draft-ietf-tsvwg-nqb-00.txt   draft-ietf-tsvwg-nqb-01.txt 
Transport Area Working Group G. White Transport Area Working Group G. White
Internet-Draft CableLabs Internet-Draft CableLabs
Intended status: Standards Track T. Fossati Intended status: Standards Track T. Fossati
Expires: May 7, 2020 ARM Expires: September 10, 2020 ARM
November 4, 2019 March 9, 2020
A Non-Queue-Building Per-Hop Behavior (NQB PHB) for Differentiated A Non-Queue-Building Per-Hop Behavior (NQB PHB) for Differentiated
Services Services
draft-ietf-tsvwg-nqb-00 draft-ietf-tsvwg-nqb-01
Abstract Abstract
This document specifies properties and characteristics of a Non- This document specifies properties and characteristics of a Non-
Queue-Building Per-Hop Behavior (NQB PHB). The purpose of this NQB Queue-Building Per-Hop Behavior (NQB PHB). The purpose of this NQB
PHB is to provide a separate queue that enables low latency and, when PHB is to provide a separate queue that enables low latency and, when
possible, low loss for application-limited traffic flows that would possible, low loss for application-limited traffic flows that would
ordinarily share a queue with capacity-seeking traffic. The PHB ordinarily share a queue with capacity-seeking traffic. This PHB is
provides low latency and, when possible, low loss without implemented without prioritization and without rate policing, making
prioritization and without rate policing, making it suitable for it suitable for environments where the use of either these features
environments where the use of either these features may be may be restricted. The NQB PHB has been developed primarily for use
restricted. The NQB PHB has been developed primarily for use by by access network segments, where queuing delays and queuing loss
access network segments, where queuing delays and queuing loss caused caused by Queue-Building protocols are manifested, but its use is not
by Queue-Building protocols are manifested, but its use is not
limited to such segments. In particular, applications to cable limited to such segments. In particular, applications to cable
broadband links and mobile network radio and core segments are broadband links and mobile network radio and core segments are
discussed. This document defines a standard Differentiated Services discussed. This document defines a standard Differentiated Services
Code Point (DSCP) to identify Non-Queue-Building flows. Code Point (DSCP) to identify Non-Queue-Building flows.
Status of This Memo Status of This Memo
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Copyright Notice Copyright Notice
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Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Requirements Language . . . . . . . . . . . . . . . . . . . . 3 2. Requirements Language . . . . . . . . . . . . . . . . . . . . 3
3. Overview: Non-Queue Building Flows . . . . . . . . . . . . . 3 3. Overview: Non-Queue-Building Flows . . . . . . . . . . . . . 3
4. DSCP Marking of NQB Traffic . . . . . . . . . . . . . . . . . 4 4. DSCP Marking of NQB Traffic . . . . . . . . . . . . . . . . . 4
5. Non Queue Building PHB Requirements . . . . . . . . . . . . . 5 5. Non-Queue-Building PHB Requirements . . . . . . . . . . . . . 5
6. Relationship to L4S . . . . . . . . . . . . . . . . . . . . . 6 6. Relationship to L4S . . . . . . . . . . . . . . . . . . . . . 6
7. Use Cases . . . . . . . . . . . . . . . . . . . . . . . . . . 6 7. Use Cases . . . . . . . . . . . . . . . . . . . . . . . . . . 6
7.1. DOCSIS Access Networks . . . . . . . . . . . . . . . . . 6 7.1. DOCSIS Access Networks . . . . . . . . . . . . . . . . . 6
7.2. Mobile Networks . . . . . . . . . . . . . . . . . . . . . 6 7.2. Mobile Networks . . . . . . . . . . . . . . . . . . . . . 6
7.3. WiFi Networks . . . . . . . . . . . . . . . . . . . . . . 7 7.3. WiFi Networks . . . . . . . . . . . . . . . . . . . . . . 7
8. Open Points . . . . . . . . . . . . . . . . . . . . . . . . . 7 8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 8
9. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 7 9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 8
10. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 8 10. Security Considerations . . . . . . . . . . . . . . . . . . . 8
11. Security Considerations . . . . . . . . . . . . . . . . . . . 8 11. Informative References . . . . . . . . . . . . . . . . . . . 9
12. Informative References . . . . . . . . . . . . . . . . . . . 8 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 10
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 9
1. Introduction 1. Introduction
This document defines a Differentiated Services (DS) per-hop behavior This document defines a Differentiated Services (DS) per-hop behavior
(PHB) called "Non-Queue-Building Per-Hop Behavior" (NQB PHB), which (PHB) called "Non-Queue-Building Per-Hop Behavior" (NQB PHB), which
is intended to enable networks to provide low latency and low loss is intended to enable networks to provide low latency and low loss
for traffic flows that are relatively low data rate and that do not for traffic flows that are relatively low data rate and that do not
themselves materially contribute to queueing delay and loss. Such themselves materially contribute to queueing delay and loss. Such
Non-Queue-Building flows (for example: interactive voice and video, Non-Queue-Building flows (for example: interactive voice and video,
gaming, machine to machine applications) are application limited gaming, machine to machine applications) are application limited
flows that are distinguished from traffic flows managed by an end-to- flows that are distinguished from traffic flows managed by an end-to-
end congestion control algorithm. end congestion control algorithm.
The vast majority of packets that are carried by broadband access The vast majority of packets that are carried by broadband access
networks are, in fact, managed by an end-to-end congestion control networks are, in fact, managed by an end-to-end congestion control
algorithm, such as Reno, Cubic or BBR. These congestion control algorithm, such as Reno, Cubic or BBR. These congestion control
algorithms attempt to seek the available capacity of the end-to-end algorithms attempt to seek the available capacity of the end-to-end
path (which can frequently be the access network link capacity), and path (which can frequently be the access network link capacity), and
in doing so generally overshoot the available capacity, causing a in doing so generally overshoot the available capacity, causing a
queue to build-up at the bottleneck link. This queue build up queue to build-up at the bottleneck link. This queue build up
results in queuing delay that the application experiences as variable results in queuing delay (variable latency) and possibly packet loss
latency, and may result in packet loss as well. that affects all of the applications that are sharing the bottleneck
link.
In contrast to traditional congestion-controlled applications, there In contrast to traditional congestion-controlled applications, there
are a variety of relatively low data rate applications that do not are a variety of relatively low data rate applications that do not
materially contribute to queueing delay and loss, but are nonetheless materially contribute to queueing delay and loss, but are nonetheless
subjected to it by sharing the same bottleneck link in the access subjected to it by sharing the same bottleneck link in the access
network. Many of these applications may be sensitive to latency or network. Many of these applications may be sensitive to latency or
latency variation, as well as packet loss, and thus produce a poor latency variation, as well as packet loss, and thus produce a poor
quality of experience in such conditions. quality of experience in such conditions.
Active Queue Management (AQM) mechanisms (such as PIE [RFC8033], Active Queue Management (AQM) mechanisms (such as PIE [RFC8033],
DOCSIS-PIE [RFC8034], or CoDel [RFC8289]) can improve the quality of DOCSIS-PIE [RFC8034], or CoDel [RFC8289]) can improve the quality of
experience for latency sensitive applications, but there are experience for latency sensitive applications, but there are
practical limits to the amount of improvement that can be achieved practical limits to the amount of improvement that can be achieved
without impacting the throughput of capacity-seeking applications without impacting the throughput of capacity-seeking applications,
when only a few of such flows are present. particularly when only a few of such flows are present.
The NQB PHB supports differentiating between these two classes of The NQB PHB supports differentiating between these two classes of
traffic in bottleneck links and queuing them separately in order that traffic in bottleneck links and queuing them separately in order that
both classes can deliver satisfactory quality of experience for their both classes can deliver satisfactory quality of experience for their
applications. applications.
2. Requirements Language 2. Requirements Language
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in BCP "OPTIONAL" in this document are to be interpreted as described in BCP
14 [RFC2119] [RFC8174] when, and only when, they appear in all 14 [RFC2119] [RFC8174] when, and only when, they appear in all
capitals, as shown here. capitals, as shown here.
3. Overview: Non-Queue Building Flows 3. Overview: Non-Queue-Building Flows
There are many applications that send traffic at relatively low data There are many applications that send traffic at relatively low data
rates and/or in a fairly smooth and consistent manner such that they rates and/or in a fairly smooth and consistent manner such that they
are highly unlikely to exceed the available capacity of the network are highly unlikely to exceed the available capacity of the network
path between source and sink. These applications do not make path between source and sink. These applications do not cause queues
extensive use of network buffers, but nonetheless can be subjected to to form in network buffers, but nonetheless can be subjected to
packet delay and delay variation as a result of sharing a network packet delay and delay variation as a result of sharing a network
buffer with those that do make use of them. Many of these buffer with applications that do cause queues. Many of these
applications are negatively affected by excessive packet delay and applications are negatively affected by excessive packet delay and
delay variation. Such applications are ideal candidates to be queued delay variation. Such applications are ideal candidates to be queued
separately from the capacity-seeking applications that are the cause separately from the capacity-seeking applications that are the cause
of queue buildup, latency and loss. of queue buildup, latency and loss.
These Non-queue-building (NQB) flows are typically UDP flows that These Non-queue-building (NQB) flows are typically UDP flows that
don't seek the capacity of the link (examples: online games, voice don't seek the capacity of the link (examples: online games, voice
chat, DNS lookups, real-time IoT analytics data). Here the data rate chat, DNS lookups, real-time IoT analytics data). Here the data rate
is essentially limited by the Application itself. In contrast, is limited by the Application itself rather than by network capacity
Queue-building (QB) flows include traffic which uses the Traditional - in many cases these applications only send a few packets per RTT.
TCP or QUIC, with BBR or other TCP congestion controllers. In contrast, Queue-building (QB) flows include traffic which uses the
Traditional TCP or QUIC, with BBR or other TCP congestion
controllers.
4. DSCP Marking of NQB Traffic
Applications that align with the above description of NQB behavior
SHOULD identify themselves to the network using a DiffServ Code Point
(DSCP) so that their packets can be queued separately from QB flows.
There are many application flows that fall very neatly into one or There are many application flows that fall very neatly into one or
the other of these categories, but there are also application flows the other of these categories, but there are also application flows
that may be in a gray area in between (e.g. they are NQB on higher- that may be in a gray area in between (e.g. they are NQB on higher-
speed links, but QB on lower-speed links). speed links, but QB on lower-speed links).
Editor's Note: Do we need to answer the following questions? How can If there is uncertainty as to whether an application's traffic aligns
an application determine whether it is queue building or not, given with the description of NQB behavior in the preceding section, the
that the sending application is generally not aware of the available application SHOULD NOT mark its traffic with the NQB DSCP. In such a
capacity of the path to the receiving endpoint? Even if the case, the application SHOULD instead implement a congestion control
application were to be aware of the capacity of the path, how could mechanism, for example as described in [RFC8085].
it be sure that the available capacity (considering other flows that
may be sharing the path) would be sufficient to result in the
application's traffic not causing a queue to form?
4. DSCP Marking of NQB Traffic
This document recommends a DiffServ Code Point (DSCP) of 0x2A to This document recommends a DSCP of 0x2A to identify packets of NQB
identify packets of NQB flows. (editor's note: this value is subject flows. (editor's note: this value is subject to change)
to change)
It is worthwhile to note that the NQB designation and marking is It is worthwhile to note that the NQB designation and marking is
intended to convey verifiable traffic behavior, not needs or wants. intended to convey verifiable traffic behavior, not needs or wants.
Also, it is important that incentives are aligned correctly, i.e. Also, it is important that incentives are aligned correctly, i.e.
that there is a benefit to the application in marking its packets that there is a benefit to the application in marking its packets
correctly, and no benefit to an application in intentionally correctly, and no benefit to an application in intentionally
mismarking its traffic. Thus, a useful property of nodes that mismarking its traffic. Thus, a useful property of nodes that
support separate queues for NQB and QB flows would be that for NQB support separate queues for NQB and QB flows would be that for NQB
flows, the NQB queue provides better performance than the QB queue; flows, the NQB queue provides better performance than the QB queue;
and for QB flows, the QB queue provides better performance than the and for QB flows, the QB queue provides better performance than the
NQB queue. By adhering to these principles, there is no incentive NQB queue. By adhering to these principles, there is no incentive
for senders to mismark their traffic as NQB, and further, any for senders to mismark their traffic as NQB, and further, any
mismarking can be identified by the network. mismarking can be identified by the network.
In contrast to the existing standard DSCPs, which are typically only In contrast to the existing standard DSCPs, which are typically only
meaningful within a DiffServ Domain (e.g. an AS or an enterprise meaningful within a DiffServ Domain (e.g. an AS or an enterprise
network), this DSCP is expected to be used end-to-end across the network), this DSCP is expected to be used end-to-end across the
Internet. Some network operators typically bleach (zero out) the Internet. Some network operators typically bleach (zero out) the
Diffserv field on ingress into their network [Custura], and in some DiffServ field on ingress into their network [Custura], and in some
cases apply their own DSCP for internal usage. Networks that support cases apply their own DSCP for internal usage. Networks that support
the NQB PHB SHOULD preserve the NQB DSCP when forwarding via an the NQB PHB SHOULD preserve the NQB DSCP when forwarding via an
interconnect from another network. interconnect from or to another network.
5. Non Queue Building PHB Requirements 5. Non-Queue-Building PHB Requirements
A node supporting the NQB PHB makes no guarantees on latency or data A node supporting the NQB PHB makes no guarantees on latency or data
rate for NQB marked flows, but instead aims to provide a bound on rate for NQB marked flows, but instead aims to provide a bound on
queuing delay for as many such marked flows as it can, and shed load queuing delay for as many such marked flows as it can, and shed load
when needed. when needed.
A node supporting the NQB PHB MUST provide a queue for non-queue- A node supporting the NQB PHB MUST provide a queue for non-queue-
building traffic separate from the queue used for queue-building building traffic separate from the queue used for queue-building
traffic. traffic.
skipping to change at page 5, line 40 skipping to change at page 5, line 42
marked traffic. marked traffic.
The NQB queue SHOULD have a buffer size that is significantly smaller The NQB queue SHOULD have a buffer size that is significantly smaller
than the buffer provided for QB traffic. than the buffer provided for QB traffic.
It is possible that due to an implementation error or It is possible that due to an implementation error or
misconfiguration, a QB flow would end up getting mismarked as NQB, or misconfiguration, a QB flow would end up getting mismarked as NQB, or
vice versa. In the case of an NQB flow that isn't marked as NQB and vice versa. In the case of an NQB flow that isn't marked as NQB and
ends up in the QB queue, it would only impact its own quality of ends up in the QB queue, it would only impact its own quality of
service, and so it seems to be of lesser concern. However, a QB flow service, and so it seems to be of lesser concern. However, a QB flow
that is mismarked as NQB would cause queuing delays for all of the that is mismarked as NQB would cause queuing delays and/or loss for
other flows that are sharing the NQB queue. all of the other flows that are sharing the NQB queue.
To prevent this situation from harming the performance of the real To prevent this situation from harming the performance of the real
NQB flows, network elements that support differentiating NQB traffic NQB flows, network elements that support differentiating NQB traffic
SHOULD (editor's note: SHOULD vs MUST is TBD) support a "traffic SHOULD (editor's note: SHOULD vs MUST is TBD) support a "traffic
protection" function that can identify QB flows that are mismarked as protection" function that can identify QB flows that are mismarked as
NQB, and reclassify those flows/packets to the QB queue. Such a NQB, and reclassify those flows/packets to the QB queue. Such a
function SHOULD be implemented in an objective and verifiable manner, function SHOULD be implemented in an objective and verifiable manner,
basing its decisions upon the behavior of the flow rather than on basing its decisions upon the behavior of the flow rather than on
application-layer constructs. One example algorithm can be found in application-layer constructs. One example algorithm can be found in
[I-D.briscoe-docsis-q-protection]. [I-D.briscoe-docsis-q-protection].
6. Relationship to L4S 6. Relationship to L4S
The dual-queue mechanism described in this draft is intended to be Traffic flows marked with the NQB DSCP as described in this draft are
compatible with [I-D.ietf-tsvwg-l4s-arch], with the result being that intended to be compatible with [I-D.ietf-tsvwg-l4s-arch], with the
NQB traffic and L4S traffic can share the low-latency queue in an L4S result being that NQB traffic and L4S traffic can share the low-
dual-queue node [I-D.ietf-tsvwg-aqm-dualq-coupled]. latency queue in an L4S dual-queue node
[I-D.ietf-tsvwg-aqm-dualq-coupled].
7. Use Cases 7. Use Cases
7.1. DOCSIS Access Networks 7.1. DOCSIS Access Networks
Residential cable broadband Internet services are commonly configured Residential cable broadband Internet services are commonly configured
with a single bottleneck link (the access network link) upon which with a single bottleneck link (the access network link) upon which
the service definition is applied. The service definition, typically the service definition is applied. The service definition, typically
an upstream/downstream data rate tuple, is implemented as a an upstream/downstream data rate tuple, is implemented as a
configured pair of rate shapers that are applied to the user's configured pair of rate shapers that are applied to the user's
traffic. In such networks, the quality of service that each traffic. In such networks, the quality of service that each
application receives, and as a result, the quality of experience that application receives, and as a result, the quality of experience that
it generates for the user is influenced by the characteristics of the it generates for the user is influenced by the characteristics of the
access network link. access network link.
To support the NQB PHB, cable broadband services MUST be configured To support the NQB PHB, cable broadband services MUST be configured
to provide a separate queue for NQB marked traffic. The NQB queue to provide a separate queue for NQB marked traffic. The NQB queue
MUST be configured to share the service's rate shaping bandwith with MUST be configured to share the service's rate shaping bandwidth with
the queue for QB traffic. the queue for QB traffic.
7.2. Mobile Networks 7.2. Mobile Networks
Historically, mobile networks have been configured to bundle all Historically, mobile networks have been configured to bundle all
flows to and from the Internet into a single "default" EPS bearer flows to and from the Internet into a single "default" EPS bearer
whose buffering characteristics are not compatible with low-latency whose buffering characteristics are not compatible with low-latency
traffic. The established behaviour is rooted partly in the desire to traffic. The established behaviour is rooted partly in the desire to
prioritise operators' voice services over competing over-the-top prioritise operators' voice services over competing over-the-top
services and partly in the fact that the addition of bearers was services and partly in the fact that the addition of bearers was
prohibitive due to expense. Of late, said consideration seems to prohibitive due to expense. Of late, said consideration seems to
have lost momentum (e.g., with the rise in Multi-RAB (Radio Access have lost momentum (e.g., with the rise in Multi-RAB (Radio Access
Bearer) devices) and the incentives might now be aligned towards Bearer) devices) and the incentives might now be aligned towards
allowing a more suitable treatment of Internet real-time flows. allowing a more suitable treatment of Internet real-time flows.
To support the NQB PHB, the mobile network MUST be configured to give To support the NQB PHB, the mobile network SHOULD be configured to
UEs a dedicated, low-latency, non-GBR, EPS bearer, e.g. one with QCI give UEs a dedicated, low-latency, non-GBR, EPS bearer, e.g. one with
7, in addition to the default EPS bearer; or a Data Radio Bearer with QCI 7, in addition to the default EPS bearer; or a Data Radio Bearer
5QI 7 in a 5G system (see Table 5.7.4-1: Standardized 5QI to QoS with 5QI 7 in a 5G system (see Table 5.7.4-1: Standardized 5QI to QoS
characteristics mapping in [SA-5G]). characteristics mapping in [SA-5G]).
A packet carrying the NQB DSCP SHOULD be routed through the dedicated A packet carrying the NQB DSCP SHOULD be routed through the dedicated
low-latency EPS bearer. A packet that has no associated NQB marking low-latency EPS bearer. A packet that has no associated NQB marking
SHOULD be routed through the default EPS bearer. SHOULD be routed through the default EPS bearer.
7.3. WiFi Networks 7.3. WiFi Networks
WiFi networking equipment compliant with 802.11e generally supports WiFi networking equipment compliant with 802.11e generally supports
either four or eight transmit queues and four sets of associated EDCA either four or eight transmit queues and four sets of associated
parameters (corresponding to the four WiFi Multimedia Access Enhanced Multimedia Distributed Control Access (EDCA) parameters
Categories) that are used to enable differentiated media access (corresponding to the four WiFi Multimedia (WMM) Access Categories)
characteristics. Implementations typically utilize the IP DSCP field that are used to enable differentiated media access characteristics.
to select a transmit queue, but should be considered as Non- Implementations typically utilize the IP DSCP field to select a
Differentiated Services-Compliant Nodes as described in Section 4 of transmit queue, but should be considered as Non-Differentiated
[RFC2475]. As a result this document discusses interoperability with Services-Compliant Nodes as described in Section 4 of [RFC2475]
WiFi networks, as opposed to PHB compliance. because this transmit queue selection is a local implementation
characteristic that is not part of a consistently operated DiffServ
domain or region. As a result this document discusses
interoperability with WiFi networks, as opposed to PHB compliance.
As discussed in [RFC8325], most existing implementations use a As discussed in [RFC8325], most existing WiFi implementations use a
default DSCP to User Priority mapping that utilizes the most default DSCP to User Priority mapping that utilizes the most
significant three bits of the DiffServ Field to select "User significant three bits of the DiffServ Field to select "User
Priority" which is then mapped to the four WMM Access Categories. In Priority" which is then mapped to the four WMM Access Categories. In
order to increase the likelihood that NQB traffic is provided a order to increase the likelihood that NQB traffic is provided a
separate queue from QB traffic in existing WiFi equipment, the 0x2A separate queue from QB traffic in existing WiFi equipment, the 0x2A
codepoint is preferred for NQB. This would map NQB to UP_5 which is codepoint is preferred for NQB. This would map NQB to UP_5 which is
in the "Video" Access Category. in the "Video" Access Category. Similarly, systems that utilize
[RFC8325], SHOULD map the NQB codepoint to UP_5 in the "Video" Access
Systems that utilize [RFC8325], SHOULD map the NQB codepoint to UP_5 Category.
in the "Video" Access Category.
In order to preserve the incentives principle, WiFi systems SHOULD
configure the EDCA parameters for the Video Access Category to match
those of the Best Effort Access Category.
8. Open Points
o Traffic Protection: SHOULD or MUST? While the DSCP to User Priority mapping can enable WiFi systems to
support the NQB PHB requirement for segregated queuing, many
currently deployed WiFi systems may not be capable of supporting the
remaining NQB PHB requirements in Section 5. This is discussed
further below.
o Traffic Protection: what are the detailed requirements? Existing WiFi devices are unlikely to support a traffic protection
algorithm, so traffic mismarked as NQB is not likely to be detected
and remedied by such devices.
o DSCP value vis a vis WMM: VideoAC or BestEffortAC? Furthermore, in their default configuration, existing WiFi devices
utilize EDCA parameters that result in statistical prioritization of
the "Video" Access Category above the "Best Effort" Access Category.
If left unchanged, this would violate the NQB PHB requirement for
equal prioritization, and could erode the principle of alignment of
incentives. In order to preserve the incentives principle, WiFi
systems SHOULD configure the EDCA parameters for the Video Access
Category to match those of the Best Effort Access Category.
o Are there hidden requirements in Section 9 of the individual In cases where a network operator is delivering traffic into an
draft? unmanaged WiFi network outside of their control (e.g. a residential
ISP delivering traffic to a customer's home network), the network
operator should presume that the existing WiFi equipment does not
support the safeguards that are provided by the NQB PHB requirements,
and thus should take precautions to prevent issues. In these
situations, the operator SHOULD deploy a policing function on NQB
marked traffic that minimizes the potential for starvation of traffic
marked Default, for example by limiting the rate of such traffic to a
set fraction of the customer's service rate.
o Is more discussion needed around applicability in order to give As an additional safeguard, and to prevent the inadvertent
guidance to application devs? introduction of problematic traffic into unmanaged WiFi networks,
network equipment that is intended to deliver traffic into unmanaged
WiFi networks (e.g. an access network gateway for a residential ISP)
MUST by default remap the NQB DSCP to Default. Such equipment MUST
support the ability to configure the remapping, so that (when
appropriate safeguards are in place) traffic can be delivered as NQB-
marked.
9. Acknowledgements 8. Acknowledgements
Thanks to Bob Briscoe, Greg Skinner, Toke Hoeiland-Joergensen, Luca Thanks to Bob Briscoe, Greg Skinner, Toke Hoeiland-Joergensen, Luca
Muscariello, David Black, Sebastian Moeller, Ruediger Geib, Jerome Muscariello, David Black, Sebastian Moeller, Ruediger Geib, Jerome
Henry, Steven Blake, Jonathan Morton, Roland Bless, Kevin Smith, Henry, Steven Blake, Jonathan Morton, Roland Bless, Kevin Smith,
Martin Dolly, and Kyle Rose for their review comments. Martin Dolly, and Kyle Rose for their review comments.
10. IANA Considerations 9. IANA Considerations
This draft proposes the registration of a standardized DSCP = 0x2A to This draft proposes the registration of a standardized DSCP = 0x2A to
denote Non-Queue-Building behavior. denote Non-Queue-Building behavior.
11. Security Considerations 10. Security Considerations
There is no incentive for an application to mismark its packets as There is no incentive for an application to mismark its packets as
NQB (or vice versa). If a queue-building flow were to mark its NQB (or vice versa). If a queue-building flow were to mark its
packets as NQB, it could experience excessive packet loss (in the packets as NQB, it could experience excessive packet loss (in the
case that traffic-protection is not supported by a node) or it could case that traffic protection is not supported by a node) or it could
receive no benefit (in the case that traffic-protection is receive no benefit (in the case that traffic protection is
supported). If a non-queue-building flow were to fail to mark its supported). If a non-queue-building flow were to fail to mark its
packets as NQB, it could suffer the latency and loss typical of packets as NQB, it could suffer the latency and loss typical of
sharing a queue with capacity seeking traffic. sharing a queue with capacity seeking traffic.
The NQB signal is not integrity protected and could be flipped by an The NQB signal is not integrity protected and could be flipped by an
on-path attacker. This might negatively affect the QoS of the on-path attacker. This might negatively affect the QoS of the
tampered flow. tampered flow.
12. Informative References 11. Informative References
[Custura] Custura, A., Venne, A., and G. Fairhurst, "Exploring DSCP [Custura] Custura, A., Venne, A., and G. Fairhurst, "Exploring DSCP
modification pathologies in mobile edge networks", TMA , modification pathologies in mobile edge networks", TMA ,
2017. 2017.
[I-D.briscoe-docsis-q-protection] [I-D.briscoe-docsis-q-protection]
Briscoe, B. and G. White, "Queue Protection to Preserve Briscoe, B. and G. White, "Queue Protection to Preserve
Low Latency", draft-briscoe-docsis-q-protection-00 (work Low Latency", draft-briscoe-docsis-q-protection-00 (work
in progress), July 2019. in progress), July 2019.
[I-D.ietf-tsvwg-aqm-dualq-coupled] [I-D.ietf-tsvwg-aqm-dualq-coupled]
Schepper, K., Briscoe, B., and G. White, "DualQ Coupled Schepper, K., Briscoe, B., and G. White, "DualQ Coupled
AQMs for Low Latency, Low Loss and Scalable Throughput AQMs for Low Latency, Low Loss and Scalable Throughput
(L4S)", draft-ietf-tsvwg-aqm-dualq-coupled-10 (work in (L4S)", draft-ietf-tsvwg-aqm-dualq-coupled-10 (work in
progress), July 2019. progress), July 2019.
[I-D.ietf-tsvwg-l4s-arch] [I-D.ietf-tsvwg-l4s-arch]
Briscoe, B., Schepper, K., Bagnulo, M., and G. White, "Low Briscoe, B., Schepper, K., Bagnulo, M., and G. White, "Low
Latency, Low Loss, Scalable Throughput (L4S) Internet Latency, Low Loss, Scalable Throughput (L4S) Internet
Service: Architecture", draft-ietf-tsvwg-l4s-arch-04 (work Service: Architecture", draft-ietf-tsvwg-l4s-arch-05 (work
in progress), July 2019. in progress), February 2020.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997, DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/info/rfc2119>. <https://www.rfc-editor.org/info/rfc2119>.
[RFC2475] Blake, S., Black, D., Carlson, M., Davies, E., Wang, Z., [RFC2475] Blake, S., Black, D., Carlson, M., Davies, E., Wang, Z.,
and W. Weiss, "An Architecture for Differentiated and W. Weiss, "An Architecture for Differentiated
Services", RFC 2475, DOI 10.17487/RFC2475, December 1998, Services", RFC 2475, DOI 10.17487/RFC2475, December 1998,
<https://www.rfc-editor.org/info/rfc2475>. <https://www.rfc-editor.org/info/rfc2475>.
skipping to change at page 9, line 22 skipping to change at page 9, line 50
Lightweight Control Scheme to Address the Bufferbloat Lightweight Control Scheme to Address the Bufferbloat
Problem", RFC 8033, DOI 10.17487/RFC8033, February 2017, Problem", RFC 8033, DOI 10.17487/RFC8033, February 2017,
<https://www.rfc-editor.org/info/rfc8033>. <https://www.rfc-editor.org/info/rfc8033>.
[RFC8034] White, G. and R. Pan, "Active Queue Management (AQM) Based [RFC8034] White, G. and R. Pan, "Active Queue Management (AQM) Based
on Proportional Integral Controller Enhanced PIE) for on Proportional Integral Controller Enhanced PIE) for
Data-Over-Cable Service Interface Specifications (DOCSIS) Data-Over-Cable Service Interface Specifications (DOCSIS)
Cable Modems", RFC 8034, DOI 10.17487/RFC8034, February Cable Modems", RFC 8034, DOI 10.17487/RFC8034, February
2017, <https://www.rfc-editor.org/info/rfc8034>. 2017, <https://www.rfc-editor.org/info/rfc8034>.
[RFC8085] Eggert, L., Fairhurst, G., and G. Shepherd, "UDP Usage
Guidelines", BCP 145, RFC 8085, DOI 10.17487/RFC8085,
March 2017, <https://www.rfc-editor.org/info/rfc8085>.
[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
May 2017, <https://www.rfc-editor.org/info/rfc8174>. May 2017, <https://www.rfc-editor.org/info/rfc8174>.
[RFC8289] Nichols, K., Jacobson, V., McGregor, A., Ed., and J. [RFC8289] Nichols, K., Jacobson, V., McGregor, A., Ed., and J.
Iyengar, Ed., "Controlled Delay Active Queue Management", Iyengar, Ed., "Controlled Delay Active Queue Management",
RFC 8289, DOI 10.17487/RFC8289, January 2018, RFC 8289, DOI 10.17487/RFC8289, January 2018,
<https://www.rfc-editor.org/info/rfc8289>. <https://www.rfc-editor.org/info/rfc8289>.
[RFC8325] Szigeti, T., Henry, J., and F. Baker, "Mapping Diffserv to [RFC8325] Szigeti, T., Henry, J., and F. Baker, "Mapping Diffserv to
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