draft-ietf-rmcat-wireless-tests-11.txt		rfc8869.txt
	Network Working Group Z. Sarker		Internet Engineering Task Force (IETF) Z. Sarker
	Internet-Draft Ericsson AB		Request for Comments: 8869 Ericsson AB
	Intended status: Informational X. Zhu		Category: Informational X. Zhu
	Expires: September 14, 2020 J. Fu		ISSN: 2070-1721 J. Fu
	Cisco Systems		Cisco Systems
	March 13, 2020		January 2021
	Evaluation Test Cases for Interactive Real-Time Media over Wireless		Evaluation Test Cases for Interactive Real-Time Media over Wireless
	Networks		Networks
	draft-ietf-rmcat-wireless-tests-11
	Abstract		Abstract
	The Real-time Transport Protocol (RTP) is a common transport choice		The Real-time Transport Protocol (RTP) is a common transport choice
	for interactive multimedia communication applications. The		for interactive multimedia communication applications. The
	performance of these applications typically depends on a well-		performance of these applications typically depends on a well-
	functioning congestion control algorithm. To ensure a seamless and		functioning congestion control algorithm. To ensure a seamless and
	robust user experience, a well-designed RTP-based congestion control		robust user experience, a well-designed RTP-based congestion control
	algorithm should work well across all access network types. This		algorithm should work well across all access network types. This
	document describes test cases for evaluating performances of		document describes test cases for evaluating performances of
	candidate congestion control algorithms over cellular and Wi-Fi		candidate congestion control algorithms over cellular and Wi-Fi
	networks.		networks.
	Status of This Memo		Status of This Memo
	This Internet-Draft is submitted in full conformance with the		This document is not an Internet Standards Track specification; it is
	provisions of BCP 78 and BCP 79.		published for informational purposes.
	Internet-Drafts are working documents of the Internet Engineering
	Task Force (IETF). Note that other groups may also distribute
	working documents as Internet-Drafts. The list of current Internet-
	Drafts is at https://datatracker.ietf.org/drafts/current/.
	Internet-Drafts are draft documents valid for a maximum of six months		This document is a product of the Internet Engineering Task Force
	and may be updated, replaced, or obsoleted by other documents at any		(IETF). It represents the consensus of the IETF community. It has
	time. It is inappropriate to use Internet-Drafts as reference		received public review and has been approved for publication by the
	material or to cite them other than as "work in progress."		Internet Engineering Steering Group (IESG). Not all documents
			approved by the IESG are candidates for any level of Internet
			Standard; see Section 2 of RFC 7841.
	This Internet-Draft will expire on September 14, 2020.		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/rfc8869.
	Copyright Notice		Copyright Notice
	Copyright (c) 2020 IETF Trust and the persons identified as the		Copyright (c) 2021 IETF Trust and the persons identified as the
	document authors. All rights reserved.		document authors. All rights reserved.
	This document is subject to BCP 78 and the IETF Trust's Legal		This document is subject to BCP 78 and the IETF Trust's Legal
	Provisions Relating to IETF Documents		Provisions Relating to IETF Documents
	(https://trustee.ietf.org/license-info) in effect on the date of		(https://trustee.ietf.org/license-info) in effect on the date of
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	carefully, as they describe your rights and restrictions with respect		carefully, as they describe your rights and restrictions with respect
	to this document. Code Components extracted from this document must		to this document. Code Components extracted from this document must
	include Simplified BSD License text as described in Section 4.e of		include Simplified BSD License text as described in Section 4.e of
	the Trust Legal Provisions and are provided without warranty as		the Trust Legal Provisions and are provided without warranty as
	described in the Simplified BSD License.		described in the Simplified BSD License.
	Table of Contents		Table of Contents
	1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3		1. Introduction
	2. Cellular Network Specific Test Cases . . . . . . . . . . . . 3		2. Cellular Network Specific Test Cases
	2.1. Varying Network Load . . . . . . . . . . . . . . . . . . 6		2.1. Varying Network Load
	2.1.1. Network Connection . . . . . . . . . . . . . . . . . 6		2.1.1. Network Connection
	2.1.2. Simulation Setup . . . . . . . . . . . . . . . . . . 7		2.1.2. Simulation Setup
	2.1.3. Expected behavior . . . . . . . . . . . . . . . . . . 9		2.1.3. Expected Behavior
	2.2. Bad Radio Coverage . . . . . . . . . . . . . . . . . . . 9		2.2. Bad Radio Coverage
	2.2.1. Network connection . . . . . . . . . . . . . . . . . 9		2.2.1. Network Connection
	2.2.2. Simulation Setup . . . . . . . . . . . . . . . . . . 9		2.2.2. Simulation Setup
	2.2.3. Expected behavior . . . . . . . . . . . . . . . . . . 10		2.2.3. Expected Behavior
	2.3. Desired Evaluation Metrics for cellular test cases . . . 10		2.3. Desired Evaluation Metrics for Cellular Test Cases
	3. Wi-Fi Networks Specific Test Cases . . . . . . . . . . . . . 10		3. Wi-Fi Networks Specific Test Cases
	3.1. Bottleneck in Wired Network . . . . . . . . . . . . . . . 12		3.1. Bottleneck in Wired Network
	3.1.1. Network topology . . . . . . . . . . . . . . . . . . 12		3.1.1. Network Topology
	3.1.2. Test/simulation setup . . . . . . . . . . . . . . . . 13		3.1.2. Test/Simulation Setup
	3.1.3. Typical test scenarios . . . . . . . . . . . . . . . 14		3.1.3. Typical Test Scenarios
	3.1.4. Expected behavior . . . . . . . . . . . . . . . . . . 15		3.1.4. Expected Behavior
	3.2. Bottleneck in Wi-Fi Network . . . . . . . . . . . . . . . 15		3.2. Bottleneck in Wi-Fi Network
	3.2.1. Network topology . . . . . . . . . . . . . . . . . . 15		3.2.1. Network Topology
	3.2.2. Test/simulation setup . . . . . . . . . . . . . . . . 16		3.2.2. Test/Simulation Setup
	3.2.3. Typical test scenarios . . . . . . . . . . . . . . . 17		3.2.3. Typical Test Scenarios
	3.2.4. Expected behavior . . . . . . . . . . . . . . . . . . 18		3.2.4. Expected Behavior
	3.3. Other Potential Test Cases . . . . . . . . . . . . . . . 19		3.3. Other Potential Test Cases
	3.3.1. EDCA/WMM usage . . . . . . . . . . . . . . . . . . . 19		3.3.1. EDCA/WMM usage
	3.3.2. Effect of heterogeneous link rates . . . . . . . . . 19		3.3.2. Effect of Heterogeneous Link Rates
	4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 20		4. IANA Considerations
	5. Security Considerations . . . . . . . . . . . . . . . . . . . 20		5. Security Considerations
	6. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 20		6. References
	7. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 21		6.1. Normative References
	8. References . . . . . . . . . . . . . . . . . . . . . . . . . 21		6.2. Informative References
	8.1. Normative References . . . . . . . . . . . . . . . . . . 21		Contributors
	8.2. Informative References . . . . . . . . . . . . . . . . . 22		Acknowledgments
	Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 22		Authors' Addresses
	1. Introduction		1. Introduction
	Wireless networks (both cellular and Wi-Fi [IEEE802.11]) are an		Wireless networks (both cellular and Wi-Fi [IEEE802.11]) are an
	integral and increasingly more significant part of the Internet.		integral and increasingly more significant part of the Internet.
	Typical application scenarios for interactive multimedia		Typical application scenarios for interactive multimedia
	communication over wireless include from video conferencing calls in		communication over wireless include video conferencing calls in a bus
	a bus or train as well as live media streaming at home. It is well		or train as well as live media streaming at home. It is well known
	known that the characteristics and technical challenges for		that the characteristics and technical challenges for supporting
	supporting multimedia services over wireless are very different from		multimedia services over wireless are very different from those of
	those of providing the same service over a wired network. Although		providing the same service over a wired network. Although the basic
	the basic test cases as defined in [I-D.ietf-rmcat-eval-test] have		test cases as defined in [RFC8867] have covered many common effects
	covered many common effects of network impairments for evaluating		of network impairments for evaluating RTP-based congestion control
	RTP-based congestion control schemes, they remain to be tested over		schemes, they remain to be tested over characteristics and dynamics
	characteristics and dynamics unique to a given wireless environment.		unique to a given wireless environment. For example, in cellular
	For example, in cellular networks, the base station maintains		networks, the base station maintains individual queues per radio
	individual queues per radio bearer per user hence it leads to a		bearer per user hence it leads to a different nature of interactions
	different nature of interactions between traffic flows of different		between traffic flows of different users. This contrasts with a
	users. This contrasts with a typical wired network setting where		typical wired network setting where traffic flows from all users
	traffic flows from all users share the same queue at the bottleneck.		share the same queue at the bottleneck. Furthermore, user mobility
	Furthermore, user mobility patterns in a cellular network differ from		patterns in a cellular network differ from those in a Wi-Fi network.
	those in a Wi-Fi network. Therefore, it is important to evaluate the		Therefore, it is important to evaluate the performance of proposed
	performance of proposed candidate RTP-based congestion control		candidate RTP-based congestion control solutions over cellular mobile
	solutions over cellular mobile networks and over Wi-Fi networks		networks and over Wi-Fi networks respectively.
	respectively.
	The draft [I-D.ietf-rmcat-eval-criteria] provides the guideline for		[RFC8868] provides guidelines for evaluating candidate algorithms and
	evaluating candidate algorithms and recognizes the importance of		recognizes the importance of testing over wireless access networks.
	testing over wireless access networks. However, it does not describe		However, it does not describe any specific test cases for performance
	any specific test cases for performance evaluation of candidate		evaluation of candidate algorithms. This document describes test
	algorithms. This document describes test cases specifically		cases specifically targeting cellular and Wi-Fi networks.
	targeting cellular and Wi-Fi networks.
	2. Cellular Network Specific Test Cases		2. Cellular Network Specific Test Cases
	A cellular environment is more complicated than its wireline		A cellular environment is more complicated than its wireline
	counterpart since it seeks to provide services in the context of		counterpart since it seeks to provide services in the context of
	variable available bandwidth, location dependencies and user		variable available bandwidth, location dependencies, and user
	mobilities at different speeds. In a cellular network, the user may		mobilities at different speeds. In a cellular network, the user may
	reach the cell edge which may lead to a significant amount of		reach the cell edge, which may lead to a significant number of
	retransmissions to deliver the data from the base station to the		retransmissions to deliver the data from the base station to the
	destination and vice versa. These radio links will often act as a		destination and vice versa. These radio links will often act as a
	bottleneck for the rest of the network and will eventually lead to		bottleneck for the rest of the network and will eventually lead to
	excessive delays or packet drops. An efficient retransmission or		excessive delays or packet drops. An efficient retransmission or
	link adaptation mechanism can reduce the packet loss probability but		link adaptation mechanism can reduce the packet loss probability, but
	there will remain some packet losses and delay variations. Moreover,		some packet losses and delay variations will remain. Moreover, with
	with increased cell load or handover to a congested cell, congestion		increased cell load or handover to a congested cell, congestion in
	in the transport network will become even worse. Besides, there		the transport network will become even worse. Besides, there exist
	exist certain characteristics that distinguish the cellular network		certain characteristics that distinguish the cellular network from
	from other wireless access networks such as Wi-Fi. In a cellular		other wireless access networks such as Wi-Fi. In a cellular network:
	network --
	o The bottleneck is often a shared link with relatively few users.		* The bottleneck is often a shared link with relatively few users.
	* The cost per bit over the shared link varies over time and is		- The cost per bit over the shared link varies over time and is
	different for different users.		different for different users.
	* Leftover/unused resources can be consumed by other greedy		- Leftover/unused resources can be consumed by other greedy
	users.		users.
	o Queues are always per radio bearer hence each user can have many		* Queues are always per radio bearer, hence each user can have many
	such queues.		such queues.
	o Users can experience both Inter and Intra Radio Access Technology		* Users can experience both inter- and intra-Radio Access Technology
	(RAT) handovers (see [HO-def-3GPP] for the definition of		(RAT) handovers (see [HO-def-3GPP] for the definition of
	"handover").		"handover").
	o Handover between cells or change of serving cells (as described in		* Handover between cells or change of serving cells (as described in
	[HO-LTE-3GPP] and [HO-UMTS-3GPP]) might cause user plane		[HO-LTE-3GPP] and [HO-UMTS-3GPP]) might cause user plane
	interruptions which can lead to bursts of packet losses, delay		interruptions, which can lead to bursts of packet losses, delay,
	and/or jitter. The exact behavior depends on the type of radio		and/or jitter. The exact behavior depends on the type of radio
	bearer. Typically, the default best-effort bearers do not		bearer. Typically, the default best-effort bearers do not
	generate packet loss, instead, packets are queued up and		generate packet loss, instead, packets are queued up and
	transmitted once the handover is completed.		transmitted once the handover is completed.
	o The network part decides how much the user can transmit.		* The network part decides how much the user can transmit.
	o The cellular network has variable link capacity per user.		* The cellular network has variable link capacity per user.
	* It can vary as fast as a period of milliseconds.		- It can vary as fast as a period of milliseconds.
	* It depends on many factors (such as distance, speed,		- It depends on many factors (such as distance, speed,
	interference, different flows).		interference, different flows).
	* It uses complex and smart link adaptation which makes the link		- It uses complex and smart link adaptation, which makes the link
	behavior ever more dynamic.		behavior ever more dynamic.
	* The scheduling priority depends on the estimated throughput.		- The scheduling priority depends on the estimated throughput.
	o Both Quality of Service (QoS) and non-QoS radio bearers can be		* Both Quality of Service (QoS) and non-QoS radio bearers can be
	used.		used.
	Hence, a real-time communication application operating over a		Hence, a real-time communication application operating over a
	cellular network needs to cope with a shared bottleneck link and		cellular network needs to cope with a shared bottleneck link and
	variable link capacity, events like handover, non-congestion related		variable link capacity, events like handover, non-congestion-related
	loss, abrupt changes in bandwidth (both short term and long term) due		loss, and abrupt changes in bandwidth (both short term and long term)
	to handover, network load and bad radio coverage. Even though 3GPP		due to handover, network load, and bad radio coverage. Even though
	has defined QoS bearers [QoS-3GPP] to ensure high-quality user		3GPP has defined QoS bearers [QoS-3GPP] to ensure high-quality user
	experience, it is still preferable for real-time applications to		experience, it is still preferable for real-time applications to
	behave in an adaptive manner.		behave in an adaptive manner.
	Different mobile operators deploy their own cellular networks with		Different mobile operators deploy their own cellular networks with
	their own set of network functionalities and policies. Usually, a		their own set of network functionalities and policies. Usually, a
	mobile operator network includes a range of radio access technologies		mobile operator network includes a range of radio access technologies
	such as 3G and 4G/LTE. Looking at the specifications of such radio		such as 3G and 4G/LTE. Looking at the specifications of such radio
	technologies it is evident that only the more recent radio		technologies, it is evident that only the more recent radio
	technologies can support the high bandwidth requirements from real-		technologies can support the high bandwidth requirements from real-
	time interactive video applications. The future real-time		time interactive video applications. Future real-time interactive
	interactive application will impose even greater demand on cellular		applications will impose even greater demand on cellular network
	network performance which makes 4G (and beyond) radio technologies		performance, which makes 4G (and beyond) radio technologies more
	more suitable for such genre of application.		suitable for such genre of application.
	The key factors in defining test cases for cellular networks are:		The key factors in defining test cases for cellular networks are:
	o Shared and varying link capacity		* Shared and varying link capacity
	o Mobility		* Mobility
	o Handover		* Handover
	However, these factors are typically highly correlated in a cellular		However, these factors are typically highly correlated in a cellular
	network. Therefore, instead of devising separate test cases for		network. Therefore, instead of devising separate test cases for
	individual important events, we have divided the test case into two		individual important events, we have divided the test cases into two
	categories. It should be noted that the goal of the following test		categories. It should be noted that the goal of the following test
	cases is to evaluate the performance of candidate algorithms over the		cases is to evaluate the performance of candidate algorithms over the
	radio interface of the cellular network. Hence it is assumed that		radio interface of the cellular network. Hence, it is assumed that
	the radio interface is the bottleneck link between the communicating		the radio interface is the bottleneck link between the communicating
	peers and that the core network does not introduce any extra		peers and that the core network does not introduce any extra
	congestion along the path. Consequently, this draft has kept as out		congestion along the path. Consequently, this document has left out
	of scope the combination of multiple access technologies involving		of scope the combination of multiple access technologies involving
	both cellular and Wi-Fi users. In this latter case the shared		both cellular and Wi-Fi users. In this latter case, the shared
	bottleneck is likely at the wired backhaul link. These test cases		bottleneck is likely at the wired backhaul link. These test cases
	further assume a typical real-time telephony scenario where one real-		further assume a typical real-time telephony scenario where one real-
	time session consists of one voice stream and one video stream.		time session consists of one voice stream and one video stream.
	Even though it is possible to carry out tests over operational		Even though it is possible to carry out tests over operational
	cellular networks (e.g., LTE/5G), and actually such tests are already		cellular networks (e.g., LTE/5G), and actually such tests are already
	available today, these tests cannot in general be carried out in a		available today, these tests cannot in general be carried out in a
	deterministic fashion to ensure repeatability. The main reason is		deterministic fashion to ensure repeatability. The main reason is
	that these networks are controlled by cellular operators and there		that these networks are controlled by cellular operators, and there
	exist various amounts of competing traffic in the same cell(s). In		exists various amounts of competing traffic in the same cell(s). In
	practice, it is only in underground mines that one can carry out near		practice, it is only in underground mines that one can carry out near
	deterministic testing. Even there, it is not guaranteed either as		deterministic testing. Even there, it is not guaranteed either as
	workers in the mines may carry with them their personal mobile		workers in the mines may carry with them their personal mobile
	phones. Furthermore, the underground mining setting may not reflect		phones. Furthermore, the underground mining setting may not reflect
	typical usage patterns in an urban setting. We, therefore, recommend		typical usage patterns in an urban setting. We, therefore, recommend
	that a cellular network simulator is used for the test cases defined		that a cellular network simulator be used for the test cases defined
	in this document, for example -- the LTE simulator in [NS-3].		in this document, for example -- the LTE simulator in [NS-3].
	2.1. Varying Network Load		2.1. Varying Network Load
	The goal of this test is to evaluate the performance of the candidate		The goal of this test is to evaluate the performance of the candidate
	congestion control algorithm under varying network load. The network		congestion control algorithm under varying network load. The network
	load variation is created by adding and removing network users a.k.a.		load variation is created by adding and removing network users,
	User Equipments (UEs) during the simulation. In this test case, each		a.k.a. User Equipment (UE), during the simulation. In this test
	user/UE in the media session is an endpoint following RTP-based		case, each user/UE in the media session is an endpoint following RTP-
	congestion control. User arrivals follow a Poisson distribution		based congestion control. User arrivals follow a Poisson
	proportional to the length of the call, to keep the number of users		distribution proportional to the length of the call, to keep the
	per cell fairly constant during the evaluation period. At the		number of users per cell fairly constant during the evaluation
	beginning of the simulation, there should be enough time to warm-up		period. At the beginning of the simulation, there should be enough
	the network. This is to avoid running the evaluation in an empty		time to warm up the network. This is to avoid running the evaluation
	network where network nodes are having empty buffers, low		in an empty network where network nodes have empty buffers and low
	interference at the beginning of the simulation. This network		interference at the beginning of the simulation. This network
	initialization period should be excluded from the evaluation period.		initialization period should be excluded from the evaluation period.
	Typically, the evaluation period starts 30 seconds after test		Typically, the evaluation period starts 30 seconds after test
	initialization.		initialization.
	This test case also includes user mobility and some competing		This test case also includes user mobility and some competing
	traffic. The latter includes both the same types of flows (with same		traffic. The latter includes both the same types of flows (with same
	adaptation algorithms) and different types of flows (with different		adaptation algorithms) and different types of flows (with different
	services and congestion control schemes).		services and congestion control schemes).
	2.1.1. Network Connection		2.1.1. Network Connection
	Each mobile user is connected to a fixed user. The connection		Each mobile user is connected to a fixed user. The connection
	between the mobile user and fixed user consists of a cellular radio		between the mobile user and fixed user consists of a cellular radio
	access, an Evolved Packet Core (EPC) and an Internet connection. The		access, an Evolved Packet Core (EPC), and an Internet connection.
	mobile user is connected to the EPC using cellular radio access		The mobile user is connected to the EPC using cellular radio access
	technology which is further connected to the Internet. At the other		technology, which is further connected to the Internet. At the other
	end, the fixed user is connected to the Internet via wired connection		end, the fixed user is connected to the Internet via a wired
	with sufficiently high bandwidth, for instance, 10 Gbps, so that the		connection with sufficiently high bandwidth, for instance, 10 Gbps,
	system bottleneck is on the cellular radio access interface. The		so that the system bottleneck is on the cellular radio access
	wired connection to in this setup does not introduce any network		interface. The wired connection in this setup does not introduce any
	impairments to the test; it only adds 10 ms of one-way propagation		network impairments to the test; it only adds 10 ms of one-way
	delay.		propagation delay.
	The path from the fixed user to the mobile users is defined as		The path from the fixed user to the mobile users is defined as
	"Downlink" and the path from the mobile users to the fixed user is		"downlink", and the path from the mobile users to the fixed user is
	defined as "Uplink". We assume that only uplink or downlink is		defined as "uplink". We assume that only uplink or downlink is
	congested for mobile users. Hence, we recommend that the uplink and		congested for mobile users. Hence, we recommend that the uplink and
	downlink simulations are run separately.		downlink simulations are run separately.
	uplink		uplink
	++))) +-------------------------->		++))) +-------------------------->
	++-+ ((o))		++-+ ((o))
	| | / \ +-------+ +------+ +---+		| | / \ +-------+ +------+ +---+
	+--+ / \----+ +-----+ +----+ |		+--+ / \----+ +-----+ +----+ |
	/ \ +-------+ +------+ +---+		/ \ +-------+ +------+ +---+
	UE BS EPC Internet fixed		UE BS EPC Internet fixed
	<--------------------------+		<--------------------------+
	downlink		downlink
	Figure 1: Simulation Topology		Figure 1: Simulation Topology
	2.1.2. Simulation Setup		2.1.2. Simulation Setup
	The values enclosed within "[ ]" for the following simulation		The values enclosed within "[ ]" for the following simulation
	attributes follow the same notion as in [I-D.ietf-rmcat-eval-test].		attributes follow the same notion as in [RFC8867]. The desired
	The desired simulation setup is as follows --		simulation setup is as follows:
	1. Radio environment:		Radio environment:
	A. Deployment and propagation model: 3GPP case 1 (see		Deployment and propagation model: 3GPP case 1 (see
	[HO-deploy-3GPP])		[HO-deploy-3GPP])
	B. Antenna: Multiple-Input and Multiple-Output (MIMO), 2D or 3D		Antenna: Multiple-Input and Multiple-Output (MIMO), 2D or 3D
	antenna pattern.		antenna pattern
	C. Mobility: [3km/h, 30km/h]		Mobility: [3 km/h, 30 km/h]
	D. Transmission bandwidth: 10MHz		Transmission bandwidth: 10 MHz
	E. Number of cells: multi-cell deployment (3 Cells per Base		Number of cells: multi-cell deployment (3 cells per Base Station
	Station (BS) * 7 BS) = 21 cells		(BS) * 7 BS) = 21 cells
	F. Cell radius: 166.666 Meters		Cell radius: 166.666 meters
	G. Scheduler: Proportional fair with no priority		Scheduler: Proportional fair with no priority
	H. Bearer: Default bearer for all traffic.		Bearer: Default bearer for all traffic
	I. Active Queue Management (AQM) settings: AQM [on,off]		Active Queue Management (AQM) settings: AQM [on, off]
	2. End-to-end Round Trip Time (RTT): [40ms, 150ms]		End-to-end Round Trip Time (RTT): [40 ms, 150 ms]
	3. User arrival model: Poisson arrival model		User arrival model: Poisson arrival model
	4. User intensity:		User intensity:
	* Downlink user intensity: {0.7, 1.4, 2.1, 2.8, 3.5, 4.2, 4.9,		Downlink user intensity: {0.7, 1.4, 2.1, 2.8, 3.5, 4.2, 4.9, 5.6,
	5.6, 6.3, 7.0, 7.7, 8.4, 9,1, 9.8, 10.5}		6.3, 7.0, 7.7, 8.4, 9,1, 9.8, 10.5}
	* Uplink user intensity : {0.7, 1.4, 2.1, 2.8, 3.5, 4.2, 4.9,		Uplink user intensity: {0.7, 1.4, 2.1, 2.8, 3.5, 4.2, 4.9, 5.6,
	5.6, 6.3, 7.0}		6.3, 7.0}
	5. Simulation duration: 91s		Simulation duration: 91 s
	6. Evaluation period: 30s-60s		Evaluation period: 30 s - 60 s
	7. Media traffic:		Media traffic:
	1. Media type: Video		Media type: Video
	a. Media direction: [Uplink, Downlink]		Media direction: [uplink, downlink]
	b. Number of Media source per user: One (1)		Number of media sources per user: One (1)
	c. Media duration per user: 30s		Media duration per user: 30 s
	d. Media source: same as defined in Section 4.3 of		Media source: same as defined in Section 4.3 of [RFC8867]
	[I-D.ietf-rmcat-eval-test]
	2. Media Type: Audio		Media type: Audio
	a. Media direction: Uplink and Downlink		Media direction: [uplink, downlink]
	b. Number of Media source per user: One (1)		Number of media sources per user: One (1)
	c. Media duration per user: 30s		Media duration per user: 30 s
	d. Media codec: Constant Bit Rate (CBR)		Media codec: Constant Bit Rate (CBR)
	e. Media bitrate: 20 Kbps		Media bitrate: 20 Kbps
	f. Adaptation: off		Adaptation: off
	8. Other traffic models:		Other traffic models:
	* Downlink simulation: Maximum of 4Mbps/cell (web browsing or		Downlink simulation: Maximum of 4 Mbps/cell (web browsing or FTP
	FTP traffic following default TCP congestion control		traffic following default TCP congestion control [RFC5681])
	[RFC5681])
	* Unlink simulation: Maximum of 2Mbps/cell (web browsing or FTP		Uplink simulation: Maximum of 2 Mbps/cell (web browsing or FTP
	traffic following default TCP congestion control [RFC5681])		traffic following default TCP congestion control [RFC5681])
	2.1.3. Expected behavior		2.1.3. Expected Behavior
	The investigated congestion control algorithms should result in		The investigated congestion control algorithms should result in
	maximum possible network utilization and stability in terms of rate		maximum possible network utilization and stability in terms of rate
	variations, lowest possible end to end frame latency, network latency		variations, lowest possible end-to-end frame latency, network
	and Packet Loss Rate (PLR) at different cell load levels.		latency, and Packet Loss Rate (PLR) at different cell load levels.
	2.2. Bad Radio Coverage		2.2. Bad Radio Coverage
	The goal of this test is to evaluate the performance of candidate		The goal of this test is to evaluate the performance of the candidate
	congestion control algorithm when users visit part of the network		congestion control algorithm when users visit part of the network
	with bad radio coverage. The scenario is created by using a larger		with bad radio coverage. The scenario is created by using a larger
	cell radius than that in the previous test case. In this test case,		cell radius than that in the previous test case. In this test case,
	each user/UE in the media session is an endpoint following RTP-based		each user/UE in the media session is an endpoint following RTP-based
	congestion control. User arrivals follow a Poisson distribution		congestion control. User arrivals follow a Poisson distribution
	proportional to the length of the call, to keep the number of users		proportional to the length of the call, to keep the number of users
	per cell fairly constant during the evaluation period. At the		per cell fairly constant during the evaluation period. At the
	beginning of the simulation, there should be enough amount of time to		beginning of the simulation, there should be enough time to warm up
	warm-up the network. This is to avoid running the evaluation in an		the network. This is to avoid running the evaluation in an empty
	empty network where network nodes are having empty buffers, low		network where network nodes have empty buffers and low interference
	interference at the beginning of the simulation. This network		at the beginning of the simulation. This network initialization
	initialization period should be excluded from the evaluation period.		period should be excluded from the evaluation period. Typically, the
	Typically, the evaluation period starts 30 seconds after test		evaluation period starts 30 seconds after test initialization.
	initialization.
	This test case also includes user mobility and some competing		This test case also includes user mobility and some competing
	traffic. The latter includes the same kind of flows (with same		traffic. The latter includes the same kind of flows (with same
	adaptation algorithms).		adaptation algorithms).
	2.2.1. Network connection		2.2.1. Network Connection
	Same as defined in Section 2.1.1		Same as defined in Section 2.1.1.
	2.2.2. Simulation Setup		2.2.2. Simulation Setup
	The desired simulation setup is the same as the Varying Network Load		The desired simulation setup is the same as the Varying Network Load
	test case defined in Section 2.1 except the following changes:		test case defined in Section 2.1 except for the following changes:
	1. Radio environment: Same as defined in Section 2.1.2 except the		Radio environment: Same as defined in Section 2.1.2 except for the
	following:		following:
	A. Deployment and propagation model: 3GPP case 3 (see		Deployment and propagation model: 3GPP case 3 (see
	[HO-deploy-3GPP])		[HO-deploy-3GPP])
	B. Cell radius: 577.3333 Meters		Cell radius: 577.3333 meters
	C. Mobility: 3km/h		Mobility: 3 km/h
	2. User intensity = {0.7, 1.4, 2.1, 2.8, 3.5, 4.2, 4.9, 5.6, 6.3,		User intensity: {0.7, 1.4, 2.1, 2.8, 3.5, 4.2, 4.9, 5.6, 6.3, 7.0}
	7.0}
	3. Media traffic model: Same as defined in Section 2.1.2		Media traffic model: Same as defined in Section 2.1.2
	4. Other traffic models:		Other traffic models:
	* Downlink simulation: Maximum of 2Mbps/cell (web browsing or		Downlink simulation: Maximum of 2 Mbps/cell (web browsing or FTP
	FTP traffic following default TCP congestion control		traffic following default TCP congestion control [RFC5681])
	[RFC5681])
	* Unlink simulation: Maximum of 1Mbps/cell (web browsing or FTP		Uplink simulation: Maximum of 1 Mbps/cell (web browsing or FTP
	traffic following default TCP congestion control [RFC5681])		traffic following default TCP congestion control [RFC5681])
	2.2.3. Expected behavior		2.2.3. Expected Behavior
	The investigated congestion control algorithms should result in		The investigated congestion control algorithms should result in
	maximum possible network utilization and stability in terms of rate		maximum possible network utilization and stability in terms of rate
	variations, lowest possible end to end frame latency, network latency		variations, lowest possible end-to-end frame latency, network
	and Packet Loss Rate (PLR) at different cell load levels.		latency, and Packet Loss Rate (PLR) at different cell load levels.
	2.3. Desired Evaluation Metrics for cellular test cases		2.3. Desired Evaluation Metrics for Cellular Test Cases
	The evaluation criteria document [I-D.ietf-rmcat-eval-criteria]		The evaluation criteria document [RFC8868] defines the metrics to be
	defines the metrics to be used to evaluate candidate algorithms.		used to evaluate candidate algorithms. Considering the nature and
	Considering the nature and distinction of cellular networks we		distinction of cellular networks, we recommend that at least the
	recommend that at least the following metrics be used to evaluate the		following metrics be used to evaluate the performance of the
	performance of the candidate algorithms:		candidate algorithms:
	o Average cell throughput (for all cells), shows cell utilizations.		* Average cell throughput (for all cells), shows cell utilization.
	o Application sending and receiving bitrate, goodput.		* Application sending and receiving bitrate, goodput.
	o Packet Loss Rate (PLR).		* Packet Loss Rate (PLR).
	o End-to-end Media frame delay. For video, this means the delay		* End-to-end media frame delay. For video, this means the delay
	from capture to display.		from capture to display.
	o Transport delay.		* Transport delay.
	o Algorithm stability in terms of rate variation.		* Algorithm stability in terms of rate variation.
	3. Wi-Fi Networks Specific Test Cases		3. Wi-Fi Networks Specific Test Cases
	Given the prevalence of Internet access links over Wi-Fi, it is		Given the prevalence of Internet access links over Wi-Fi, it is
	important to evaluate candidate RTP-based congestion control		important to evaluate candidate RTP-based congestion control
	solutions over test cases that include Wi-Fi access links. Such		solutions over test cases that include Wi-Fi access links. Such
	evaluations should highlight the inherently different characteristics		evaluations should highlight the inherently different characteristics
	of Wi-Fi networks in contrast to their wired counterparts:		of Wi-Fi networks in contrast to their wired counterparts:
	o The wireless radio channel is subject to interference from nearby		* The wireless radio channel is subject to interference from nearby
	transmitters, multipath fading, and shadowing. These effects lead		transmitters, multipath fading, and shadowing. These effects lead
	to fluctuations in the link throughput and sometimes an error-		to fluctuations in the link throughput and sometimes an error-
	prone communication environment.		prone communication environment.
	o Available network bandwidth is not only shared over the air		* Available network bandwidth is not only shared over the air
	between concurrent users but also between uplink and downlink		between concurrent users but also between uplink and downlink
	traffic due to the half-duplex nature of the wireless transmission		traffic due to the half-duplex nature of the wireless transmission
	medium.		medium.
	o Packet transmissions over Wi-Fi are susceptible to contentions and		* Packet transmissions over Wi-Fi are susceptible to contentions and
	collisions over the air. Consequently, traffic load beyond a		collisions over the air. Consequently, traffic load beyond a
	certain utilization level over a Wi-Fi network can introduce		certain utilization level over a Wi-Fi network can introduce
	frequent collisions over the air and significant network overhead,		frequent collisions over the air and significant network overhead,
	as well as packet drops due to buffer overflow at the		as well as packet drops due to buffer overflow at the
	transmitters. This, in turn, leads to excessive delay,		transmitters. This, in turn, leads to excessive delay,
	retransmissions, packet losses and lower effective bandwidth for		retransmissions, packet losses, and lower effective bandwidth for
	applications. Note further that the collision-induced delay and		applications. Note further that the collision-induced delay and
	loss patterns are qualitatively different from those caused by		loss patterns are qualitatively different from those caused by
	congestion over a wired connection.		congestion over a wired connection.
	o The IEEE 802.11 standard (i.e., Wi-Fi) supports multi-rate		* The IEEE 802.11 standard (i.e., Wi-Fi) supports multi-rate
	transmission capabilities by dynamically choosing the most		transmission capabilities by dynamically choosing the most
	appropriate modulation and coding scheme (MCS) for the given		appropriate modulation and coding scheme (MCS) for the given
	received signal strength. A different choice in the MCS Index		received signal strength. A different choice in the MCS Index
	leads to different physical-layer (PHY-layer) link rates and		leads to different physical-layer (PHY-layer) link rates and
	consequently different application-layer throughput.		consequently different application-layer throughput.
	o The presence of legacy devices (e.g., ones operating only in IEEE		* The presence of legacy devices (e.g., ones operating only in IEEE
	802.11b) at a much lower PHY-layer link rate can significantly		802.11b) at a much lower PHY-layer link rate can significantly
	slow down the rest of a modern Wi-Fi network. As discussed in		slow down the rest of a modern Wi-Fi network. As discussed in
	[Heusse2003], the main reason for such anomaly is that it takes		[Heusse2003], the main reason for such anomaly is that it takes
	much longer to transmit the same packet over a slower link than		much longer to transmit the same packet over a slower link than
	over a faster link, thereby consuming a substantial portion of air		over a faster link, thereby consuming a substantial portion of air
	time.		time.
	o Handover from one Wi-Fi Access Point (AP) to another may lead to		* Handover from one Wi-Fi Access Point (AP) to another may lead to
	excessive packet delays and losses during the process.		excessive packet delays and losses during the process.
	o IEEE 802.11e has introduced the Enhanced Distributed Channel		* IEEE 802.11e has introduced the Enhanced Distributed Channel
	Access (EDCA) mechanism to allow different traffic categories to		Access (EDCA) mechanism to allow different traffic categories to
	contend for channel access using different random back-off		contend for channel access using different random back-off
	parameters. This mechanism is a mandatory requirement for the Wi-		parameters. This mechanism is a mandatory requirement for the Wi-
	Fi Multimedia (WMM) certification in Wi-Fi Alliance. It allows		Fi Multimedia (WMM) certification in Wi-Fi Alliance. It allows
	for prioritization of real-time application traffic such as voice		for prioritization of real-time application traffic such as voice
	and video over non-urgent data transmissions (e.g., file		and video over non-urgent data transmissions (e.g., file
	transfer).		transfer).
	In summary, the presence of Wi-Fi access links in different network		In summary, the presence of Wi-Fi access links in different network
	topologies can exert different impact on the network performance in		topologies can exert different impacts on the network performance in
	terms of application-layer effective throughput, packet loss rate,		terms of application-layer effective throughput, packet loss rate,
	and packet delivery delay. These, in turn, will influence the		and packet delivery delay. These, in turn, will influence the
	behavior of end-to-end real-time multimedia congestion control.		behavior of end-to-end real-time multimedia congestion control.
	Unless otherwise mentioned, the test cases in this section choose the		Unless otherwise mentioned, the test cases in this section choose the
	PHY- and MAC-layer parameters based on the IEEE 802.11n Standard.		PHY- and MAC-layer parameters based on the IEEE 802.11n standard.
	Statistics collected from enterprise Wi-Fi networks show that the two		Statistics collected from enterprise Wi-Fi networks show that the two
	dominant physical modes are 802.11n and 802.11ac, accounting for 41%		dominant physical modes are 802.11n and 802.11ac, accounting for 41%
	and 58% of connected devices. As Wi-Fi standards evolve over time --		and 58% of connected devices, respectively. As Wi-Fi standards
	for instance, with the introduction of the emerging Wi-Fi 6 (based on		evolve over time -- for instance, with the introduction of the
	IEEE 802.11ax) products -- the PHY- and MAC-layer test case		emerging Wi-Fi 6 (based on IEEE 802.11ax) products -- the PHY- and
	specifications need to be updated accordingly to reflect such		MAC-layer test case specifications need to be updated accordingly to
	changes.		reflect such changes.
	Typically, a Wi-Fi access network connects to a wired infrastructure.		Typically, a Wi-Fi access network connects to a wired infrastructure.
	Either the wired or the Wi-Fi segment of the network can be the		Either the wired or the Wi-Fi segment of the network can be the
	bottleneck. The following sections describe basic test cases for		bottleneck. The following sections describe basic test cases for
	both scenarios separately. The same set of performance metrics as in		both scenarios separately. The same set of performance metrics as in
	[I-D.ietf-rmcat-eval-test]) should be collected for each test case.		[RFC8867]) should be collected for each test case.
	We recommend to carry out the test cases as defined in this document		We recommend carrying out the test cases as defined in this document
	using a simulator, such as [NS-2] or [NS-3]. When feasible, it is		using a simulator, such as [NS-2] or [NS-3]. When feasible, it is
	encouraged to perform testbed-based evaluations using Wi-Fi access		encouraged to perform testbed-based evaluations using Wi-Fi access
	points and endpoints running up-to-date IEEE 802.11 protocols, such		points and endpoints running up-to-date IEEE 802.11 protocols, such
	as 802.11ac and the emerging Wi-Fi 6, so as to verify the viability		as 802.11ac and the emerging Wi-Fi 6, so as to verify the viability
	of the candidate schemes.		of the candidate schemes.
	3.1. Bottleneck in Wired Network		3.1. Bottleneck in Wired Network
	The test scenarios below are intended to mimic the setup of video		The test scenarios below are intended to mimic the setup of video
	conferencing over Wi-Fi connections from the home. Typically, the		conferencing over Wi-Fi connections from the home. Typically, the
	Wi-Fi home network is not congested and the bottleneck is present		Wi-Fi home network is not congested, and the bottleneck is present
	over the wired home access link. Although it is expected that test		over the wired home access link. Although it is expected that test
	evaluation results from this section are similar to those as in		evaluation results from this section are similar to those in
	[I-D.ietf-rmcat-eval-test], it is still worthwhile to run through		[RFC8867], it is still worthwhile to run through these tests as
	these tests as sanity checks.		sanity checks.
	3.1.1. Network topology		3.1.1. Network Topology
	Figure 2 shows the network topology of Wi-Fi test cases. The test		Figure 2 shows the network topology of Wi-Fi test cases. The test
	contains multiple mobile nodes (MNs) connected to a common Wi-Fi		contains multiple mobile nodes (MNs) connected to a common Wi-Fi AP
	access point (AP) and their corresponding wired clients on fixed		and their corresponding wired clients on fixed nodes (FNs). Each
	nodes (FNs). Each connection carries either a RTP-based media flow		connection carries either an RTP-based media flow or a TCP traffic
	or a TCP traffic flow. Directions of the flows can be uplink (i.e.,		flow. Directions of the flows can be uplink (i.e., from mobile nodes
	from mobile nodes to fixed nodes), downlink (i.e., from fixed nodes		to fixed nodes), downlink (i.e., from fixed nodes to mobile nodes),
	to mobile nodes), or bi-directional. The total number of		or bidirectional. The total number of uplink/downlink/bidirectional
	uplink/downlink/bi-directional flows for RTP-based media traffic and		flows for RTP-based media traffic and TCP traffic are denoted as N
	TCP traffic are denoted as N and M, respectively.		and M, respectively.
	Uplink		Uplink
	+----------------->+		+----------------->+
	+------+ +------+		+------+ +------+
	| MN_1 |)))) /=====| FN_1 |		| MN_1 |)))) /=====| FN_1 |
	+------+ )) // +------+		+------+ )) // +------+
	. )) // .		. )) // .
	. )) // .		. )) // .
	. )) // .		. )) // .
	+------+ +----+ +-----+ +------+		+------+ +----+ +-----+ +------+
	skipping to change at page 13, line 34 ¶		skipping to change at line 588 ¶
	+----------+ +----+ +-----+ +----------+		+----------+ +----+ +-----+ +----------+
	. )) \\ .		. )) \\ .
	. )) \\ .		. )) \\ .
	. )) \\ .		. )) \\ .
	+----------+ )) \\ +----------+		+----------+ )) \\ +----------+
	| MN_tcp_M |))) \=====| FN_tcp_M |		| MN_tcp_M |))) \=====| FN_tcp_M |
	+----------+ +----------+		+----------+ +----------+
	+<-----------------+		+<-----------------+
	Downlink		Downlink
	Figure 2: Network topology for Wi-Fi test cases		Figure 2: Network Topology for Wi-Fi Test Cases
	3.1.2. Test/simulation setup		3.1.2. Test/Simulation Setup
	o Test duration: 120s		Test duration: 120 s
	o Wi-Fi network characteristics:		Wi-Fi network characteristics:
	* Radio propagation model: Log-distance path loss propagation		Radio propagation model: Log-distance path loss propagation model
	model (see [NS3WiFi])		(see [NS3WiFi])
	* PHY- and MAC-layer configuration: IEEE 802.11n		PHY- and MAC-layer configuration: IEEE 802.11n
	* MCS Index at 11: 16-QAM 1/2, Raw Data Rate at 52Mbps		MCS Index at 11: Raw data rate at 52 Mbps, 16-QAM (Quadrature
			amplitude modulation) and 1/2 coding rate
	o Wired path characteristics:		Wired path characteristics:
	* Path capacity: 1Mbps		Path capacity: 1 Mbps
	* One-Way propagation delay: 50ms.		One-way propagation delay: 50 ms
	* Maximum end-to-end jitter: 30ms		Maximum end-to-end jitter: 30 ms
	* Bottleneck queue type: Drop tail.		Bottleneck queue type: Drop tail
	* Bottleneck queue size: 300ms.		Bottleneck queue size: 300 ms
	* Path loss ratio: 0%.		Path loss ratio: 0%
	o Application characteristics:		Application characteristics:
	* Media Traffic:		Media traffic:
	+ Media type: Video		Media type: Video
	+ Media direction: See Section 3.1.3		Media direction: See Section 3.1.3
	+ Number of media sources (N): See Section 3.1.3		Number of media sources (N): See Section 3.1.3
	+ Media timeline:		Media timeline:
	- Start time: 0s.		Start time: 0 s
	- End time: 119s.		End time: 119 s
	* Competing traffic:		Competing traffic:
	+ Type of sources: long-lived TCP or CBR over UDP		Type of sources: Long-lived TCP or CBR over UDP
	+ Traffic direction: See Section 3.1.3		Traffic direction: See Section 3.1.3
	+ Number of sources (M): See Section 3.1.3		Number of sources (M): See Section 3.1.3
	+ Congestion control: Default TCP congestion control [RFC5681]		Congestion control: Default TCP congestion control [RFC5681]
	or constant-bit-rate (CBR) traffic over UDP.		or CBR traffic over UDP
	+ Traffic timeline: See Section 3.1.3		Traffic timeline: See Section 3.1.3
	3.1.3. Typical test scenarios		3.1.3. Typical Test Scenarios
	o Single uplink RTP-based media flow: N=1 with uplink direction and		Single uplink RTP-based media flow: N=1 with uplink direction and
	M=0.		M=0.
	o One pair of bi-directional RTP-based media flows: N=2 (i.e., one		One pair of bidirectional RTP-based media flows: N=2 (i.e., one
	uplink flow and one downlink flow); M=0.		uplink flow and one downlink flow); M=0.
	o One pair of bi-directional RTP-based media flows: N=2; one uplink		One pair of bidirectional RTP-based media flows: N=2; one uplink on-
	on-off CBR flow over UDP: M=1 (uplink). The CBR flow has ON time		off CBR flow over UDP: M=1 (uplink). The CBR flow has ON time at
	at t=0s-60s and OFF time at t=60s-119s.		t=0s-60s and OFF time at t=60s-119s.
	o One pair of bi-directional RTP-based media flows: N=2; one uplink		One pair of bidirectional RTP-based media flows: N=2; one uplink
	off-on CBR flow over UDP: M=1 (uplink). The CBR flow has OFF time		off-on CBR flow over UDP: M=1 (uplink). The CBR flow has OFF time
	at t=0s-60s and ON time at t=60s-119s.		at t=0s-60s and ON time at t=60s-119s.
	o One RTP-based media flow competing against one long-live TCP flow		One RTP-based media flow competing against one long-lived TCP flow
	in the uplink direction: N=1 (uplink) and M = 1(uplink). The TCP		in the uplink direction: N=1 (uplink) and M=1 (uplink). The TCP
	flow has start time at t=0s and end time at t=119s.		flow has start time at t=0s and end time at t=119s.
	3.1.4. Expected behavior		3.1.4. Expected Behavior
	o Single uplink RTP-based media flow: the candidate algorithm is		Single uplink RTP-based media flow: The candidate algorithm is
	expected to detect the path capacity constraint, to converge to		expected to detect the path capacity constraint, to converge to
	the bottleneck link capacity, and to adapt the flow to avoid		the bottleneck link capacity, and to adapt the flow to avoid
	unwanted oscillations when the sending bit rate is approaching the		unwanted oscillations when the sending bit rate is approaching the
	bottleneck link capacity. No excessive oscillations in the media		bottleneck link capacity. No excessive oscillations in the media
	rate should be present.		rate should be present.
	o Bi-directional RTP-based media flows: the candidate algorithm is		Bidirectional RTP-based media flows: The candidate algorithm is
	expected to converge to the bottleneck capacity of the wired path		expected to converge to the bottleneck capacity of the wired path
	in both directions despite the presence of measurement noise over		in both directions despite the presence of measurement noise over
	the Wi-Fi connection. In the presence of background TCP or CBR		the Wi-Fi connection. In the presence of background TCP or CBR
	over UDP traffic, the rate of RTP-based media flows should adapt		over UDP traffic, the rate of RTP-based media flows should adapt
	promptly to the arrival and departure of background traffic flows.		promptly to the arrival and departure of background traffic flows.
	o One RTP-based media flow competing with long-live TCP flow in the		One RTP-based media flow competing with long-lived TCP flow in the
	uplink direction: the candidate algorithm is expected to avoid		uplink direction: The candidate algorithm is expected to avoid
	congestion collapse and to stabilize at a fair share of the		congestion collapse and to stabilize at a fair share of the
	bottleneck link capacity.		bottleneck link capacity.
	3.2. Bottleneck in Wi-Fi Network		3.2. Bottleneck in Wi-Fi Network
	The test cases in this section assume that the wired segment along		The test cases in this section assume that the wired segment along
	the media path is well-provisioned whereas the bottleneck exists over		the media path is well-provisioned, whereas the bottleneck exists
	the Wi-Fi access network. This is to mimic the application scenarios		over the Wi-Fi access network. This is to mimic the application
	typically encountered by users in an enterprise environment or at a		scenarios typically encountered by users in an enterprise environment
	coffee house.		or at a coffee house.
	3.2.1. Network topology		3.2.1. Network Topology
	Same as defined in Section 3.1.1		Same as defined in Section 3.1.1.
	3.2.2. Test/simulation setup		3.2.2. Test/Simulation Setup
	o Test duration: 120s		Test duration: 120 s
	o Wi-Fi network characteristics:		Wi-Fi network characteristics:
	* Radio propagation model: Log-distance path loss propagation		Radio propagation model: Log-distance path loss propagation model
	model (see [NS3WiFi])		(see [NS3WiFi])
	* PHY- and MAC-layer configuration: IEEE 802.11n		PHY- and MAC-layer configuration: IEEE 802.11n
	* MCS Index at 11: 16-QAM 1/2, Raw Data Rate at 52Mbps		MCS Index at 11: Raw data rate at 52 Mbps, 16-QAM (Quadrature
			amplitude modulation) and 1/2 coding rate
	o Wired path characteristics:		Wired path characteristics:
	* Path capacity: 100Mbps.		Path capacity: 100 Mbps
	* One-Way propagation delay: 50ms.		One-Way propagation delay: 50 ms
	* Maximum end-to-end jitter: 30ms.		Maximum end-to-end jitter: 30 ms
	* Bottleneck queue type: Drop tail.		Bottleneck queue type: Drop tail
	* Bottleneck queue size: 300ms.		Bottleneck queue size: 300 ms
	* Path loss ratio: 0%.		Path loss ratio: 0%
	o Application characteristics:		Application characteristics
	* Media Traffic:		Media traffic:
	+ Media type: Video		Media type: Video
	+ Media direction: See Section 3.2.3.		Media direction: See Section 3.2.3
	+ Number of media sources (N): See Section 3.2.3.		Number of media sources (N): See Section 3.2.3
	+ Media timeline:		Media timeline:
	- Start time: 0s.		Start time: 0 s
	- End time: 119s.		End time: 119 s
	* Competing traffic:		Competing traffic:
	+ Type of sources: long-lived TCP or CBR over UDP.		Type of sources: long-lived TCP or CBR over UDP
	+ Number of sources (M): See Section 3.2.3.		Number of sources (M): See Section 3.2.3
	+ Traffic direction: See Section 3.2.3.		Traffic direction: See Section 3.2.3
	+ Congestion control: Default TCP congestion control [RFC5681]		Congestion control: Default TCP congestion control [RFC5681]
	or constant-bit-rate (CBR) traffic over UDP.		or CBR traffic over UDP
	+ Traffic timeline: See Section 3.2.3.		Traffic timeline: See Section 3.2.3
	3.2.3. Typical test scenarios		3.2.3. Typical Test Scenarios
	This section describes a few test scenarios that are deemed as		This section describes a few test scenarios that are deemed as
	important for understanding the behavior of a candidate RTP-based		important for understanding the behavior of a candidate RTP-based
	congestion control scheme over a Wi-Fi network.		congestion control scheme over a Wi-Fi network.
	a. Multiple RTP-based media flows sharing the wireless downlink:		Multiple RTP-based media flows sharing the wireless downlink: N=16
	N=16 (all downlink); M = 0. This test case is for studying the		(all downlink); M=0. This test case is for studying the impact of
	impact of contention on the multiple concurrent media flows. For		contention on the multiple concurrent media flows. For an 802.11n
	an 802.11n network, given the MCS Index of 11 and the		network, given the MCS Index of 11 and the corresponding link rate
	corresponding link rate of 52Mbps, the total application-layer		of 52 Mbps, the total application-layer throughput (assuming
	throughput (assuming reasonable distance, low interference and		reasonable distance, low interference, and infrequent contentions
	infrequent contentions caused by competing streams) is around		caused by competing streams) is around 20 Mbps. A total of N=16
	20Mbps. A total of N=16 RTP-based media flows (with a maximum		RTP-based media flows (with a maximum rate of 1.5 Mbps each) are
	rate of 1.5Mbps each) are expected to saturate the wireless		expected to saturate the wireless interface in this experiment.
	interface in this experiment. Evaluation of a given candidate		Evaluation of a given candidate scheme should focus on whether the
	scheme should focus on whether the downlink media flows can		downlink media flows can stabilize at a fair share of the total
	stabilize at a fair share of the total application-layer		application-layer throughput.
	throughput.
	b. Multiple RTP-based media flows sharing the wireless uplink: N =		Multiple RTP-based media flows sharing the wireless uplink: N=16
	16 (all uplink); M = 0. When multiple clients attempt to		(all uplink); M=0. When multiple clients attempt to transmit
	transmit media packets uplink over the Wi-Fi network, they		media packets uplink over the Wi-Fi network, they introduce more
	introduce more frequent contentions and potential collisions.		frequent contentions and potential collisions. Per-flow
	Per-flow throughput is expected to be lower than that in the		throughput is expected to be lower than that in the previous
	previous downlink-only scenario. Evaluation of a given candidate		downlink-only scenario. Evaluation of a given candidate scheme
	scheme should focus on whether the uplink flows can stabilize at		should focus on whether the uplink flows can stabilize at a fair
	a fair share of the total application-layer throughput.		share of the total application-layer throughput.
	c. Multiple bi-directional RTP-based media flows: N = 16 (8 uplink		Multiple bidirectional RTP-based media flows: N=16 (8 uplink and 8
	and 8 downlink); M = 0. The goal of this test is to evaluate the		downlink); M=0. The goal of this test is to evaluate the
	performance of the candidate scheme in terms of bandwidth		performance of the candidate scheme in terms of bandwidth fairness
	fairness between uplink and downlink flows.		between uplink and downlink flows.
	d. Multiple bi-directional RTP-based media flows with on-off CBR		Multiple bidirectional RTP-based media flows with on-off CBR
	traffic over UDP: N = 16 (8 uplink and 8 downlink); M = 5		traffic over UDP: N=16 (8 uplink and 8 downlink); M=5 (uplink). The
	(uplink). The goal of this test is to evaluate the adaptation		goal of this test is to evaluate the adaptation behavior of the
	behavior of the candidate scheme when its available bandwidth		candidate scheme when its available bandwidth changes due to the
	changes due to the departure of background traffic. The		departure of background traffic. The background traffic consists
	background traffic consists of several (e.g., M=5) CBR flows		of several (e.g., M=5) CBR flows transported over UDP. These
	transported over UDP. These background flows are ON at time		background flows are ON at time t=0-60s and OFF at time t=61-120s.
	t=0-60s and OFF at time t=61-120s.
	e. Multiple bi-directional RTP-based media flows with off-on CBR		Multiple bidirectional RTP-based media flows with off-on CBR
	traffic over UDP: N = 16 (8 uplink and 8 downlink); M = 5		traffic over UDP: N=16 (8 uplink and 8 downlink); M=5 (uplink). The
	(uplink). The goal of this test is to evaluate the adaptation		goal of this test is to evaluate the adaptation behavior of the
	behavior of the candidate scheme when its available bandwidth		candidate scheme when its available bandwidth changes due to the
	changes due to the arrival of background traffic. The background		arrival of background traffic. The background traffic consists of
	traffic consists of several (e.g., M=5) parallel CBR flows		several (e.g., M=5) parallel CBR flows transported over UDP.
	transported over UDP. These background flows are OFF at time		These background flows are OFF at time t=0-60s and ON at times
	t=0-60s and ON at times t=61-120s.		t=61-120s.
	f. Multiple bi-directional RTP-based media flows in the presence of		Multiple bidirectional RTP-based media flows in the presence of
	background TCP traffic: N=16 (8 uplink and 8 downlink); M = 5		background TCP traffic: N=16 (8 uplink and 8 downlink); M=5
	(uplink). The goal of this test is to evaluate how RTP-based		(uplink). The goal of this test is to evaluate how RTP-based
	media flows compete against TCP over a congested Wi-Fi network		media flows compete against TCP over a congested Wi-Fi network for
	for a given candidate scheme. TCP flows have start time at t=40s		a given candidate scheme. TCP flows have start time at t=40s and
	and end time at t=80s.		end time at t=80s.
	g. Varying number of RTP-based media flows: A series of tests can be		Varying number of RTP-based media flows: A series of tests can be
	carried out for the above test cases with different values of N,		carried out for the above test cases with different values of N,
	e.g., N = [4, 8, 12, 16, 20]. The goal of this test is to		e.g., N=[4, 8, 12, 16, 20]. The goal of this test is to evaluate
	evaluate how a candidate scheme responds to varying traffic load/		how a candidate scheme responds to varying traffic load/demand
	demand over a congested Wi-Fi network. The start times of the		over a congested Wi-Fi network. The start times of the media
	media flows are randomly distributes within a window of t=0-10s;		flows are randomly distributed within a window of t=0-10s; their
	their end times are randomly distributed within a window of		end times are randomly distributed within a window of t=110-120s.
	t=110-120s.
	3.2.4. Expected behavior		3.2.4. Expected Behavior
	o Multiple downlink RTP-based media flows: each media flow is		Multiple downlink RTP-based media flows: Each media flow is expected
	expected to get its fair share of the total bottleneck link		to get its fair share of the total bottleneck link bandwidth.
	bandwidth. Overall bandwidth usage should not be significantly		Overall bandwidth usage should not be significantly lower than
	lower than that experienced by the same number of concurrent		that experienced by the same number of concurrent downlink TCP
	downlink TCP flows. In other words, the behavior of multiple		flows. In other words, the behavior of multiple concurrent TCP
	concurrent TCP flows will be used as a performance benchmark for		flows will be used as a performance benchmark for this test
	this test scenario. The end-to-end delay and packet loss ratio		scenario. The end-to-end delay and packet loss ratio experienced
	experienced by each flow should be within an acceptable range for		by each flow should be within an acceptable range for real-time
	real-time multimedia applications.		multimedia applications.
	o Multiple uplink RTP-based media flows: overall bandwidth usage by		Multiple uplink RTP-based media flows: Overall bandwidth usage by
	all media flows should not be significantly lower than that		all media flows should not be significantly lower than that
	experienced by the same number of concurrent uplink TCP flows. In		experienced by the same number of concurrent uplink TCP flows. In
	other words, the behavior of multiple concurrent TCP flows will be		other words, the behavior of multiple concurrent TCP flows will be
	used as a performance benchmark for this test scenario.		used as a performance benchmark for this test scenario.
	o Multiple bi-directional RTP-based media flows with dynamic		Multiple bidirectional RTP-based media flows with dynamic
	background traffic carrying CBR flows over UDP: the media flows		background traffic carrying CBR flows over UDP: The media flows are
	are expected to adapt in a timely fashion to the changes in		expected to adapt in a timely fashion to the changes in available
	available bandwidth introduced by the arrival/departure of		bandwidth introduced by the arrival/departure of background
	background traffic.		traffic.
	o Multiple bi-directional RTP-based media flows with dynamic		Multiple bidirectional RTP-based media flows with dynamic
	background traffic over TCP: during the presence of TCP background		background traffic over TCP: During the presence of TCP background
	flows, the overall bandwidth usage by all media flows should not		flows, the overall bandwidth usage by all media flows should not
	be significantly lower than those achieved by the same number of		be significantly lower than those achieved by the same number of
	bi-directional TCP flows. In other words, the behavior of		bidirectional TCP flows. In other words, the behavior of multiple
	multiple concurrent TCP flows will be used as a performance		concurrent TCP flows will be used as a performance benchmark for
	benchmark for this test scenario. All downlink media flows are		this test scenario. All downlink media flows are expected to
	expected to obtain similar bandwidth as each other. The		obtain similar bandwidth as each other. The throughput of each
	throughput of each media flow is expected to decrease upon the		media flow is expected to decrease upon the arrival of TCP
	arrival of TCP background traffic and, conversely, increase upon		background traffic and, conversely, increase upon their departure.
	their departure. Both reactions should occur in a timely fashion,		Both reactions should occur in a timely fashion, for example,
	for example, within 10s of seconds.		within 10s of seconds.
	o Varying number of bi-directional RTP-based media flows: the test		Varying number of bidirectional RTP-based media flows: The test
	results for varying values of N -- while keeping all other		results for varying values of N -- while keeping all other
	parameters constant -- is expected to show steady and stable per-		parameters constant -- is expected to show steady and stable per-
	flow throughput for each value of N. The average throughput of		flow throughput for each value of N. The average throughput of
	all media flows is expected to stay constant around the maximum		all media flows is expected to stay constant around the maximum
	rate when N is small, then gradually decrease with increasing		rate when N is small, then gradually decrease with increasing
	value of N till it reaches the minimum allowed rate, beyond which		value of N till it reaches the minimum allowed rate, beyond which
	the offered load to the Wi-Fi network exceeds its capacity (i.e.,		the offered load to the Wi-Fi network exceeds its capacity (i.e.,
	with a very large value of N).		with a very large value of N).
	3.3. Other Potential Test Cases		3.3. Other Potential Test Cases
	skipping to change at page 19, line 46 ¶		skipping to change at line 884 ¶
	classes (or Access Categories). RTP-based real-time media flows		classes (or Access Categories). RTP-based real-time media flows
	should achieve better performance in terms of lower delay and fewer		should achieve better performance in terms of lower delay and fewer
	packet losses with EDCA/WMM enabled when competing against non-		packet losses with EDCA/WMM enabled when competing against non-
	interactive background traffic such as file transfers. When most of		interactive background traffic such as file transfers. When most of
	the traffic over Wi-Fi is dominated by media, however, turning on WMM		the traffic over Wi-Fi is dominated by media, however, turning on WMM
	may degrade performance since all media flows now attempt to access		may degrade performance since all media flows now attempt to access
	the wireless transmission medium more aggressively, thereby causing		the wireless transmission medium more aggressively, thereby causing
	more frequent collisions and collision-induced losses. This is a		more frequent collisions and collision-induced losses. This is a
	topic worthy of further investigation.		topic worthy of further investigation.
	3.3.2. Effect of heterogeneous link rates		3.3.2. Effect of Heterogeneous Link Rates
	As discussed in [Heusse2003], the presence of clients operating over		As discussed in [Heusse2003], the presence of clients operating over
	slow PHY-layer link rates (e.g., a legacy 802.11b device) connected		slow PHY-layer link rates (e.g., a legacy 802.11b device) connected
	to a modern network may adversely impact the overall performance of		to a modern network may adversely impact the overall performance of
	the network. Additional test cases can be devised to evaluate the		the network. Additional test cases can be devised to evaluate the
	effect of clients with heterogeneous link rates on the performance of		effect of clients with heterogeneous link rates on the performance of
	the candidate congestion control algorithm. Such test cases, for		the candidate congestion control algorithm. Such test cases, for
	instance, can specify that the PHY-layer link rates for all clients		instance, can specify that the PHY-layer link rates for all clients
	span over a wide range (e.g., 2Mbps to 54Mbps) for investigating its		span over a wide range (e.g., 2 Mbps to 54 Mbps) for investigating
	effect on the congestion control behavior of the real-time		its effect on the congestion control behavior of the real-time
	interactive applications.		interactive applications.
	4. IANA Considerations		4. IANA Considerations
	This memo includes no request to IANA.		This document has no IANA actions.
	5. Security Considerations		5. Security Considerations
	The security considerations in [I-D.ietf-rmcat-eval-criteria] and the		The security considerations in [RFC8868] and the relevant congestion
	relevant congestion control algorithms apply. The principles for		control algorithms apply. The principles for congestion control are
	congestion control are described in [RFC2914], and in particular, any		described in [RFC2914], and in particular, any new method must
	new method must implement safeguards to avoid congestion collapse of		implement safeguards to avoid congestion collapse of the Internet.
	the Internet.
	Given the difficulty of deterministic wireless testing, it is		Given the difficulty of deterministic wireless testing, it is
	recommended and expected that the tests described in this document		recommended and expected that the tests described in this document
	would be done via simulations. However, in the case where these test		would be done via simulations. However, in the case where these test
	cases are carried out in a testbed setting, the evaluation should		cases are carried out in a testbed setting, the evaluation should
	take place in a controlled lab environment. In the testbed, the		take place in a controlled lab environment. In the testbed, the
	applications, simulators and network nodes ought to be well-behaved		applications, simulators, and network nodes ought to be well-behaved
	and should not impact the desired results. It is important to take		and should not impact the desired results. It is important to take
	appropriate caution to avoid leaking non-responsive traffic with		appropriate caution to avoid leaking nonresponsive traffic with
	unproven congestion avoidance behavior onto the open Internet.		unproven congestion avoidance behavior onto the open Internet.
	6. Contributors		6. References
	The following individuals contributed to the design, implementation,
	and verification of the proposed test cases during earlier stages of
	this work. They have helped to validate and substantially improve
	this specification.
	Ingemar Johansson, <ingemar.s.johansson@ericsson.com> of Ericsson AB
	contributing to the description and validation of cellular test cases
	during the earlier stage of this draft.
	Wei-Tian Tan, <dtan2@cisco.com>, of Cisco Systems designed and set up
	a Wi-Fi testbed for evaluating parallel video conferencing streams,
	based upon which proposed Wi-Fi test cases are described. He also
	recommended additional test cases to consider, such as the impact of
	EDCA/WMM usage.
	Michael A. Ramalho, <mar42@cornell.edu> of AcousticComms Consulting
	(previously at Cisco Systems) applied learnings from Cisco's internal
	experimentation to the early versions of the draft. He also worked
	on validating the proposed test cases in a VM-based lab setting.
	7. Acknowledgments
	The authors would like to thank Tomas Frankkila, Magnus Westerlund,
	Kristofer Sandlund, Sergio Mena de la Cruz, and Mirja Kuehlewind for
	their valuable inputs and review comments regarding this draft.
	8. References
	8.1. Normative References		6.1. Normative References
	[HO-deploy-3GPP]		[HO-deploy-3GPP]
	TS 25.814, 3GPP., "Physical layer aspects for evolved		3GPP, "Physical layer aspects for evolved Universal
	Universal Terrestrial Radio Access (UTRA)", October 2006,		Terrestrial Radio Access (UTRA)", TS 25.814, October 2006,
	<http://www.3gpp.org/ftp/specs/		<http://www.3gpp.org/ftp/specs/
	archive/25_series/25.814/25814-710.zip>.		archive/25_series/25.814/25814-710.zip>.
	[I-D.ietf-rmcat-eval-criteria]
	Singh, V., Ott, J., and S. Holmer, "Evaluating Congestion
	Control for Interactive Real-time Media", draft-ietf-
	rmcat-eval-criteria-13 (work in progress), March 2020.
	[I-D.ietf-rmcat-eval-test]
	Sarker, Z., Singh, V., Zhu, X., and M. Ramalho, "Test
	Cases for Evaluating RMCAT Proposals", draft-ietf-rmcat-
	eval-test-10 (work in progress), May 2019.
	[IEEE802.11]		[IEEE802.11]
	IEEE, "Standard for Information technology--		IEEE, "Standard for Information technology--
	Telecommunications and information exchange between		Telecommunications and information exchange between
	systems Local and metropolitan area networks--Specific		systems Local and metropolitan area networks--Specific
	requirements Part 11: Wireless LAN Medium Access Control		requirements Part 11: Wireless LAN Medium Access Control
	(MAC) and Physical Layer (PHY) Specifications", 2012.		(MAC) and Physical Layer (PHY) Specifications",
			IEEE 802.11-2012,
			<https://ieeexplore.ieee.org/document/7786995>.
	[NS3WiFi] "Wi-Fi Channel Model in ns-3 Simulator",		[NS3WiFi] "ns3::YansWifiChannel Class Reference",
	<https://www.nsnam.org/doxygen/		<https://www.nsnam.org/doxygen/
	classns3_1_1_yans_wifi_channel.html>.		classns3_1_1_yans_wifi_channel.html>.
	[RFC5681] Allman, M., Paxson, V., and E. Blanton, "TCP Congestion		[RFC5681] Allman, M., Paxson, V., and E. Blanton, "TCP Congestion
	Control", RFC 5681, DOI 10.17487/RFC5681, September 2009,		Control", RFC 5681, DOI 10.17487/RFC5681, September 2009,
	<https://www.rfc-editor.org/info/rfc5681>.		<https://www.rfc-editor.org/info/rfc5681>.
	[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC		[RFC8867] Sarker, Z., Singh, V., Zhu, X., and M. Ramalho, "Test
	2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,		Cases for Evaluating Congestion Control for Interactive
	May 2017, <https://www.rfc-editor.org/info/rfc8174>.		Real-Time Media", RFC 8867, DOI 10.17487/RFC8867, January
			2021, <https://www.rfc-editor.org/info/rfc8867>.
	8.2. Informative References		[RFC8868] Singh, V., Ott, J., and S. Holmer, "Evaluating Congestion
			Control for Interactive Real-Time Media", RFC 8868,
			DOI 10.17487/RFC8868, January 2021,
			<https://www.rfc-editor.org/info/rfc8868>.
			6.2. Informative References
	[Heusse2003]		[Heusse2003]
	Heusse, M., Rousseau, F., Berger-Sabbatel, G., and A.		Heusse, M., Rousseau, F., Berger-Sabbatel, G., and A.
	Duda, "Performance anomaly of 802.11b", in Proc. 23th		Duda, "Performance anomaly of 802.11b", IEEE INFOCOM 2003,
	Annual Joint Conference of the IEEE Computer and		Twenty-second Annual Joint Conference of the IEEE Computer
	Communications Societies, (INFOCOM'03), March 2003.		and Communications Societies,
			DOI 10.1109/INFCOM.2003.1208921, March 2003,
			<https://ieeexplore.ieee.org/document/1208921>.
	[HO-def-3GPP]		[HO-def-3GPP]
	TR 21.905, 3GPP., "Vocabulary for 3GPP Specifications",		3GPP, "Vocabulary for 3GPP Specifications", 3GPP
	December 2009, <http://www.3gpp.org/ftp/specs/		TS 21.905, December 2009, <http://www.3gpp.org/ftp/specs/
	archive/21_series/21.905/21905-940.zip>.		archive/21_series/21.905/21905-940.zip>.
	[HO-LTE-3GPP]		[HO-LTE-3GPP]
	TS 36.331, 3GPP., "E-UTRA- Radio Resource Control (RRC);		3GPP, "Evolved Universal Terrestrial Radio Access
	Protocol specification", December 2011,		(E-UTRA); Radio Resource Control (RRC); Protocol
			specification", 3GPP TS 36.331, December 2011,
	<http://www.3gpp.org/ftp/specs/		<http://www.3gpp.org/ftp/specs/
	archive/36_series/36.331/36331-990.zip>.		archive/36_series/36.331/36331-990.zip>.
	[HO-UMTS-3GPP]		[HO-UMTS-3GPP]
	TS 25.331, 3GPP., "Radio Resource Control (RRC); Protocol		3GPP, "Radio Resource Control (RRC); Protocol
	specification", December 2011,		specification", 3GPP TS 25.331, December 2011,
	<http://www.3gpp.org/ftp/specs/		<http://www.3gpp.org/ftp/specs/
	archive/25_series/25.331/25331-990.zip>.		archive/25_series/25.331/25331-990.zip>.
	[NS-2] "ns-2", December 2014,		[NS-2] "ns-2", December 2014,
	<http://nsnam.sourceforge.net/wiki/index.php/Main_Page>.		<http://nsnam.sourceforge.net/wiki/index.php/Main_Page>.
	[NS-3] "ns-3 Network Simulator", <https://www.nsnam.org/>.		[NS-3] "ns-3 Network Simulator", <https://www.nsnam.org/>.
	[QoS-3GPP]		[QoS-3GPP] 3GPP, "Policy and charging control architecture", 3GPP
	TS 23.203, 3GPP., "Policy and charging control		TS 23.203, June 2011, <http://www.3gpp.org/ftp/specs/
	architecture", June 2011, <http://www.3gpp.org/ftp/specs/
	archive/23_series/23.203/23203-990.zip>.		archive/23_series/23.203/23203-990.zip>.
	[RFC2914] Floyd, S., "Congestion Control Principles", BCP 41,		[RFC2914] Floyd, S., "Congestion Control Principles", BCP 41,
	RFC 2914, DOI 10.17487/RFC2914, September 2000,		RFC 2914, DOI 10.17487/RFC2914, September 2000,
	<https://www.rfc-editor.org/info/rfc2914>.		<https://www.rfc-editor.org/info/rfc2914>.
			Contributors
			The following individuals contributed to the design, implementation,
			and verification of the proposed test cases during earlier stages of
			this work. They have helped to validate and substantially improve
			this specification.
			Ingemar Johansson <ingemar.s.johansson@ericsson.com> of Ericsson AB
			contributed to the description and validation of cellular test cases
			during the earlier stage of this document.
			Wei-Tian Tan <dtan2@cisco.com> of Cisco Systems designed and set up a
			Wi-Fi testbed for evaluating parallel video conferencing streams,
			based upon which proposed Wi-Fi test cases are described. He also
			recommended additional test cases to consider, such as the impact of
			EDCA/WMM usage.
			Michael A. Ramalho <mar42@cornell.edu> of AcousticComms Consulting
			(previously at Cisco Systems) applied lessons from Cisco's internal
			experimentation to the draft versions of the document. He also
			worked on validating the proposed test cases in a virtual-machine-
			based lab setting.
			Acknowledgments
			The authors would like to thank Tomas Frankkila, Magnus Westerlund,
			Kristofer Sandlund, Sergio Mena de la Cruz, and Mirja Kühlewind for
			their valuable inputs and review comments regarding this document.
	Authors' Addresses		Authors' Addresses
	Zaheduzzaman Sarker		Zaheduzzaman Sarker
	Ericsson AB		Ericsson AB
	Laboratoriegraend 11		Torshamnsgatan 23
	Luleae 97753		SE-164 83 Stockholm
	Sweden		Sweden
	Phone: +46 107173743		Phone: +46 10 717 37 43
	Email: zaheduzzaman.sarker@ericsson.com		Email: zaheduzzaman.sarker@ericsson.com
	Xiaoqing Zhu		Xiaoqing Zhu
	Cisco Systems		Cisco Systems
	12515 Research Blvd., Building 4		Building 4
	Austin, TX 78759		12515 Research Blvd
	USA		Austin, TX 78759
			United States of America
	Email: xiaoqzhu@cisco.com		Email: xiaoqzhu@cisco.com
	Jiantao Fu		Jiantao Fu
	Cisco Systems		Cisco Systems
	771 Alder Drive		771 Alder Drive
	Milpitas, CA 95035		Milpitas, CA 95035
	USA		United States of America
	Email: jianfu@cisco.com		Email: jianfu@cisco.com
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