . . . . . . . . . . . . . 5
2. Scene Setting Sessions . . . . . . . . . . . . . . . . . . . 6
2.1. Scene Setting . . . . . . . . . . . . . . . . . . . . . . 6
2.1.1. Scope . . . . . . . . . . . . . . . . . . . . . . . . 6
2.1.2. Encryption Statistics and Radio Access Network
Differences . . . . . . . . . . . . . . . . . . . . . 7
2.2. Encryption Deployment Considerations . . . . . . . . . . 8
2.3. Awareness of User Choice (Privacy) . . . . . . . . . . . 8
3. Network or Transport Solution Sessions . . . . . . . . . . . 9
3.1. Sending Data Up / Down for Network Management Benefits . 10
3.1.1. Competition, Cooperation, and Mobile Network
Complexities . . . . . . . . . . . . . . . . . . . . 11
4. Transport Layer: Issues, Optimisation and Solutions . . . . . 11
5. Application Layer Optimisation, Caching and CDNs . . . . . . 12
6. Technical Analysis and Response to Potential Regulatory
Reaction . . . . . . . . . . . . . . . . . . . . . . . . . . 13
7. Suggested Principles and Solutions . . . . . . . . . . . . . 14
7.1. Better Collaboration . . . . . . . . . . . . . . . . . . 17
8. Since MaRNEW . . . . . . . . . . . . . . . . . . . . . . . . 17
9. Security Considerations . . . . . . . . . . . . . . . . . . . 18
10. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 19
11. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 19
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12. Informative References . . . . . . . . . . . . . . . . . . . 19
Appendix A. Workshop Attendees . . . . . . . . . . . . . . . . . 22
Appendix B. Workshop Position Papers . . . . . . . . . . . . . . 24
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 26
1. Introduction
The Internet Architecture Board (IAB) and GSM Association (GSMA) held
a joint workshop on "Managing Radio Networks in an Encrypted World"
(MaRNEW), on September 24-25, 2015. This workshop aimed to discuss
solutions for bandwidth optimisation on mobile networks for encrypted
content, as current solutions rely on unencrypted content which is
not indicative of the security needs of today's Internet users.
Mobile networks have a set of properties which places a large
emphasis on sophisticated bandwidth optimization. Encryption is
increasing on the Internet which is positive for consumer and
business privacy and security. Many existing mobile bandwidth
optimization solutions primarily operate on non-encrypted
communications; this can lead to performance issues being amplified
on mobile networks. The use of encryption on networks will continue
to increase, and with this understanding the workshop aimed to
understand how we can solve the issues of bandwidth optimization and
performance on radio networks in this encrypted world.
1.1. Understanding "Bandwidth Optimization"
For the purposes of this workshop, bandwidth optimization encompasses
a variety of technical topics related to traffic engineering,
prioritisation, optimisation and efficiency enhancements. It also
encompasses user-related topics such as specific subscription or
billing models, and may touch upon regulatory aspects or other issues
relating to government-initiated regulatory concerns.
The first category of bandwidth optimization includes:
o Caching
o Prioritisation of interactive traffic over background traffic
o Per-user bandwidth limit
The second category of bandwidth optimization may depend on one or
more of the first category optimization strategies, but may, in
particular, also encompass business-related topics such as content
delivery arrangements with content providers.
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Finally, while not strictly speaking traffic management, some
networks employ policy-based filtering (e.g., requested parental
controls) and many networks support some form of legal interception
functionality per applicable laws.
Many of these functions can continue as they are performed today,
even with encreased use of encryption. Others are using methods
which inspect parts of the communication that will be encrypted, and
these functions will have to be done differently in an increasingly
encrypted Internet.
1.2. Topics
The workshop aimed to answer questions including:
o Understanding the bandwidth optimization use cases particular to
radio networks
o Understanding existing approaches and how these do not work with
encrypted traffic
o Understanding reasons why the Internet has not standardised
support for lawful intercept and why mobile networks have
o Determining how to match traffic types with bandwidth optimization
methods
o Discussing minimal information to be shared to manage networks but
ensure user security and privacy
o Developing new bandwidth optimization techniques and protocols
within these new constraints
o Discussing the appropriate network layer(s) for each management
function
o Cooperative methods of bandwidth optimization and issues
associated with these
The further aim was to gather architectural and engineering guidance
on future work in the bandwidth optimisation area based on the
discussions around the proposed approaches. The workshop also
explored possible areas for standardization, e.g. new protocols that
can aid bandwidth optimization whilst ensuring user security inline
with new work in transport layer protocols.
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1.3. Organization of this report
This workshop report summarizes the contributions to and discussions
at the workshop, organized by topic. The workshop began with scene
setting topics which covered the issues around deploying encryption,
the increased need for privacy on the Internet and setting a clear
understanding that ciphertext should remain unbroken. Later sessions
focused on key solution areas; these included evolution on the
transport layer and sending data up or down the path. A session on
application layers and CDNs aimed to highlight both issues and
solutions experienced on the application layer. The workshop ended
with a session dedicated to technical response to regulation with
regards to encryption. The contributing documents were split between
identifying the issues experienced with encryption on radio networks
and suggested solutions. Of the solutions suggested some focused on
transport evolution, some on trusted middleboxes and others on
collaborative data exchange. Solutions were discussed within the
sessions. All accepted position papers and detailed transcripts of
discussion are available at [MARNEW].
The outcomes of the workshop are discussed in Section 7 and 8, and
discuss progress after the workshop toward each of the identified
work items as of the time of publication of this report.
Report readers should be reminded that this workshop did not aim to
discuss regulation or legislation, although policy topics were
mentioned in discussions from time to time.
1.4. Use of Note Well and Chatham House Rule
The workshop was conducted under the IETF [NOTE_WELL] with the
exception of the "Technical Analysis and Response to Potential
Regulatory Reaction" session which was conducted under
[CHATHAM_HOUSE_RULE].
1.5. IETF and GSMA
The IETF and GSMA [GSMA] have different working practices, standards
and processes. IETF is an open organisation with community driven
standards, with the key aim of functionality and security for the
Internet's users, while the GSMA is membership based and serves the
needs of its membership base, most of whom are mobile network
operators.
Unlike IETF, GSMA makes few standards. Within the telecommunications
industry standards are set in various divergent groups depending on
their purpose. Perhaps of most relevance to the bandwidth
optimisation topic here is the work of the 3rd Generation Partnership
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Project (3GPP) [SDO_3GPP] which works on radio network and core
network standards. 3GPP members include mobile operators and original
equipment manufacturers.
One of the 3GPP standards relevant to this workshop is PCC-QoS
[PCC-QOS]. Traditionally mobile networks have managed different
applications and services based on the resources available and
priorities given; for instance, emergency services have a top
priority, data has a lower priority and voice services are somewhere
in-between. 3GPP defined the PCC-QoS mechanism to support this
functionality, and this depends on unencrypted communications
[EffectEncrypt].
2. Scene Setting Sessions
Scene setting sessions aimed to bring all attendees up to a basic
understanding of the problem and the scope of the workshop. There
were three scene setting sessions: Scene Setting (defining scope),
Encryption Deployment Considerations and Trust Models and User Choice
(Privacy).
2.1. Scene Setting
The telecommunications industry and Internet standards community are
extremely different in terms of ethos and practices. Both groups
drive technical standards in their domain and build technical
solutions with some policy-driven use cases. These technologies, use
cases and technical implementations are different, and the motivators
between the two industries are also diverse.
To ensure all attendees were aligned with contributing to discussions
and driving solutions this "Scene Setting" session worked on
generating a clear scope with all attendees involved. In short: it
was agreed that ciphertext encrypted by one party and intended to be
decrypted by a second party should not be decrypted by a third party
in any solution, that the radio access network (RAN) does experience
issues with increased encrypted traffic, that we need to understand
what those problems are precisely and that our goal is to improve
user experience on the Internet. Proposing new technical solutions
based on presumed future regulation was not in scope. The full scope
is given below.
2.1.1. Scope
The attendees identified and agreed the following scope:
o In discussion we should assume: No broken crypto, Ciphertext
increasingly common, congestion does need to be controlled as do
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other transport issues and Network management including efficient
use of resources, in RAN and elsewhere, has to work
o How/why is RAN different for transport; help us understand the
complexities of the RAN and how hard it is to manage and why those
matter
o What are the precise problems caused by more ciphertext
o Identify players, in addition to end users, the resulting tensions
and how ciphertext changes those
o Some solutions will be radically changed by ciphertext, it's ok to
talk about that
o The best possible quality of experience for the end user is a goal
o Our aim for the next two days is to analyse the situation and
identify specific achievable tasks that could be tackled in the
IETF or GSMA (or elsewhere?) and that improve the Internet given
the assumptions above
o We should not delve into:
* Ways of doing interception (legal or not), for the reasons
described in [RFC2804]
* Unpredictable political actions.
2.1.2. Encryption Statistics and Radio Access Network Differences
Attendees were shown that encrypted content is reaching around 50%
according to then-current statistics [STATE_BROWSER] and
[STATE_SERVER]. The IAB is encouraging all IETF working groups to
consider the effect encryption being "on by default" will have on new
protocol work, and the IETF is also working on encryption at lower
layers. One recent example of this work is opportunistic TCP
encryption within the [TCPINC] Working Group. The aims of these work
items are greater security and privacy for end users and their data.
Telecommunications networks often contain middleboxes that operators
have previously considered to be trusted, but qualifying trust is
difficult and should not be assumed. Some interesting use cases
exist with these middleboxes, such as anti-spam and malware
detection, but these need to be balanced against their ability to
open up cracks in the network for attacks such as pervasive
monitoring.
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When operators increase the number of radio access network cells
("Base Stations"), this can improve the radio access network quality
of service , but also adds to radio pollution. This is one example
of the balancing act required when devising radio access network
architecture.
2.2. Encryption Deployment Considerations
Encryption across the Internet is on the rise. However, some
organisations and individuals come across a common set of operational
issues when deploying encryption, mainly driven by commercial
perspectives. The [UBIQUITOUS] draft explains these network
management function impacts, detailing areas around incident
monitoring, access control management, and regulation on mobile
networks. The data was collected from various Internet players,
including system and network administrators across enterprise,
governmental organisations and personal use. The aim of the document
is to gain an understanding of what is needed for technical solutions
to these issues, maintaining security and privacy for users.
Attendees commented that worthwhile additions would be: different
business environments (e.g. cloud environments) and service chaining.
Incident monitoring in particular was noted as a difficult issue to
solve given the use of URL in today's incident monitoring middleware.
Some of these impacts to mobile networks can be resolved using
difference methods and the [NETWORK_MANAGEMENT] draft details these
methods. The draft focuses heavily on methods to manage network
traffic without breaching user privacy and security.
By reviewing encryption depoyment issues and the alternative methods
of network management MaRNEW attendees were made aware of the issues
which affect radio networks, the deployment issues which are solvable
and require no further action, and those which aren't currently
solveable and which should be addressed within the workshop.
2.3. Awareness of User Choice (Privacy)
Some solutions intended to improve delivery of encrypted content
could affect some or all of the privacy benefits that encryption
provides. Understanding user needs and desires for privacy is
therefore important when designing these solutions.
From a then-current study [Pew2014] 64% of users said concerns over
privacy have increased, 67% of mobile Internet users would like to do
more to protect their privacy. The World Wide Web Consortium (W3C)
and IETF have both responded to user desires for better privacy by
recommending encryption for new protocols and web technologies.
Within the W3C new security standards are emerging and the design
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principles for HTML hold that users are the stakeholders with most
priority, followed by implementors and other stakeholders, further
enforcing the "user first" principle. Users also have certain
security expectations from particular contexts, and sometimes use new
technologies to further protect their privacy even if those
technologies weren't initially developed for that purpose.
Operators may deploy technologies which can impact user privacy
without being aware of those privacy implications or incorrectly
assume that the benefits users gain from the new technology outweigh
the loss of privacy. If these technologies are necessary they should
be opt-in.
Internet stakeholders should understand the priority of other
stakeholders. Users should be considered the first priority. Other
stakeholders include implementors, developers, advertisers, operators
and other ISPs. Some technologies such as cookie use and JavaScript
injection have been abused by these parties. This has caused some
developers to encrypt content to circumvent these technologies which
are seen as intrusive or bad for user privacy.
If users and content providers are to opt-in to network management
services with negative privacy impacts, they should see clear value
from using these services, and understand the impacts of using these
services. Users should also have easy abilities to opt-out. Some
users will always automatically click through consent requests, so
any model relying on explicit consent is flawed for these users.
Understanding the extent of "auto click through" may improve
decisions about the use of consent requests in the future. One model
(Cooperative Traffic Management) works as an agent of the user; by
opting-in metadata can be shared. Issues with this involve trust
only being applied at endpoints.
3. Network or Transport Solution Sessions
Network or Transport Solution Sessions aimed to discuss proposed
solutions for managing encrypted traffic on radio access networks.
Most solutions focus on metadata sharing, whether this sharing takes
place from the endpoint to the network, from the network to the
endpoint, or cooperatively in both directions. Transport layer
protocol evolution could be another approach to solve some of the
issues radio access networks erience which cause them to rely on
network management middleboxes. By removing problems at the
transport layer, reliance on expensive and complex middleboxes could
decrease.
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3.1. Sending Data Up / Down for Network Management Benefits
Collaboration between network elements and endpoints could bring
about better content distribution. A number of suggestions were
given; these included:
o Mobile Throughput Guidance [MTG]: exchanges metadata between
network elements and endpoints via TCP Options. It also allows
for better understanding of how the transport protocol behaves and
improving user experience further, although additional work on MTG
is still required.
o SPUD [SPUD]: a UDP-based encapsulation protocol to allow explicit
cooperation with middleboxes while using new, encrypted transport
protocols.
o Network Status API: An API for operators to share congestion
status or the state of a cell before an application starts sending
data could allow applications to change their behaviour.
o Traffic classification: classifying traffic and adding these
classifications as metadata for analysis throughout the network.
This idea has trust and privacy implications.
o ConEx [CONEX]: a mechanism where senders inform the network about
the congestion encountered by previous packets on the same flow,
in-band at the IP layer.
o Latency versus Bandwidth: allowing the content provider to
indicate whether higher bandwidth or lower latency is of greater
priority and allowing the network to react based on that
indication. Where this bit resides in the protocol stack and how
it is authenticated would need to be decided.
o No network management tools: disabling all network management
tools from the network and rely only on end-to-end protocols to
manage congestion.
o Fairness-aware Delay-controlled Controlled Delay (FD-CoDel)
[FLOWQUEUE]: a hybrid packet scheduler/Active Queue Management
(AQM, [RFC7567]) algorithm, aiming to reduce bufferbloat and
latency. FQ-CoDel manages packets from multiple flows and reduces
the impact of head-of-line blocking from bursty traffic.
Some of these suggestions rely on signaling from network elements to
endpoint. Others aim to create "hop-to-hop" solutions, which could
be more aligned with how congestion is managed today, but with
greater privacy implications.
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Still others rely on signaling from endpoints to network elements.
Some of these rely on implicit signaling, and others on explicit
signaling. Some workshop attendees agreed that relying on
applications to explicitly declare the quality of service they
require was not a good path forward, given the lack of success with
this model in the past.
3.1.1. Competition, Cooperation, and Mobile Network Complexities
One of the larger issues in the sharing of data about the problems
encountered with encrypted traffic in wireless networks is the matter
of competition; network operators are reluctant to relinquish data
about their own networks because it contains information that is
valuable to competitors, and application providers wish to protect
their users and reveal as little information as possible to the
network. Some people think that if middleboxes were authenticated
and invoked explicitly, this would be an improvement over current
transparent middleboxes that intercept traffic without endpoint
consent. Some workshop attendees suggested any exchange of
information should be bidirectional, in an effort to improve
cooperation between the elements. A robust incentive framework could
provide a solution to these issues, or at least help mitigate them.
The radio access network is complex because it must deal with a
number of conflicting demands. Base stations reflect this
environment, and information within these base stations can be of
value to other entities on the path. Some workshop participants
thought solutions for managing congestion on radio networks should
involve the base station if possible. For instance, understanding
how the Radio Resource Controller and AQM [RFC7567] interact (or
don't interact) could provide valuable information for solving
issues. Although many workshop attendees agreed that even though
there is a need to understand the base station, not all agreed that
the base station should be part of a future solution.
Some suggested solutions were based on network categorisation and on
providing this information to the protocols or endpoints. Completely
categorising radio networks could be impossible due to their
complexity, but categorising essential network properties could be
possible and valuable.
4. Transport Layer: Issues, Optimisation and Solutions
TCP has been the dominant transport protocol since TCP/IP replaced
the NCP Network Control Protocol on the Arpanet in March 1983. TCP
was originally devised to work on a specific network model that did
not anticipate the high error rates and highly variable available
bandwidth scenarios experienced on modern radio access networks.
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Furthermore new network elements have been introduced (NATs and
network devices with large buffers creating bufferbloat), and
considerable peer-to-peer traffic is competing with traditional
client-server traffic. Consequently the transport layer today has
requirements beyond what TCP was designed to meet. TCP has other
issues as well; too many services rely on TCP and only TCP, blocking
deployment of new transport protocols like SCTP and DCCP. This means
that true innovation on the transport layer becomes difficult because
deployment issues are more complicated than just building a new
protocol.
The IETF is trying to solve these issues through the IAB's "Stack
Evolution" programme, and the first step in this programme is to
collect data. Network and content providers can provide data
including: the cost of encryption, the advantages of network
management tools, the deployment of protocols, and the effects when
network management tools are disabled. Network operators do not tend
to reveal network information mostly for competitive reasons and so
are unlikely to donate this information freely to IETF. The GSMA is
in a position to try to collect this data and anonymise it before
bringing it to IETF which should alleviate the network operator
worries but still provide IETF with some usable data.
A considerable amount of work has already been done on TCP,
especially innovation in bandwidth management and congestion control;
although congestion is only detected when packet loss is encountered,
and better methods based on detecting congestion would be beneficial.
Furthermore, although the deficiencies of TCP are often considered as
key issues in the evolution of the Internet protocol stack, the main
route to resolve these issues may not be a new TCP, but an evolved
stack. Some workshop participants thought SPUD [SPUD] and ICN
[RFC7476] are two suggestions which may help here. QUIC [QUIC]
engineers stated that the problems solved by QUIC are general
problems, rather than TCP issues. This view was not shared by all
attendees of the workshop. Moreover, TCP has had some improvements
in the last few years which may mean some of the network lower layers
should be investigated to see whether improvements can be made here.
5. Application Layer Optimisation, Caching and CDNs
Many discussions on the effects of encrypted traffic on radio access
networks happen between implementers and the network operators; this
session aimed to gather the opinions of the content and caching
providers including their experiences running over mobile networks,
the quality of experience their users expect, and what content and
caching providers would like to achieve by working with or using the
mobile network.
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Content providers explained how even though this workshop cited
encrypted data over radio access networks as the main issue, the real
issue is network management generally, and all actors (applications
providers, networks and devices) need to work together to overcome
these general network management issues. Content providers explained
how they assume the mobile networks are standard compliant. When the
network is not standards compliant (e.g. using non-standards-
compliant intermediaries) content providers can experience real costs
as users contact their support centres to report issues which are
difficult to test for and resolve.
Content providers cited other common issues concerning data traffic
over mobile networks. Data subscription limits ("caps") cause issues
for users; users are confused about how data caps work or are unsure
how expensive media is and how much data it consumes. Developers
build products on networks not indicative of the networks their
customers are using and not every organisation has the finances to
build a caching infrastructure.
Strongly related to content providers, content owners consider CDNs
to be trusted deliverers of content and CDNs have shown great success
in fixed networks. Now that more traffic is moving to mobile
networks there is a need to place caches at the edge of the mobile
network, near the users. Placing caches at the edge of the mobile
network is a solution, but requires standards developed by content
providers and mobile network operators. The CNDi Working Group
[CDNI] at IETF aims to allow global CDNs to interoperate with mobile
CDNs; but this causes huge issues for the caching of encrypted data
between these CDNs. Some CDNs are experimenting with approaches like
"Keyless SSL" [KeylessSSL] to enable safer storage of content without
passing private keys to the CDN. Blind Caching [BLIND_CACHING] is
another proposal aimed at caching encrypted content closer to the
user and managing the authentication at the original content provider
servers.
At the end of the session each panelist was asked to identify one key
collaborative work item. Work items named were: evolving to cache
encrypted content, using one-bit for latency / bandwidth trade-off
(explained below), better collaboration between the network and
application, better metrics to aid troubleshooting and innovation,
and indications from the network to allow the application to adapt.
6. Technical Analysis and Response to Potential Regulatory Reaction
This session was conducted under Chatham House Rule. The session
aimed to discuss regulatory and political issues, but not their worth
or need; rather to understand the laws that exist and how
technologists can properly respond to these.
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Mobile networks are regulated, compliance is mandatory (and non-
compliance can result in service license revocation in some nations)
and can incur costs on the mobile network operator. Regulation does
vary geographically. Some regulations are court orders, others are
self-imposed regulations, for example, "block lists" of websites such
as the Internet Watch Foundation list [IWF]. Operators are not
expected to decrypt sites, so those encrypted sites will not be
blocked because of content.
Parental control-type filters also exist on the network and are
easily bypassed today, vastly limiting their effectiveness. Better
solutions would allow for users to easily set these restrictions
themselves. Other regulations are also hard to meet, such as user
data patterns, or will become harder to collect - such as "Internet
of Things" (IoT) cases. Most attendees agreed that if a government
cannot get information it needs and is legally entitled to have from
network operators they will approach content providers. Some
governments are aware of the impact of encryption and are working
with, or trying to work with, content providers. The IAB has
concluded blocking and filtering can be done at the endpoints of the
communication.
Not all of these regulations apply to the Internet, and the Internet
community is not always aware of their existence. Collectively the
Internet community can work with GSMA and 3GPP and act collectively
to alleviate the risk imposed by encrypted traffic. Some
participants expressed concern that governments might require
operators to provide information that they no longer have the ability
to provide, because previously-unencrypted traffic is now being
encrypted, and this might expose operators to new liability, but no
specific examples were given during the workshop. A suggestion from
some attendees was that if any new technical solutions are necessary,
they should easily be "switched off".
Some mobile network operators are producing transparency reports
covering regulations including lawful intercept. Operators who have
done this already are encouraging others to do the same.
7. Suggested Principles and Solutions
Based on the talks and discussions throughout the workshop a set of
suggested principles and solutions has been collected. This is not
an exhaustive list, and no attempt was made to come to consensus
during the workshop, so there are likely at least some participants
who would not agree with any particular principle listed below. The
list is a union of participant thinking, not an intersection.
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o Encrypted Traffic: any solution should encourage and support
encrypted traffic.
o Flexibility: radio access network qualities vary vastly and the
network needs of content can differ significantly, so any new
solution should be flexible across either the network type,
content type, or both.
o Privacy: new solutions should not introduce new ways where
information can be discovered and attributed to individual users.
o Minimum data only for collaborative work: user data, application
data, and network data all needs protection, so new solutions
should use the minimum information to make a working solution.
A collection of solutions suggested by various participants during
the workshop is given below. Inclusion in this list does not imply
that other workshop participants agreed. Again, the list is a union
of proposed solutions, not an intersection.
o Evolving TCP or evolution on the transport layer: this could take
a number of forms and some of this work is already underway within
the IETF.
o Congestion Control: many attendees cited congestion control as a
key issue. Further analysis, investigation and work could be done
in this space.
o SPROUT: research at MIT which is a transport protocol for
applications that desire high throughput and low delay. [SPROUT]
o PCC: Performance-oriented Congestion Control: is a new
architecture that aims for consistent high performance even in
challenging scenarios. PCC endpoints observe the connection
between their actions and their known performance, which allows
them to adapt their actions. [PCC]
o CDNs and Caches: placing caches closer to the edge of the radio
network, as close as possible to the mobile user, or making more
intelligent CDNs would result in faster content delivery and less
strain on the network.
o Blind Caching: a proposal for caching of encrypted content
[BLIND_CACHING].
o CDN improvements: including keyless SSL and better CDN placement.
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o Mobile Throughput Guidance: a mechanism and protocol elements that
allow the cellular network to provide near real-time information
on capacity available to the TCP server. [MTG]
o One bit for latency / bandwidth trade-off: determining whether
using a single bit in an unencrypted transport header to
distinguish between traffic that the sender prefers to be queued
and traffic that the sender would prefer to drop rather than delay
provides additional benefits beyond what can be achieved without
this signaling.
o Base Station: some suggestions involved "using the Base Station",
but this was not defined in detail. The Base Station holds the
Radio Resource Controller and scheduler which could provide a
place to host solutions, or data from the Base Station could help
in devising new solutions.
o Identify traffic types via 5-tuple: information from the 5-tuple
could provide understanding of the traffic type, and network
management appropriate for that traffic type could then be
applied.
o Heuristics: Networks can sometimes identify traffic types by
observing characteristics such as data flow rate and then apply
network management to these identified flows. This is not
recommended as categorisations can be incorrect.
o APIs: An API for operators to share congestion status or the state
of a cell before an application starts sending data could allow
applications to change their behaviour. Alternatively an API
could provide the network with information on the data type,
allowing appropriate network management for that data type,
although this method exposes privacy issues.
o Standard approach for operator to offer services to Content
Providers: mobile network operators could provide caching services
or other services for content providers to use for faster and
smoother content delivery.
o AQM [RFC7567] and ECN [RFC3168] deployments: queuing and
congestion management methods have existed for some time in the
form of AQM, ECN and others which can help the transport and
Internet protocol layers adapt to congestion faster.
o Trust Model or Trust Framework: some solutions in this area (e.g.
SPUD) have a reliance on trust when content providers or the
network are being asked to add classifiers to their traffic.
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o Keyless SSL [KeylessSSL]: allows content providers to maintain
their private keys on a "key server" and host the content
elsewhere (e.g. on a CDN). This could become standardised in
IETF. [LURK]
o Meaningful capacity sharing: including the ConEx [CONEX] work
which exposes information about congestion to the network nodes.
o Hop-by-hop: some suggestions offer hop-by-hop methods allowing
nodes to adapt flow given the qualities of the networks around
them and the congestion they are experiencing.
o Metrics and metric standards: in order to evolve current protocols
to be best suited to today's networks, data is needed about
current network conditions, protocol deployments, packet traces
and middlebox behaviour. Beyond this, proper testing and
debugging on networks could provide great insight for stack
evolution.
o 5G: Mobile operator standards bodies are in the process of setting
the requirements for 5G. Requirements for network management
could be added.
In the workshop, attendees identified other areas where greater
understanding could help the standards process. These were
identified as:
o Greater understanding of the RAN at IETF.
o Reviews and comments on 3GPP perspective.
o How to do congestion control in the RAN.
7.1. Better Collaboration
Throughout the workshop attendees placed emphasis on the need for
better collaboration between the IETF and telecommunications bodies
and organisations. The workshop was one such way to achieve this,
but the good work and relationships built in the workshop should
continue so the two groups can work on solutions which are better for
both technologies and users.
8. Since MaRNEW
Since MaRNEW a number of activities have taken place in various IETF
working groups, and in groups external to IETF. The ACCORD BoF was
held at IETF 95 in November 2015, which brought the workshop
discussion to the wider IETF audiences by providing an account of the
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discussions that had taken place within the workshop and highlighting
key areas to progress on. Key areas to progress and an update on
their current status follows:
o The collection of useable metrics and data were requested by a
number of MaRNEW attendees, especially for use within the IRTF
Measurement and Analysis for Protocols (MAP) Research Group; this
data has been difficult to collect due to the closed nature of
mobile network operators.
o Understanding impediments to protocol stack evolution has
continued within the IAB's Stack Evolution programme and
throughout transport-related IETF working groups such as the
Transport Area Working Group (TSVWG).
o The Mobile Throughput Guidance draft has entered into a testing
and data collection phase; although further advancements in
transport technologies (among others, QUIC) may have stalled
efforts in TCP-related proposals.
o Work on proposals for caching encrypted content continue, albeit
with some security flaws which proponents are working on further
proposals to fix. Most often these are discussed within the IETF
HTTPbis working group.
o The PLUS BOF at IETF 96 in July 2016 did not result in the
formation of a working group, with attendees expressing concern on
the privacy issues associated with the data sharing possibilities
of the shim layer proposed.
o The LURK BOF at IETF 96 in July 2016 did not result in the
formation of a working group, because the BOF identified more
problems with the presumed approach than anticipated.
The most rewarding output of MaRNEW is perhaps the most intangible.
MaRNEW gave two rather divergent industry groups the opportunity to
connect and discuss common technologies and issues affecting users
and operations. Mobile Network providers and key Internet engineers
and experts have developed a greater collaborative relationship to
aid development of further standards which work across networks in a
secure manner.
9. Security Considerations
This document is an IAB report from a workshop on interactions
between network security, especially privacy, and network
performance.
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It does not affect the security of the Internet, taken on its own.
10. IANA Considerations
This document makes no requests of IANA.
11. Acknowledgements
Stephen Farrell reviewed this report in draft form and provided
copious comments and suggestions.
Barry Leiba provided some clarifications on specific discussions
about Lawful Intercept that took place during the workshop.
Bob Hinden and Warren Kumari provided comments and suggestions during
the IAB Call for Comments.
Amelia Andersdotter and Shivan Kaul Sahib provided comments from the
Human Rights Review Team during the IAB Call for Comments.
12. Informative References
[BLIND_CACHING]
Holmberg, M., "Caching Secure HTTP Content using Blind
Caches", October 2016, <https://www.ietf.org/archive/id/
draft-thomson-http-bc-01.txt>.
[CDNI] "Content Delivery Networks Interconnection Working Group",
n.d., <https://datatracker.ietf.org/wg/cdni/charter/>.
[CHATHAM_HOUSE_RULE]
"Chatham House Rule", n.d.,
<https://www.chathamhouse.org/about/chatham-house-rule>.
[CONEX] "Congestion Exposure Working Group", n.d.,
<https://datatracker.ietf.org/wg/conex/documents/>.
[EffectEncrypt]
Patel, C., "The effect of encrypted traffic on the QoS
mechanisms in cellular networks", August 2015,
<https://www.iab.org/wp-content/IAB-uploads/2015/08/
MaRNEW_1_paper_25.pdf>.
[FLOWQUEUE]
Dumazet, P., "FlowQueue-Codel", March 2014,
<https://tools.ietf.org/html/draft-hoeiland-joergensen-
aqm-fq-codel-00>.
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[GSMA] "GSMA Homepage", n.d., <http://gsma.com>.
[IWF] "Internet Watch Foundation", n.d.,
<https://www.iwf.org.uk/>.
[KeylessSSL]
Sullivan, N., "Keyless SSL: The Nitty Gritty Technical
Details", September 2014, <https://blog.cloudflare.com/
keyless-ssl-the-nitty-gritty-technical-details/>.
[LURK] Ma, D., "TLS/DTLS Content Provider Edge Server Split Use
Case", January 2016, <https://tools.ietf.org/html/draft-
mglt-lurk-tls-use-cases-00>.
[MARNEW] "MaRNEW Workshop IAB Homepage", n.d.,
<https://www.iab.org/activities/workshops/marnew/>.
[MTG] Smith, A., "Mobile Throughput Guidance Inband Signaling
Protocol", September 2015,
<https://www.ietf.org/archive/id/draft-flinck-mobile-
throughput-guidance-03.txt>.
[NETWORK_MANAGEMENT]
Smith, K., "Network management of encrypted traffic", May
2015, <https://tools.ietf.org/html/draft-smith-encrypted-
traffic-management-00>.
[NOTE_WELL]
"IETF Note Well", n.d., <https://www.ietf.org/about/note-
well.html>.
[PCC] Schapira, M., "PCC, Re-architecting Congestion Control for
Consistent High Performance", May 2015,
<http://arxiv.org/pdf/1409.7092v3.pdf>.
[PCC-QOS] "Policy and charging control signalling flows and Quality
of Service (QoS) parameter mapping", March 2016,
<http://www.3gpp.org/DynaReport/29213.htm>.
[Pew2014] "Public Perceptions of Privacy and Security in the Post-
Snowden Era", November 2014,
<http://www.pewinternet.org/2014/11/12/
public-privacy-perceptions/>.
[QUIC] Swett, J., "QUIC, A UDP-Based Secure and Reliable
Transport for HTTP/2", June 2015,
<https://tools.ietf.org/html/draft-tsvwg-quic-protocol-
00>.
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[RFC2804] IAB and IESG, "IETF Policy on Wiretapping", RFC 2804,
DOI 10.17487/RFC2804, May 2000, <https://www.rfc-
editor.org/info/rfc2804>.
[RFC3168] Ramakrishnan, K., Floyd, S., and D. Black, "The Addition
of Explicit Congestion Notification (ECN) to IP",
RFC 3168, DOI 10.17487/RFC3168, September 2001,
<https://www.rfc-editor.org/info/rfc3168>.
[RFC7476] Pentikousis, K., Ed., Ohlman, B., Corujo, D., Boggia, G.,
Tyson, G., Davies, E., Molinaro, A., and S. Eum,
"Information-Centric Networking: Baseline Scenarios",
RFC 7476, DOI 10.17487/RFC7476, March 2015,
<https://www.rfc-editor.org/info/rfc7476>.
[RFC7567] Baker, F., Ed. and G. Fairhurst, Ed., "IETF
Recommendations Regarding Active Queue Management",
BCP 197, RFC 7567, DOI 10.17487/RFC7567, July 2015,
<https://www.rfc-editor.org/info/rfc7567>.
[SDO_3GPP]
"3GPP Homepage", n.d., <http://www.3gpp.org/>.
[SPROUT] Balakrishnan, K., "Stochastic Forecasts Achieve High
Throughput and Low Delay over Cellular Networks", April
2013,
<https://www.usenix.org/system/files/conference/nsdi13/
nsdi13-final113.pdf>.
[SPUD] "Session Protocol for User Datagrams", n.d.,
<https://datatracker.ietf.org/wg/spud/documents/>.
[STATE_BROWSER]
Barnes, R., "Some observations of TLS in the web", July
2015, <https://www.ietf.org/proceedings/93/slides/slides-
93-saag-3.pdf>.
[STATE_SERVER]
Salz, R., "Some observations of TLS in the web", July
2015, <https://www.ietf.org/proceedings/93/slides/slides-
93-saag-4.pdf>.
[TCPINC] "TCP Increased Security Working Group", n.d.,
<https://datatracker.ietf.org/wg/tcpinc/charter/>.
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[UBIQUITOUS]
Morton, K., "Effect of Ubiquitous Encryption", March 2015,
<https://tools.ietf.org/html/draft-mm-wg-effect-encrypt-
01>.
Appendix A. Workshop Attendees
o Rich Salz, Akamai
o Aaron Falk, Akamai
o Vinay Kanitkar, Akamai
o Julien Maisonneuve, Alcatel Lucent
o Dan Druta, AT&T
o Humberto La Roche, Cisco
o Thomas Anderson, Cisco
o Paul Polakos, Cisco
o Marcus Ihlar, Ericsson
o Szilveszter Nadas, Ericsson
o John Mattsson, Ericsson
o Salvatore Loreto, Ericsson
o Blake Matheny, Facebook
o Andreas Terzis, Google
o Jana Iyengar, Google
o Natasha Rooney, GSMA
o Istvan Lajtos, GSMA
o Emma Wood, GSMA
o Jianjie You, Huawei
o Chunshan Xiong, Huawei
o Russ Housley, IAB
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o Mary Barnes, IAB
o Joe Hildebrand, IAB / Cisco
o Ted Hardie, IAB / Google
o Robert Sparks, IAB / Oracle
o Spencer Dawkins, IETF AD
o Benoit Claise, IETF AD / Cisco
o Kathleen Moriarty, IETF AD / EMC
o Barry Leiba, IETF AD / Huawei
o Ben Campbell, IETF AD / Oracle
o Stephen Farrell, IETF AD / Trinity College Dublin
o Jari Arkko, IETF Chair / Ericsson
o Karen O'Donoghue, ISOC
o Phil Roberts, ISOC
o Olaf Kolkman, ISOC
o Christian Huitema, Microsoft
o Patrick McManus, Mozilla
o Dirk Kutscher, NEC Europe Network Laboratories
o Mark Watson, Netflix
o Martin Peylo, Nokia
o Mohammed Dadas, Orange
o Diego Lopez, Telefonica
o Matteo Varvello, Telefonica
o Zubair Shafiq, The University of Iowa
o Vijay Devarapalli, Vasona Networks
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o Sanjay Mishra, Verizon
o Gianpaolo Scassellati, Vimplecom
o Kevin Smith, Vodafone
o Wendy Seltzer, W3C
Appendix B. Workshop Position Papers
o Mohammed Dadas, Emile Stephan, Mathilde Cayla, Iuniana Oprescu,
"Cooperation Framework between Application layer and Lower Layers"
at https://www.iab.org/wp-content/IAB-uploads/2015/08/
MaRNEW_1_paper_33.pdf
o Julien Maisonneuve, Thomas Fossati and Vijay Gurbani, "The
security pendulum and the network" at https://www.iab.org/wp-
content/IAB-uploads/2015/08/MaRNEW_1_paper_4.pdf
o Martin Peylo, "Enabling Secure QoE Measures for Internet
Applications over Radio Networks is a MUST" at
https://www.iab.org/wp-content/IAB-uploads/2015/08/
MaRNEW_1_paper_32.pdf
o Vijay Devarapalli, "The bandwidth balancing act: Managing QoE as
encrypted services change the traffic optimization game" at
https://www.iab.org/wp-content/IAB-uploads/2015/08/
MaRNEW_1_paper_10.pdf
o Humberto La Roche, "Use Cases for Communicating End-Points in
Mobile Network Middle-Boxes" at https://www.iab.org/wp-content/
IAB-uploads/2015/08/MaRNEW_1_paper_12.pdf
o Richard Barnes and Patrick McManus, "User Consent and Security as
a Public Good" at https://www.iab.org/wp-content/IAB-
uploads/2015/08/MaRNEW_1_paper_13.pdf
o Iuniana Oprescu, Jon Peterson and Natasha Rooney, "A Framework for
Consent and Permissions in Mediating TLS" at https://www.iab.org/
wp-content/IAB-uploads/2015/08/MaRNEW_1_paper_31.pdf
o Jari Arkko and Goeran Eriksson, "Characteristics of Traffic Type
Changes and Their Architectural Implications" at
https://www.iab.org/wp-content/IAB-uploads/2015/08/
MaRNEW_1_paper_15.pdf
o Szilveszter Nadas and Attila Mihaly, "Traffic Management for
Encrypted Traffic focusing on Cellular Networks" at
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https://www.iab.org/wp-content/IAB-uploads/2015/08/
MaRNEW_1_paper_16.pdf
o Gianpaolo Scassellati, "Vimpelcom Position Paper for MaRNEW
Meeting" at https://www.iab.org/wp-content/IAB-uploads/2015/09/
MaRNEW_1_paper_17.pdf
o Mirja Kuehlewind, Dirk Kutscher and Brian Trammell, "Enabling
Traffic Management without DPI" at https://www.iab.org/wp-content/
IAB-uploads/2015/08/MaRNEW_1_paper_18.pdf
o Andreas Terzis and Chris Bentzel, "Sharing network state with
application endpoints" at https://www.iab.org/wp-content/IAB-
uploads/2015/08/MaRNEW_1_paper_19.pdf
o Marcus Ihlar, Robert Skog and Salvatore Loreto, "The needed
existence of Performance Enhancing Proxies in an Encrypted World"
at https://www.iab.org/wp-content/IAB-uploads/2015/08/
MaRNEW_1_paper_20.pdf
o John Mattsson, "Network Operation in an All-Encrypted World" at
https://www.iab.org/wp-content/IAB-uploads/2015/08/
MaRNEW_1_paper_21.pdf
o Dirk Kutscher, Giovanna Carofiglio, Luca Muscariello and Paul
Polakos, "Maintaining Efficiency and Privacy in Mobile Networks
through Information-Centric Networking" at https://www.iab.org/wp-
content/IAB-uploads/2015/08/MaRNEW_1_paper_23.pdf
o Chunshan Xiong and Milan Patel, "The effect of encrypted traffic
on the QoS mechanisms in cellular networks" at
https://www.iab.org/wp-content/IAB-uploads/2015/08/
MaRNEW_1_paper_25.pdf
o Thomas Anderson, Peter Bosch and Alessandro Duminuco, "Bandwidth
Control and Regulation in Mobile Networks via SDN/NFV-Based
Platforms" at https://www.iab.org/wp-content/IAB-uploads/2015/08/
MaRNEW_1_paper_26.pdf
o Karen O'Donoghue and Phil Roberts, Barriers to Deployment:
"Probing the Potential Differences in Developed and Developing
Infrastructure" at https://www.iab.org/wp-content/IAB-
uploads/2015/08/MaRNEW_1_paper_27.pdf
o Wendy Seltzer, "Performance, Security, and Privacy Considerations
for the Mobile Web" at https://www.iab.org/wp-content/IAB-
uploads/2015/08/MaRNEW_1_paper_28.pdf
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o Jianjie You, Hanyu Wei and Huaru Yang, "Use Case Analysis and
Potential Bandwidth Optimization Methods for Encrypted Traffic" at
https://www.iab.org/wp-content/IAB-uploads/2015/08/
MaRNEW_1_paper_29.pdf
o Mangesh Kasbekar and Vinay Kanitkar, "CDNs, Network Services and
Encrypted Traffic" at https://www.iab.org/wp-content/IAB-
uploads/2015/08/MaRNEW_1_paper_30.pdf
o Claude Rocray, Mark Santelli and Yves Hupe, "Providing
Optimization of Encrypted HTTP Traffic" at https://www.iab.org/wp-
content/IAB-uploads/2015/08/MaRNEW_1_paper_341.pdf
o Zubair Shafiq, "Tracking Mobile Video QoE in the Encrypted
Internet" at https://www.iab.org/wp-content/IAB-uploads/2015/08/
MaRNEW_1_paper_35.pdf
o Kevin Smith, "Encryption and government regulation: what happens
now?" at https://www.iab.org/wp-content/IAB-uploads/2015/09/
MaRNEW_1_paper_1.pdf
Authors' Addresses
Natasha Rooney
GSMA
Email: nrooney@gsma.com
URI: https://gsma.com
Spencer Dawkins (editor)
Wonder Hamster
Email: spencerdawkins.ietf@gmail.com
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