QoS

This document describes the L4S architecture, which enables Internet applications to achieve low queuing latency, low congestion loss, and scalable throughput control. L4S is based on the insight that the root cause of queuing delay is in the capacity-seeking congestion controllers of senders, not in the queue itself. With the L4S architecture, all Internet applications could (but do not have to) transition away from congestion control algorithms that cause substantial queuing delay and instead adopt a new class of congestion controls that can seek capacity with very little queuing. These are aided by a modified form of Explicit Congestion Notification (ECN) from the network. With this new architecture, applications can have both low latency and high throughput.

The architecture primarily concerns incremental deployment. It defines mechanisms that allow the new class of L4S congestion controls to coexist with 'Classic' congestion controls in a shared network. The aim is for L4S latency and throughput to be usually much better (and rarely worse) while typically not impacting Classic performance.

This specification defines the protocol to be used for a new network service called Low Latency, Low Loss, and Scalable throughput (L4S). L4S uses an Explicit Congestion Notification (ECN) scheme at the IP layer that is similar to the original (or 'Classic') ECN approach, except as specified within. L4S uses 'Scalable' congestion control, which induces much more frequent control signals from the network, and it responds to them with much more fine-grained adjustments so that very low (typically sub-millisecond on average) and consistently low queuing delay becomes possible for L4S traffic without compromising link utilization. Thus, even capacity-seeking (TCP-like) traffic can have high bandwidth and very low delay at the same time, even during periods of high traffic load.

The L4S identifier defined in this document distinguishes L4S from 'Classic' (e.g., TCP-Reno-friendly) traffic. Then, network bottlenecks can be incrementally modified to distinguish and isolate existing traffic that still follows the Classic behaviour, to prevent it from degrading the low queuing delay and low loss of L4S traffic. This Experimental specification defines the rules that L4S transports and network elements need to follow, with the intention that L4S flows neither harm each other's performance nor that of Classic traffic. It also suggests open questions to be investigated during experimentation. Examples of new Active Queue Management (AQM) marking algorithms and new transports (whether TCP-like or real time) are specified separately.

This specification defines a framework for coupling the Active Queue Management (AQM) algorithms in two queues intended for flows with different responses to congestion. This provides a way for the Internet to transition from the scaling problems of standard TCP-Reno-friendly ('Classic') congestion controls to the family of 'Scalable' congestion controls. These are designed for consistently very low queuing latency, very low congestion loss, and scaling of per-flow throughput by using Explicit Congestion Notification (ECN) in a modified way. Until the Coupled Dual Queue (DualQ), these Scalable L4S congestion controls could only be deployed where a clean-slate environment could be arranged, such as in private data centres.

This specification first explains how a Coupled DualQ works. It then gives the normative requirements that are necessary for it to work well. All this is independent of which two AQMs are used, but pseudocode examples of specific AQMs are given in appendices.

The Measuring Network Quality for End-Users workshop was held virtually by the Internet Architecture Board (IAB) on September 14-16, 2021. This report summarizes the workshop, the topics discussed, and some preliminary conclusions drawn at the end of the workshop.

Note that this document is a report on the proceedings of the workshop. The views and positions documented in this report are those of the workshop participants and do not necessarily reflect IAB views and positions.

This is a position paper. It documents the author's personal views on how Quality of Service (QoS) capabilities ought to be accommodated in Information-Centric Networking (ICN) protocols like Content-Centric Networking (CCNx) or Named Data Networking (NDN), which employ flow-balanced Interest/Data exchanges and hop-by-hop forwarding state as their fundamental machinery. It argues that such protocols demand a substantially different approach to QoS from that taken in TCP/IP and proposes specific design patterns to achieve both classification and differentiated QoS treatment on both a flow and aggregate basis. It also considers the effect of caches in addition to memory, CPU, and link bandwidth as resources that should be subject to explicitly unfair resource allocation. The proposed methods are intended to operate purely at the network layer, providing the primitives needed to achieve transport- and higher-layer QoS objectives. It explicitly excludes any discussion of Quality of Experience (QoE), which can only be assessed and controlled at the application layer or above.

This document is not a product of the IRTF Information-Centric Networking Research Group (ICNRG) but has been through formal Last Call and has the support of the participants in the research group for publication as an individual submission.

This memo describes an application-level protocol for the communication of end-to-end QoS compliance information based on the HyperText Transfer Protocol (HTTP) and the Session Description Protocol (SDP). The Quality for Service (Q4S) protocol provides a mechanism to negotiate and monitor latency, jitter, bandwidth, and packet loss, and to alert whenever one of the negotiated conditions is violated.

Implementation details on the actions to be triggered upon reception/detection of QoS alerts exchanged by the protocol are out of scope of this document; it is either application dependent (e.g., act to increase quality or reduce bit-rate) or network dependent (e.g., change connection's quality profile).

This protocol specification is the product of research conducted over a number of years; it is presented here as a permanent record and to offer a foundation for future similar work. It does not represent a standard protocol and does not have IETF consensus.

This document describes methods of carrying Key Performance Indicators (KPIs) using the Network Service Header (NSH). These methods may be used, for example, to monitor latency and QoS marking to identify problems on some links or service functions.

This document describes open research challenges for network virtualization. Network virtualization is following a similar path as previously taken by cloud computing. Specifically, cloud computing popularized migration of computing functions (e.g., applications) and storage from local, dedicated, physical resources to remote virtual functions accessible through the Internet. In a similar manner, network virtualization is encouraging migration of networking functions from dedicated physical hardware nodes to a virtualized pool of resources. However, network virtualization can be considered to be a more complex problem than cloud computing as it not only involves virtualization of computing and storage functions but also involves abstraction of the network itself. This document describes current research and engineering challenges in network virtualization including the guarantee of quality of service, performance improvement, support for multiple domains, network slicing, service composition, device virtualization, privacy and security, separation of control concerns, network function placement, and testing. In addition, some proposals are made for new activities in the IETF and IRTF that could address some of these challenges. This document is a product of the Network Function Virtualization Research Group (NFVRG).

Congestion Exposure (ConEx) is a mechanism by which senders inform the network about the congestion encountered by packets earlier in the same flow. This document specifies an IPv6 destination option that is capable of carrying ConEx markings in IPv6 datagrams.

This memo defines a metric for one-way delay of packets across Internet paths. It builds on notions introduced and discussed in the IP Performance Metrics (IPPM) Framework document, RFC 2330; the reader is assumed to be familiar with that document. This memo makes RFC 2679 obsolete.

This memo defines a metric for one-way loss of packets across Internet paths. It builds on notions introduced and discussed in the IP Performance Metrics (IPPM) Framework document, RFC 2330; the reader is assumed to be familiar with that document. This memo makes RFC 2680 obsolete.

This document describes an abstract mechanism by which senders inform the network about the congestion recently encountered by packets in the same flow. Today, network elements at any layer may signal congestion to the receiver by dropping packets or by Explicit Congestion Notification (ECN) markings, and the receiver passes this information back to the sender in transport-layer feedback. The mechanism described here enables the sender to also relay this congestion information back into the network in-band at the IP layer, such that the total amount of congestion from all elements on the path is revealed to all IP elements along the path, where it could, for example, be used to provide input to traffic management. This mechanism is called Congestion Exposure, or ConEx. The companion document, "Congestion Exposure (ConEx) Concepts and Use Cases" (RFC 6789), provides the entry point to the set of ConEx documentation.

This document provides guidelines for achieving end-to-end Quality of Service (QoS) in a Proxy Mobile IPv6 (PMIPv6) domain where the access network is based on IEEE 802.11. RFC 7222 describes QoS negotiation between a Mobile Access Gateway (MAG) and Local Mobility Anchor (LMA) in a PMIPv6 mobility domain. The negotiated QoS parameters can be used for QoS policing and marking of packets to enforce QoS differentiation on the path between the MAG and LMA. IEEE 802.11 and Wi-Fi Multimedia - Admission Control (WMM-AC) describe methods for QoS negotiation between a Wi-Fi Station (MN in PMIPv6 terminology) and an Access Point. This document provides a mapping between the above two sets of QoS procedures and the associated QoS parameters. This document is intended to be used as a companion document to RFC 7222 to enable implementation of end-to-end QoS.

This specification defines a new mobility option, the Quality-of- Service (QoS) option, for Proxy Mobile IPv6. This option can be used by the local mobility anchor and the mobile access gateway for negotiating Quality-of-Service parameters for a mobile node's IP flows. The negotiated QoS parameters can be used for QoS policing and marking of packets to enforce QoS differentiation on the path between the local mobility anchor and the mobile access gateway. Furthermore, making QoS parameters available on the mobile access gateway enables mapping of these parameters to QoS rules that are specific to the access technology and allows those rules to be enforced on the access network using access-technology-specific approaches.

The RTP Control Protocol (RTCP) is used in conjunction with the Real-time Transport Protocol (RTP) to provide a variety of short-term and long-term reception statistics. The available reporting may include aggregate information across longer periods of time as well as individual packet reporting. This document specifies a report computing the bytes discarded from the de-jitter buffer after successful reception.

This document provides recommendations of best current practice for dropping or marking packets using any active queue management (AQM) algorithm, including Random Early Detection (RED), BLUE, Pre- Congestion Notification (PCN), and newer schemes such as CoDel (Controlled Delay) and PIE (Proportional Integral controller Enhanced). We give three strong recommendations: (1) packet size should be taken into account when transports detect and respond to congestion indications, (2) packet size should not be taken into account when network equipment creates congestion signals (marking, dropping), and therefore (3) in the specific case of RED, the byte- mode packet drop variant that drops fewer small packets should not be used. This memo updates RFC 2309 to deprecate deliberate preferential treatment of small packets in AQM algorithms.

This document defines an RTP Control Protocol (RTCP) Extended Report (XR) block that allows the reporting of de-jitter buffer metrics for a range of RTP applications.

The IPv6 protocol includes a flow label in every packet header, but this field is not used in practice. This paper describes the flow label standard and discusses the implementation issues that it raises. It then describes various published proposals for using the flow label and shows that most of them are inconsistent with the standard. Methods to address this problem are briefly reviewed. We also question whether the standard should be revised. This document is not an Internet Standards Track specification; it is published for informational purposes.

This document describes the framework, messages, and procedures for the Diameter Quality-of-Service (QoS) application. The Diameter QoS application allows network elements to interact with Diameter servers when allocating QoS resources in the network. In particular, two modes of operation, namely "Pull" and "Push", are defined. [STANDARDS TRACK]

This document defines a number of Diameter attribute-value pairs (AVPs) for traffic classification with actions for filtering and Quality of Service (QoS) treatment. These AVPs can be used in existing and future Diameter applications where permitted by the Augmented Backus-Naur Form (ABNF) specification of the respective Diameter command extension policy. [STANDARDS-TRACK]

This document defines a number of Quality of Service (QoS) parameters that can be reused for conveying QoS information within Diameter.

The defined QoS information includes data traffic parameters for describing a token bucket filter, a bandwidth parameter, and a per-hop behavior class object. [STANDARDS-TRACK]

In this document, we describe the applicability of the IP Flow Information eXport (IPFIX) protocol for a variety of applications. We show how applications can use IPFIX, describe the relevant Information Elements (IEs) for those applications, and present opportunities and limitations of the protocol. Furthermore, we describe relations of the IPFIX framework to other architectures and frameworks. This memo provides information for the Internet community.

This document describes a method to inform Real-time Transport Protocol (RTP) clients when RTP packets are transmitted at a time other than their 'nominal' transmission time. It also provides a mechanism to provide improved inter-arrival jitter reports from the clients, that take into account the reported transmission times. [STANDARDS-TRACK]

The offer/answer model for the Session Description Protocol (SDP) assumes that endpoints somehow establish the Quality of Service (QoS) required for the media streams they establish. Endpoints in closed environments typically agree out-of-band (e.g., using configuration information) regarding which QoS mechanism to use. However, on the Internet, there is more than one QoS service available. Consequently, there is a need for a mechanism to negotiate which QoS mechanism to use for a particular media stream. This document defines such a mechanism. [STANDARDS-TRACK]

This document presents some observations on "simple best-effort traffic", defined loosely for the purposes of this document as Internet traffic that is not covered by Quality of Service (QOS) mechanisms, congestion-based pricing, cost-based fairness, admissions control, or the like. One observation is that simple best-effort traffic serves a useful role in the Internet, and is worth keeping. While differential treatment of traffic can clearly be useful, we believe such mechanisms are useful as *adjuncts* to simple best- effort traffic, not as *replacements* of simple best-effort traffic. A second observation is that for simple best-effort traffic, some form of rough flow-rate fairness is a useful goal for resource allocation, where "flow-rate fairness" is defined by the goal of equal flow rates for different flows over the same path. This memo provides information for the Internet community.

This document provides recommendations for jittering (randomly modifying timing) of control traffic transmissions in Mobile Ad hoc NETwork (MANET) routing protocols to reduce the probability of transmission collisions. This memo provides information for the Internet community.

This memo offers non-normative implementation guidance for the Real-time Protocol (RTP) MIDI (Musical Instrument Digital Interface) payload format. The memo presents its advice in the context of a network musical performance application. In this application two musicians, located in different physical locations, interact over a network to perform as they would if located in the same room. Underlying the performances are RTP MIDI sessions over unicast UDP. Algorithms for sending and receiving recovery journals (the resiliency structure for the payload format) are described in detail. Although the memo focuses on network musical performance, the presented implementation advice is relevant to other RTP MIDI applications. [STANDARDS-TRACK]

This memo defines a Media Delivery Index (MDI) measurement that can be used as a diagnostic tool or a quality indicator for monitoring a network intended to deliver applications such as streaming media, MPEG video, Voice over IP, or other information sensitive to arrival time and packet loss. It provides an indication of traffic jitter, a measure of deviation from nominal flow rates, and a data loss at-a-glance measure for a particular flow. For instance, the MDI may be used as a reference in characterizing and comparing networks carrying UDP streaming media. This memo provides information for the Internet community.

This document updates RFC 3312, which defines the framework for preconditions in SIP. We provide guidelines for authors of new precondition types and describe how to use SIP preconditions in situations that involve session mobility. [STANDARDS-TRACK]

This document discusses IAB concerns about effective end-to-end congestion control for best-effort voice traffic in the Internet. These concerns have to do with fairness, user quality, and with the dangers of congestion collapse. The concerns are particularly relevant in light of the absence of a widespread Quality of Service (QoS) deployment in the Internet, and the likelihood that this situation will not change much in the near term. This document is not making any recommendations about deployment paths for Voice over Internet Protocol (VoIP) in terms of QoS support, and is not claiming that best-effort service can be relied upon to give acceptable performance for VoIP. We are merely observing that voice traffic is occasionally deployed as best-effort traffic over some links in the Internet, that we expect this occasional deployment to continue, and that we have concerns about the lack of effective end-to-end congestion control for this best-effort voice traffic. This memo provides information for the Internet community.

The purpose of this document is to define an information model to describe the quality of service (QoS) mechanisms inherent in different network devices, including hosts. Broadly speaking, these mechanisms describe the properties common to selecting and conditioning traffic through the forwarding path (datapath) of a network device. This selection and conditioning of traffic in the datapath spans both major QoS architectures: Differentiated Services and Integrated Services. This document should be used with the QoS Policy Information Model (QPIM) to model how policies can be defined to manage and configure the QoS mechanisms (i.e., the classification, marking, metering, dropping, queuing, and scheduling functionality) of devices. Together, these two documents describe how to write QoS policy rules to configure and manage the QoS mechanisms present in the datapaths of devices. This document, as well as QPIM, are information models. That is, they represent information independent of a binding to a specific type of repository

This document presents an object-oriented information model for representing Quality of Service (QoS) network management policies. This document is based on the IETF Policy Core Information Model and its extensions. It defines an information model for QoS enforcement for differentiated and integrated services using policy. It is important to note that this document defines an information model, which by definition is independent of any particular data storage mechanism and access protocol.

This document describes the need for QoS and media authorization and

defines a SIP extension that can be used to integrate QoS admission

control with call signaling and help guard against denial of service

attacks. The use of this extension is only applicable in

administrative domains, or among federations of administrative

domains with previously agreed-upon policies, where both the SIP

proxy authorizing the QoS, and the policy control of the underlying

network providing the QoS belong to that administrative domain or

federation of domains.

This document defines a generic framework for preconditions which is

extensible through IANA registration. This document also discusses

how network quality of service can be made a precondition to

establishment of sessions initiated by the Session Initiation

Protocol (SIP). These preconditions require that the participant

reserve network resources before continuing with the session. We do

not define new quality of service reservation mechanisms; these

preconditions simply require a participant to use existing resource

reservation mechanisms before beginning the session

This document describes policy-based accounting which is an approach

to provide flexibility to accounting architectures. Accounting

policies describe the configuration of an accounting architecture in

a standardized way. They are used to instrument the accounting

architecture and can be exchanged between AAA entities in order to

share configuration information.

This document describes building blocks and message sequences for

policy-based accounting in the generic AAA architecture [RFC2903].

Examples are given for the usage of accounting policies in different

scenarios. Furthermore it is shown how accounting components can be

integrated into the AAA authorization framework [RFC2904]. This

document does not propose a language for the description of

accounting policies. It is rather assumed that a suitable policy

language can be chosen from existing or upcoming standards.

The guiding principles in the design of IP network management were

simplicity and no centralized control. The best effort service

paradigm was a result of the original management principles and the

other way around. New methods to distinguish the service given to

one set of packets or flows relative to another are well underway.

However, as IP networks evolve the management approach of the past

may not apply to the QoS-capable network envisioned by some for the

future. We examine some of the areas of impact that QoS is likely

to have on management and look at some questions that remain to be

addressed.

In IP access networks that support host mobility, the routing paths

between the host and the network may change frequently and rapidly.

In some cases, the host may establish certain routing-related

services on subnets that are left behind when the host moves.

Examples of such services are AAA, header compression, and QoS. In

order for the host to obtain those services on the new subnet, the

host must explicitly re-establish the service by performing the

necessary signaling flows from scratch. In some cases, this process

would considerably slow the process of establishing the mobile host

on the new subnet. An alternative is to transfer information on the

existing state associated with these services, or context, to the

new subnet, a process called 'context transfer'. This document

discusses the desirability of context transfer for facilitating

seamless IP mobility.

This document describes the General Switch Management Protocol Version 3 (GSMPv3). The GSMPv3 is an asymmetric protocol that allows one or more external switch controllers to establish and maintain the state of a label switch such as, an ATM, frame relay or MPLS switch. The GSMPv3 allows control of both unicast and multicast switch connection state as well as control of switch system resources and QoS features. [STANDARDS-TRACK]

This document highlights the outstanding architectural issues relating to the deployment and use of QoS mechanisms within internet networks, noting those areas where further standards work may assist with the deployment of QoS internets. This document is the outcome of a collaborative exercise on the part of the Internet Architecture Board. This memo provides information for the Internet community.

This memo describes extensions to the OSPF protocol to support QoS routes. The focus of this document is on the algorithms used to compute QoS routes and on the necessary modifications to OSPF to support this function, e.g., the information needed, its format, how it is distributed, and how it is used by the QoS path selection process. This memo defines an Experimental Protocol for the Internet community.

This document describes some of the QoS-based routing issues and requirements, and proposes a framework for QoS-based routing in the Internet. This memo provides information for the Internet community. It does not specify an Internet standard of any kind.

This memo discusses Flow Attribute Notification Protocol (FANP), which is a protocol between neighbor nodes for the management of cut-through packet forwarding functionalities. This memo provides information for the Internet community. This memo does not specify an Internet standard of any kind.

This document specifies the protocol between the switch Connection Control Entity (CCE) and the external FAS. This memo provides information for the Internet community. This memo does not specify an Internet standard of any kind.

This memo describes a working implementation which enables applications to directly invoke ATM services in the following environments: ATM to internet, internet to ATM, and internet to internet across ATM. This memo provides information for the Internet community. This memo does not specify an Internet standard of any kind.

This memo argues that jitter control is not required for networks to support isochronous applications. This memo provides information for the Internet community. It does not specify an Internet standard.

This report attempts to summarize the key features of OSPF V2. It also attempts to analyze how the protocol will perform and scale in the Internet. This memo provides information for the Internet community. It does not specify any Internet standard.

This memo describes client requirements for real-time communication services. This memo provides information for the Internet community, and requests discussion and suggestions for improvements. It does not specify any standard.

This memo is intended to explore how Type-of-Service might be implemented in the Internet. The proposal describes a method of queuing which can provide the different classes of service. The technique also prohibits one class of service from consuming excessive resources or excluding other classes of service. This is an "idea paper" and discussion is strongly encouraged.