| Rfc | 8462 |
|---|
| Title | Report from the IAB Workshop on Managing Radio Networks in an
Encrypted World (MaRNEW) |
|---|
| Author | N. Rooney, S. Dawkins, Ed. |
|---|
| Date | October 2018 |
|---|
| Format: | TXT, HTML |
|---|
| Status: | INFORMATIONAL |
|---|
|
Internet Architecture Board (IAB) N. Rooney
Request for Comments: 8462 S. Dawkins, Ed.
Category: Informational October 2018
ISSN: 2070-1721
Report from the IAB Workshop on
Managing Radio Networks in an Encrypted World (MaRNEW)
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 optimization 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 organizations involved in the telecommunications industry
including original equipment manufacturers, content providers, and
mobile network operators.
The group discussed Internet encryption trends and deployment issues
identified within the IETF and the privacy needs of users that should
be adhered to. Solutions designed around sharing data from the
network to the endpoints and vice versa were then discussed; in
addition, issues experienced when using current transport-layer
protocols were also discussed. Content providers and Content
Delivery Networks (CDNs) gave their own views of their experiences
delivering their content with mobile network operators. Finally,
technical responses to regulation were 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 document is not an Internet Standards Track specification; it is
published for informational purposes.
This document is a product of the Internet Architecture Board (IAB)
and represents information that the IAB has deemed valuable to
provide for permanent record. It represents the consensus of the
Internet Architecture Board (IAB). Documents approved for
publication by the IAB 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/rfc8462.
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
(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 . . . . . . . . . . . . . . . . . . . . . . . . 4
1.1. Understanding "Bandwidth Optimization" . . . . . . . . . 4
1.2. Topics . . . . . . . . . . . . . . . . . . . . . . . . . 5
1.3. Organization of This Report . . . . . . . . . . . . . . . 5
1.4. Use of Note Well and the Chatham House Rule . . . . . . . 6
1.5. IETF and GSMA . . . . . . . . . . . . . . . . . . . . . . 6
2. Scene-Setting Sessions . . . . . . . . . . . . . . . . . . . 7
2.1. Scene Setting . . . . . . . . . . . . . . . . . . . . . . 7
2.1.1. Scope . . . . . . . . . . . . . . . . . . . . . . . . 8
2.1.2. Encryption Statistics and Radio Access Network
Differences . . . . . . . . . . . . . . . . . . . . . 8
2.2. Encryption Deployment Considerations . . . . . . . . . . 9
2.3. Awareness of User Choice (Privacy) . . . . . . . . . . . 10
3. Network or Transport Solution Sessions . . . . . . . . . . . 11
3.1. Sending Data Up/Down for Network Management Benefits . . 11
3.1.1. Competition, Cooperation, and Mobile Network
Complexities . . . . . . . . . . . . . . . . . . . . 12
4. Transport Layer: Issues, Optimization, and Solutions . . . . 13
5. Application-Layer Optimization, Caching, and CDNs . . . . . . 14
6. Technical Analysis and Response to Potential Regulatory
Reaction . . . . . . . . . . . . . . . . . . . . . . . . . . 15
7. Suggested Principles and Solutions . . . . . . . . . . . . . 16
7.1. Better Collaboration . . . . . . . . . . . . . . . . . . 19
8. Since MaRNEW . . . . . . . . . . . . . . . . . . . . . . . . 19
9. Security Considerations . . . . . . . . . . . . . . . . . . . 20
10. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 20
11. Informative References . . . . . . . . . . . . . . . . . . . 20
Appendix A. Workshop Attendees . . . . . . . . . . . . . . . . . 24
Appendix B. Workshop Position Papers . . . . . . . . . . . . . . 26
Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . . 28
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 28
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 optimization 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 that place a large emphasis
on sophisticated bandwidth optimization. The use of encryption is
increasing on the Internet, which is positive for consumer and
business privacy and security. Many existing solutions for mobile
bandwidth optimization 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; 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,
prioritization, optimization, and efficiency enhancements. It also
encompasses user-related topics such as specific subscription or
billing models, and it may touch upon regulatory aspects or other
issues relating to government-initiated regulatory concerns.
The first category of bandwidth optimization includes the following:
o Caching
o Prioritization of interactive traffic over background traffic
o Per-user bandwidth limits
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.
Finally, while not strictly speaking of 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 increased use of encryption. Others are using methods that
inspect parts of the communication that are not encrypted today, but
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 that focused on:
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 standardized
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; and
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 optimization 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 that user security is
in line with new work in transport-layer protocols.
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 that 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 discussing a technical response to
regulation with regards to encryption. The contributing documents
identified 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 Sections 7 and 8; they
discuss the progress made since the workshop toward each of the
identified work items through the time this document was approved for
publication.
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 the 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 the
[CHATHAM_HOUSE_RULE].
1.5. IETF and GSMA
The IETF and GSMA [GSMA] have different working practices, standards,
and processes. IETF is an open organization 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
optimization topic here is the work of the 3rd Generation Partnership
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 Policy and
Charging Control 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:
o Section 2.1: Scene Setting
o Section 2.2: Encryption Deployment Considerations
o Section 2.3: Awareness of 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 1) 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, 2) the Radio Access Network (RAN) does
experience issues with increased encrypted traffic, 3) the RAN issues
need to be understood precisely, and 4) the 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 to the scope described here.
We should do the following:
o in discussion, assume that there is no broken crypto; ciphertext
is increasingly common; congestion does need to be controlled (as
do other transport issues); and network management, including
efficient use of resources in RAN and elsewhere, has to work;
o identify how/why RAN is different for transport, and attempt to
understand the complexities of RAN (i.e., how hard it is to
manage) and why those complexities matter;
o identify the precise problems caused by increased use of
encryption;
o identify players (in addition to end users), the resulting
tensions, and how ciphertext changes those tensions;
o discuss how some solutions will be radically changed by ciphertext
(it's ok to talk about that)
o assume that the best possible quality of experience for the end
user is a goal; and lastly,
o for the next two days, aim to analyze 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.
We should not delve into the following:
o ways of doing interception, legal or not, for the reasons
described in [RFC2804]; and,
o unpredictable political actions.
2.1.2. Encryption Statistics and Radio Access Network Differences
According to then-current statistics, attendees were shown that
encrypted content reaches around 50% [STATE_BROWSER] [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. The
IETF is also working on encryption at lower layers. One recent
example of this work is opportunistic TCP encryption within the TCP
Increased Security [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.
When operators increase the number of radio access network cells
(base stations), this can improve the radio access network quality of
service; however, it 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
organizations and individuals that are mainly driven by commercial
perspectives come across a common set of operational issues when
deploying encryption. [RFC8404] 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 organizations, and
personal use. The aim of the document is to gain an understanding of
what is needed for technical solutions to these issues while
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
URLs in today's incident monitoring middleware.
Some of these impacts to mobile networks can be resolved using
different methods, and the [NETWORK_MANAGEMENT] document details
these methods. The document focuses heavily on methods to manage
network traffic without breaching user privacy and security.
By reviewing encryption deployment issues and the alternative methods
of network management, MaRNEW attendees were made aware of the issues
that affect radio networks, the deployment issues that are solvable
and require no further action, and those issues that have not yet
been solved but 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, and 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
principles for HTML maintain that users are the stakeholders with the
highest priority, followed by implementors and other stakeholders,
which further enforces 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 that can either 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 that 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 discussed 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 experience, which cause them to rely on network
management middleboxes. By removing problems at the transport layer,
reliance on expensive and complex middleboxes could decrease.
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 the following:
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
further improves the user experience, although additional work on
MTG is still required.
o Session Protocol for User Datagrams [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 that could allow applications to change their behavior.
o Traffic Classification: classifying traffic and adding these
classifications as metadata for analysis throughout the network.
This idea has trust and privacy implications.
o Congestion Exposure [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: a bit that allows the content provider
to indicate whether higher bandwidth or lower latency is of
greater priority and allows 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 relying only on end-to-end protocols to
manage congestion.
o Flow Queue Controlled Delay (FQ-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
endpoints. Others aim to create "hop-by-hop" solutions, which could
be more aligned with how congestion is managed today but with greater
privacy implications.
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 sharing 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 categorization and on
providing this information to the protocols or endpoints. Completely
categorizing radio networks could be impossible due to their
complexity, but categorizing essential network properties could be
possible and valuable.
4. Transport Layer: Issues, Optimization, and Solutions
TCP has been the dominant transport protocol since TCP/IP replaced
the Network Control Protocol (NCP) 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.
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 the Stream Control
Transmission Protocol (SCTP) and Datagram Congestion Control Protocol
(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 IP Stack
Evolution program, and the first step in this program 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. For mostly competitive reasons, network
operators do not tend to reveal network information and so are
unlikely to donate this information freely to the IETF. The GSMA is
in a position to try to collect this data and anonymize it before
bringing it to IETF, which should alleviate the network operator
worries but still provide IETF with some usable data.
Although congestion is only detected when packet loss is encountered
and better methods based on detecting congestion would be beneficial,
a considerable amount of work has already been done on TCP,
especially innovation in bandwidth management and congestion control.
Furthermore, although the deficiencies of TCP are often considered
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 suggested that SPUD [SPUD] and
Information-Centric Networking (ICN) [RFC7476] may help here. Quick
UDP Internet Connection [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.
5. Application-Layer Optimization, 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 regarding their experiences running over mobile networks,
the quality of experience their users expect, and the content and
caching that providers would like to achieve by working with or using
the mobile network.
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 standards 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 centers to report issues that
are difficult to test for and resolve.
Content providers cited other common issues concerning data traffic
over mobile networks. Data subscription limits (known as "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 organization 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 near the user at the edge
of the mobile network. Placing caches at the edge of the mobile
network is a solution, but it requires standards developed by content
providers and mobile network operators. The IETF's CDN
Interconnection [CDNI] Working Group 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 the Chatham House Rule. The session
aimed to discuss regulatory and political issues, but not their worth
or need, and to understand the laws that exist and how technologists
can properly respond to them.
Mobile networks are regulated; compliance is mandatory and can incur
costs on the mobile network operator, while non-compliance can result
in service license revocation in some nations. Regulation does vary
geographically. Some regulations are court orders and others are
self-imposed regulations, for example, "block lists" of websites such
as the Internet Watch Foundation [IWF] list. 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 that 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 together 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.
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 for
information to be discovered and attributed to individual users.
o Minimum data only for collaborative work: User data, application
data, and network data all need protection, so new solutions
should use minimal 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 [SPROUT]: Researched at MIT, Sprout is a transport protocol
for applications that desire high throughput and low delay.
o PCC [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.
o CDNs and Caches: This suggests that 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 [BLIND_CACHING]: This is a proposal for caching of
encrypted content.
o CDN Improvements: This includes Keyless SSL and better CDN
placement.
o Mobile Throughput Guidance [MTG]: This is a mechanism and protocol
elements that allow the cellular network to provide near real-time
information on capacity available to the TCP server.
o One Bit for Latency / Bandwidth Trade-Off: This suggests
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 categorizations 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 behavior. Alternatively, an API
could provide the network with information on the data type,
allowing appropriate network management for that data type;
however, this method exposes privacy issues.
o Standard approach for the 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.
o Keyless SSL [KeylessSSL]: This 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 standardized in the
IETF. [LURK]
o Meaningful capacity sharing: This includes the ConEx [CONEX] work,
which exposes information about congestion to the network nodes.
o Hop-by-hop: Some suggestions offer hop-by-hop methods that allow
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 behavior. 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 within the IETF;
o reviews and comments on 3GPP perspective; and,
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 organizations. 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 that 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 Alternatives to
Content Classification for Operator Resource Deployment (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
discussions that had taken place within the workshop and highlighting
key areas to progress on. Key areas to progress on and an update on
their current status are as follows:
o The collection of usable 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 IP Stack Evolution program and
throughout transport-related IETF working groups such as the
Transport Area Working Group (TSVWG).
o The Mobile Throughput Guidance document [MTG] has entered into a
testing and data collection phase, although further advancements
in transport technologies (QUIC, among others) may have stalled
efforts in TCP-related proposals.
o Work on proposals for caching encrypted content continue, albeit
with some security flaws that proponents are working on further
proposals to fix. Most often, these are discussed within the IETF
HTTPbis Working Group.
o The Path Layer UDP Substrate (PLUS) BOF at IETF 96 in July 2016
did not result in the formation of a working group, as attendees
expressed concern on the privacy issues associated with the
proposed data-sharing possibilities of the shim layer.
o The Limited Use of Remote Keys (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 that 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.
It does not affect the security of the Internet, taken on its own.
10. IANA Considerations
This document has no IANA actions.
11. Informative References
[BLIND_CACHING]
Thomson, M., Eriksson, G., and C. Holmberg, "Caching
Secure HTTP Content using Blind Caches", Work in
Progress, draft-thomson-http-bc-01, October 2016.
[CDNI] IETF, "Content Delivery Networks Interconnection (cdni)",
<https://datatracker.ietf.org/wg/cdni/charter/>.
[CHATHAM_HOUSE_RULE]
Chatham House, "Chatham House Rule | Chatham House",
<https://www.chathamhouse.org/about/chatham-house-rule>.
[CONEX] IETF, "Congestion Exposure (conex) - Documents",
<https://datatracker.ietf.org/wg/conex/documents/>.
[EffectEncrypt]
Xiong, C. and M. Patel, "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]
Hoeiland-Joergensen, T., McKenney, P., Taht, D., Gettys,
J., and E. Dumazet, "FlowQueue-Codel", Work in Progress,
draft-hoeiland-joergensen-aqm-fq-codel-01, November 2014.
[GSMA] GSMA, "GSMA Homepage", <http://gsma.com>.
[IWF] IWF, "Internet Watch Foundation Homepage",
<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] Migault, D., Ma, K., Salz, R., Mishra, S., and O. Dios,
"LURK TLS/DTLS Use Cases", Work in Progress,
draft-mglt-lurk-tls-use-cases-02, June 2016.
[MARNEW] IAB, "Managing Radio Networks in an Encrypted World
(MaRNEW) Workshop 2015",
<https://www.iab.org/activities/workshops/marnew/>.
[MTG] Jain, A., Terzis, A., Flinck, H., Sprecher, N.,
Arunachalam, S., Smith, K., Devarapalli, V., and R. Yanai,
"Mobile Throughput Guidance Inband Signaling Protocol",
Work in Progress, draft-flinck-mobile-throughput-guidance-
04, March 2017.
[NETWORK_MANAGEMENT]
Smith, K., "Network management of encrypted traffic", Work
in Progress, draft-smith-encrypted-traffic-management-05,
May 2016.
[NOTE_WELL]
IETF, "IETF Note Well",
<https://www.ietf.org/about/note-well.html>.
[PCC] Dong, M., Li, Q., Zarchy, D., Brighten Godfrey, P., and M.
Schapira, "PCC: Re-architecting Congestion Control for
Consistent High Performance", Proceedings of the 12th
USENIX Symposium on Networked Systems Design and
Implementation (NSDI '15), USENIX Association, May 2015,
<https://www.usenix.org/system/files/conference/nsdi15/
nsdi15-paper-dong.pdf>.
[PCC-QOS] 3GPP, "Policy and charging control signalling flows and
Quality of Service (QoS) parameter mapping", 3GPP TS
29.213, version 15.3.0, Release 15, June 2018,
<http://www.3gpp.org/DynaReport/29213.htm>.
[Pew2014] Madden, M., "Public Perceptions of Privacy and Security in
the Post-Snowden Era", November 2014,
<http://www.pewinternet.org/2014/11/12/
public-privacy-perceptions/>.
[QUIC] Hamilton, R., Iyengar, J., Swett, I., and A. Wilk, "QUIC:
A UDP-Based Secure and Reliable Transport for HTTP/2",
Work in Progress, draft-tsvwg-quic-protocol-02, January
2016.
[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>.
[RFC8404] Moriarty, K., Ed. and A. Morton, Ed., "Effects of
Pervasive Encryption on Operators", RFC 8404,
DOI 10.17487/RFC8404, July 2018,
<https://www.rfc-editor.org/info/rfc8404>.
[SDO_3GPP] 3GPP, "3GPP Homepage", <http://www.3gpp.org/>.
[SPROUT] Winstein, K., Sivaraman, A., and H. Balakrishnan,
"Stochastic Forecasts Achieve High Throughput and Low
Delay over Cellular Networks", 10th USENIX Symposium on
Networked Systems Design and Implementation (NSDI
'13), USENIX Association, April 2013,
<https://www.usenix.org/system/files/conference/nsdi13/
nsdi13-final113.pdf>.
[SPUD] IETF, "Session Protocol for User Datagrams (spud)",
<https://datatracker.ietf.org/wg/spud/about/>.
[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 (tcpinc)",
<https://datatracker.ietf.org/wg/tcpinc/charter/>.
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
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
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, Vijay Gurbani, and Thomas Fossati, "The
security pendulum" 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 J. La Roche, "Use Cases for Communicating End-Points in
Mobile Network Middleboxes" at <https://www.iab.org/wp-content/
IAB-uploads/2015/08/MaRNEW_1_paper_12.pdf>
o Patrick McManus and Richard Barnes, "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 Goran 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, "Concept for Cooperative
Traffic Management" at <https://www.iab.org/wp-content/
IAB-uploads/2015/08/MaRNEW_1_paper_16.pdf>
o Gianpaolo Scassellati, "Vimpelcom Position paper for MaRNEW
Workshop" at <https://www.iab.org/wp-content/IAB-uploads/2015/09/
MaRNEW_1_paper_17.pdf>
o Mirja Kuhlewind, 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, Salvatore Loreto, and Robert Skog, "The needed
existence of PEP 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, "Security, Privacy, and Performance Considerations
for the Mobile Web" at <https://www.iab.org/wp-content/
IAB-uploads/2015/08/MaRNEW_1_paper_28.pdf>
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 Yves Hupe, Claude Rocray, and Mark Santelli, "Providing
Optimization of Encrypted HTTP Traffic" at <https://www.iab.org/
wp-content/IAB-uploads/2015/08/MaRNEW_1_paper_341.pdf>
o M. 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>
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.
Authors' Addresses
Natasha Rooney
GSMA
Email: nrooney@gsma.com
URI: https://gsma.com
Spencer Dawkins (editor)
Wonder Hamster
Email: spencerdawkins.ietf@gmail.com