rfc9797.original		rfc9797.txt
	Internet Engineering Task Force J. Henry		Internet Engineering Task Force (IETF) J. Henry
	Internet-Draft Cisco Systems		Request for Comments: 9797 Cisco Systems
	Intended status: Informational Y. Lee		Category: Informational Y. Lee
	Expires: 23 June 2025 Comcast		ISSN: 2070-1721 Comcast
	20 December 2024		June 2025
	Randomized and Changing MAC Address: Context, Network Impacts, and Use		Randomized and Changing Media Access Control (MAC) Addresses: Context,
	Cases		Network Impacts, and Use Cases
	draft-ietf-madinas-use-cases-19
	Abstract		Abstract
	To limit the privacy issues created by the association between a		To limit the privacy issues created by the association between a
	device, its traffic, its location, and its user in [IEEE_802]		device, its traffic, its location, and its user in IEEE 802 networks,
	networks, client and client Operating System vendors have started		client and client Operating System vendors have started implementing
	implementing MAC address randomization. This technology is		Media Access Control (MAC) address randomization. This technology is
	particularly important in Wi-Fi [IEEE_802.11] networks due to the		particularly important in Wi-Fi networks (defined in IEEE 802.11) due
	over-the-air medium and device mobility. When such randomization		to the over-the-air medium and device mobility. When such
	happens, some in-network states may break, which may affect network		randomization happens, some in-network states may break, which may
	connectivity and user experience. At the same time, devices may		affect network connectivity and user experience. At the same time,
	continue using other stable identifiers, defeating the MAC address		devices may continue using other stable identifiers, defeating the
	randomization purposes.		purpose of MAC address randomization.
	This document lists various network environments and a range of		This document lists various network environments and a range of
	network services that may be affected by such randomization. This		network services that may be affected by such randomization. This
	document then examines settings where the user experience may be		document then examines settings where the user experience may be
	affected by in-network state disruption. Last, this document		affected by in-network state disruption. Last, this document
	examines two existing frameworks to maintain user privacy while		examines some existing frameworks that maintain user privacy while
	preserving user quality of experience and network operation		preserving user quality of experience and network operation
	efficiency.		efficiency.
	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
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			approved by the IESG are candidates for any level of Internet
			Standard; see Section 2 of RFC 7841.
	This Internet-Draft will expire on 23 June 2025.		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/rfc9797.
	Copyright Notice		Copyright Notice
	Copyright (c) 2024 IETF Trust and the persons identified as the		Copyright (c) 2025 IETF Trust and the persons identified as the
	document authors. All rights reserved.		document authors. All rights reserved.
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	Table of Contents		Table of Contents
	1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2		1. Introduction
	2. MAC Address as Identity: User vs. Device . . . . . . . . . . 4		2. MAC Address as Identity: User vs. Device
	2.1. Privacy of MAC Address . . . . . . . . . . . . . . . . . 6		2.1. Privacy of MAC Addresses
	3. The Actors: Network Functional Entities and Human Entities . 6		3. The Actors: Network Functional Entities and Human Entities
	3.1. Network Functional Entities . . . . . . . . . . . . . . . 7		3.1. Network Functional Entities
	3.2. Human-related Entities . . . . . . . . . . . . . . . . . 8		3.2. Human-Related Entities
	4. Degrees of Trust . . . . . . . . . . . . . . . . . . . . . . 9		4. Degrees of Trust
	5. Environment . . . . . . . . . . . . . . . . . . . . . . . . . 10		5. Environments
	6. Network Services . . . . . . . . . . . . . . . . . . . . . . 13		6. Network Services
	6.1. Device Identification and Associated Problems . . . . . . 13		6.1. Device Identification and Associated Problems
	7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 16		7. IANA Considerations
	8. Security Considerations . . . . . . . . . . . . . . . . . . . 16		8. Security Considerations
	9. Informative References . . . . . . . . . . . . . . . . . . . 16		9. Informative References
	Appendix A. Existing Frameworks . . . . . . . . . . . . . . . . 18		Appendix A. Existing Frameworks
	A.1. 802.1X with WPA2 / WPA3 . . . . . . . . . . . . . . . . . 18		A.1. IEEE 802.1X with WPA2 / WPA3
	A.2. OpenRoaming . . . . . . . . . . . . . . . . . . . . . . . 19		A.2. OpenRoaming
	A.3. Proprietary RCM schemes . . . . . . . . . . . . . . . . . 20		A.3. Proprietary RCM Schemes
	Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 20		Authors' Addresses
	1. Introduction		1. Introduction
	When MAC-Address was first introduced in [IEEE_802] Standard, it was		When the MAC address was first introduced in [IEEE_802], it was used
	used in wired Ethernet network [IEEE_802.3]. Due to the nature of		in wired Ethernet networks [IEEE_802.3]. Due to the nature of wired
	the wired network, devices were relatively stationary and the		networks, devices were relatively stationary, and the physical
	physical connection imposed a boundary to restrict attackers to		connection imposed a boundary that restricted attackers from easily
	easily access the network data. But [IEEE_802.11] (Wi-Fi) brought		accessing the network data. However, [IEEE_802.11] (Wi-Fi) brought
	new challenges when it was introduced.		new challenges when it was introduced.
	The flexibility of Wi-Fi technology has revolutionized communications		The flexibility of Wi-Fi technology has revolutionized communications
	and become the preferred, and sometimes the only technology used by		and become the preferred, and sometimes the only, technology used by
	devices such as laptops, tablets, and Internet of Things (IoT)		devices such as laptops, tablets, and Internet of Things (IoT)
	devices. Wi-Fi is an over-the-air medium that allows attackers with		devices. Wi-Fi is an over-the-air medium that allows attackers with
	surveillance equipment to monitor WLAN packets and track the activity		surveillance equipment to monitor WLAN packets and track the activity
	of WLAN devices. It is also sometimes possible for attackers to		of WLAN devices. It is also sometimes possible for attackers to
	monitor the WLAN packets behind the Wi-Fi Access Point (AP) over the		monitor the WLAN packets behind the Wi-Fi Access Point (AP) over the
	wired Ethernet. Once the association between a device and its user		wired Ethernet. Once the association between a device and its user
	is made, identifying the device and its activity is sufficient to		is made, identifying the device and its activity is sufficient to
	deduce information about what the user is doing, without the user's		deduce information about what the user is doing, without the user's
	consent.		consent.
	skipping to change at page 3, line 24 ¶		skipping to change at line 117 ¶
	MAC addresses (RCM). By randomizing the MAC address, it becomes		MAC addresses (RCM). By randomizing the MAC address, it becomes
	harder to use the MAC address to construct a persistent association		harder to use the MAC address to construct a persistent association
	between a flow of data packets and a device, assuming no other		between a flow of data packets and a device, assuming no other
	visible unique identifiers or stable patterns are in use. When		visible unique identifiers or stable patterns are in use. When
	individual devices are no longer easily identifiable, it also becomes		individual devices are no longer easily identifiable, it also becomes
	difficult to associate a series of network packet flows in a		difficult to associate a series of network packet flows in a
	prolonged period with a particular individual using one specific		prolonged period with a particular individual using one specific
	device if the device randomizes the MAC address governed by the OS		device if the device randomizes the MAC address governed by the OS
	privacy policies.		privacy policies.
	However, such address change may affect the user experience and the		However, such address changes may affect the user experience and the
	efficiency of legitimate network operations. For a long time,		efficiency of legitimate network operations. For a long time,
	network designers and implementers relied on the assumption that a		network designers and implementers relied on the assumption that a
	given machine, in a network implementing [IEEE_802] technologies,		given machine, in a network implementing IEEE 802 technologies
	would be represented by a unique network MAC address that would not		[IEEE_802], would be represented by a unique network MAC address that
	change over time. When this assumption is broken, network		would not change over time. When this assumption is broken, network
	communication may be disrupted. For example, sessions established		communication may be disrupted. For example, sessions established
	between the end-device and network services may break and packets in		between the end device and the network services may break, and
	transit may suddenly be lost. If multiple clients implement		packets in transit may suddenly be lost. If multiple clients
	aggressive (e.g., once an hour or shorter) MAC address randomization		implement aggressive (e.g., once an hour or shorter) MAC address
	without coordination with network services, some network services		randomization without coordination with network services, some
	such as MAC address cache in the AP and the upstream layer-2 switch		network services, such as MAC address caching in the AP and the
	may not be able to handle the load that may result in unexpected		upstream Layer 2 switch, may not be able to handle the load, which
	network interruption.		may result in an unexpected network interruption.
	At the same time, some network services rely on the end station (as		At the same time, some network services rely on the end station (as
	defined by the [IEEE_802] Standard, also called in this document		defined by [IEEE_802], also called in this document device, or
	device, or machine) providing an identifier, which can be the MAC		machine) providing an identifier, which can be the MAC address or
	address or another value. If the client implements MAC address		another value. If the client implements MAC address randomization
	randomization but continues sending the same static identifier, then		but continues sending the same static identifier, then the
	the association between a stable identifier and the station continues		association between a stable identifier and the station continues
	despite the RCM scheme. There may be environments where such		despite the RCM scheme. There may be environments where such
	continued association is desirable, but others where user privacy has		continued association is desirable, but there may be others where
	more value than any continuity of network service state.		user privacy has more value than any continuity of network service
			state.
	It is useful for implementations of client and network devices to		It is useful for implementations of client and network devices to
	enumerate services that may be affected by RCM and evaluate possible		enumerate services that may be affected by RCM and to evaluate
	framework to maintain both the quality of user experience and network		possible frameworks to maintain both the quality of user experience
	efficiency while RCM happens, and user privacy is strengthened. This		and network efficiency while RCM happens and user privacy is
	document presents these assessments and recommendations.		strengthened. This document presents these assessments and
			recommendations.
	Although this document mainly discusses MAC-Address randomization in		Although this document mainly discusses MAC address randomization in
	Wi-Fi [IEEE_802.11] networks, same principles can be easily extended		Wi-Fi networks [IEEE_802.11], the same principles can be easily
	to any [IEEE_802.3] networks.		extended to any IEEE 802.3 networks [IEEE_802.3].
	This document is organized as follows. Section 2 discusses the		This document is organized as follows:
	current status of using MAC address as identity. Section 3 discusses
	various actors in the network that will be impacted by MAC address		* Section 2 discusses the current status of using MAC address as
	randomization. Section 4 examines the degrees of trust between		identity.
	personal devices and the entities at play in a network domain.
	Section 5 discusses various network environments that will be		* Section 3 discusses various actors in the network that will be
	impacted. Section 6 analyzes some existing network services that		impacted by MAC address randomization.
	will be impacted. Finally, Appendix A includes some frameworks that
	are being worked on.		* Section 4 examines the degrees of trust between personal devices
			and the entities at play in a network domain.
			* Section 5 discusses various network environments that will be
			impacted.
			* Section 6 analyzes some existing network services that will be
			impacted.
			* Appendix A includes some existing frameworks.
	2. MAC Address as Identity: User vs. Device		2. MAC Address as Identity: User vs. Device
	The Media Access Control (MAC) layer of IEEE 802.3 [IEEE_802.3]		In IEEE 802.3 technologies [IEEE_802.3], the Media Access Control
	technologies define rules to control how a device accesses the shared		(MAC) layer defines rules to control how a device accesses the shared
	medium. In a network where a machine can communicate with one or		medium. In a network where a machine can communicate with one or
	more other machines, one such rule is that each machine needs to be		more other machines, one such rule is that each machine needs to be
	identified either as the target destination of a message or as the		identified as either the target destination of a message or the
	source of a message (and the target destination of the answer).		source of a message (and the target destination of the answer).
	Initially intended as a 48-bit (6 octets) value in the first versions		Initially intended as a 48-bit (6-octet) value in the first versions
	of the [IEEE_802.3] Standard, other Standards under the [IEEE_802.3]		of [IEEE_802.3], other standards under the IEEE 802.3 umbrella allow
	umbrella allow this address to take an extended format of 64 bits (8		this address to take an extended format of 64 bits (8 octets), which
	octets) which enable a larger number of MAC addresses to coexist as		enabled a larger number of MAC addresses to coexist as IEEE 802.3
	the 802.3 technologies became widely adopted.		technologies became widely adopted.
	Regardless of the address length, different networks have different		Regardless of the address length, different networks have different
	needs, and several bits of the first octet are reserved for specific		needs, and several bits of the first octet are reserved for specific
	purposes. In particular, the first bit is used to identify the		purposes. In particular, the first bit is used to identify the
	destination address as an individual (bit set to 0) or a group		destination address as an individual (bit set to 0) or a group
	address (bit set to 1). The second bit, called the Universally or		address (bit set to 1). The second bit, called the Universal/Local
	Locally Administered (U/L) Address Bit, indicates whether the address		(U/L) address bit, indicates whether the address has been assigned by
	has been assigned by a universal or local administrator. Universally		a universal or local administrator. Universally administered
	administered addresses have this bit set to 0. If this bit is set to		addresses have this bit set to 0. If this bit is set to 1, the
	1, the entire address is considered locally administered (clause 8.4		entire address is considered to be locally administered (see Clause
	of [IEEE_802]). Note that universally administered MAC addresses are		8.4 of [IEEE_802]). Note that universally administered MAC addresses
	required to register to IEEE while locally administered MAC addresses		are required to register to IEEE, while locally administered MAC
	are not.		addresses are not.
	The intent of this provision is important for the present document.		The intent of this provision is important for the present document.
	The [IEEE_802] Standard recognized that some devices (e.g., smart		[IEEE_802] recognizes that some devices (e.g., smart thermostats) may
	thermostats) may never change their attachment network and will not		never change their attachment network and will not need a globally
	need a globally unique MAC address to prevent address collision		unique MAC address to prevent address collision against any other
	against any other device in any other network. The U/L bit can be		device in any other network. The U/L bit can be set to signal to the
	set to signal to the network that the MAC Address is intended to be		network that the MAC address is intended to be locally unique (not
	locally unique (not globally unique). [IEEE_802] did not initially		globally unique). [IEEE_802] did not initially define the MAC
	define the MAC Address allocation schema when the U/L bit is set to		address allocation schema when the U/L bit is set to 1. It states
	1. It states the address must be unique in a given broadcast domain		the address must be unique in a given broadcast domain (i.e., the
	(i.e., the space where the MAC addresses of devices are visible to		space where the MAC addresses of devices are visible to one another).
	one another).
	It is also important to note that the purpose of the Universal		It is also important to note that the purpose of the universal
	version of the address was to avoid collisions and confusion, as any		version of the address was to avoid collisions and confusion, as any
	machine could connect to any network, and each machine needs to		machine could connect to any network, and each machine needs to
	determine if it is the intended destination of a message or its		determine if it is the intended destination of a message or its
	response. Clause 8.4 of [IEEE_802] reminds network designers and		response. Clause 8.4 of [IEEE_802] reminds network designers and
	operators that all potential members of a network need to have a		operators that all potential members of a network need to have a
	unique identifier in that network (if they are going to coexist in		unique identifier in that network (if they are going to coexist in
	the network without confusion on which machine is the source or		the network without confusion on which machine is the source or
	destination or any message). The advantage of an administrated		destination or any message). The advantage of an administrated
	address is that a node with such an address can be attached to any		address is that a node with such an address can be attached to any
	Local Area Network (LAN) in the world with an assurance that its		Local Area Network (LAN) in the world with an assurance that its
	address is unique in that network.		address is unique in that network.
	With the rapid development of wireless technologies and mobile		With the rapid development of wireless technologies and mobile
	devices, this scenario became very common. With a vast majority of		devices, this scenario became very common. With a vast majority of
	networks implementing [IEEE_802] radio technologies at the access,		networks implementing IEEE 802 radio technologies [IEEE_802] at the
	the MAC address of a wireless device can appear anywhere on the		access, the MAC address of a wireless device can appear anywhere on
	planet and collisions should still be avoided. However, the same		the planet and collisions should still be avoided. However, the same
	evolution brought the distinction between two types of devices that		evolution brought the distinction between two types of devices that
	the [IEEE_802] Standard generally referred to as ‘nodes in a		[IEEE_802] generally refers to as "nodes in a network" (see
	network’. Their definition is found in the [IEEE_802E] Recommended		Section 6.2 of [IEEE_802E] for definitions of these devices):
	Practice stated in Section 6.2 of [IEEE_802].
	1. Shared Service Device, whose functions are used by enough people		Shared Service Device: A device used by enough people that the
	that the device itself, functions, or its traffic cannot be		device itself, its functions, or its traffic cannot be associated
	associated with a single or small group of people. Examples of		with a single or small group of people. Examples of such devices
	such devices include switches in a dense network, [IEEE_802.11]		include switches in a dense network, (WLAN) access points
	(WLAN) access points in a crowded airport, task-specific device		[IEEE_802.11] in a crowded airport, and task-specific devices
	(e.g., barcode scanners).		(e.g., barcode scanners).
	2. Personal Device, which is a machine or node primarily used by a		Personal Device: A machine or node primarily used by a single person
	single person or small group of people, and so that any		or small group of people, so that any identification of the device
	identification of the device or its traffic can also be		or its traffic can also be associated with the identification of
	associated with the identification of the primary user or their		the primary user or their online activity.
	online activity.
	Identifying the device is trivial if it has a unique MAC address.		Identifying the device is trivial if it has a unique MAC address.
	Once this unique MAC address is established, detecting any elements		Once this unique MAC address is established, detecting any elements
	that directly or indirectly identify the user of the device		that directly or indirectly identify the user of the device (i.e.,
	(Personally Identifiable Information, or PII) is enough to link the		Personally Identifiable Information (PII)) is enough to link the MAC
	MAC address to that user. Then, any detection of traffic that can be		address to that user. Then, any detection of traffic that can be
	associated with the device will also be linked to the known user of		associated with the device will also be linked to the known user of
	that device (Personally Correlated Information, or PCI).		that device (i.e., Personally Correlated Information (PCI)).
	2.1. Privacy of MAC Address		2.1. Privacy of MAC Addresses
	This possible identification or association presents a privacy issue,		The possible identification or association presents a privacy issue,
	especially with wireless technologies. For most of them, and in		especially with wireless technologies. For most of them
	particular for [IEEE_802.11], the source and destination MAC		([IEEE_802.11] in particular), the source and destination MAC
	addresses are not encrypted even in networks that implement		addresses are not encrypted, even in networks that implement
	encryption (so that each machine can easily detect if it is the		encryption. Thus, each machine can easily detect if it is the
	intended target of the message before attempting to decrypt its		intended target of the message before attempting to decrypt its
	content, and also identify the transmitter, to use the right		content, and also identify the transmitter, to use the right
	decryption key when multiple unicast keys are in effect).		decryption key when multiple unicast keys are in effect.
	This identification of the user associated with a node was clearly		This identification of the user associated with a node was clearly
	not the intent of the 802 MAC address. A logical solution to remove		not the intent of the IEEE 802 MAC address. A logical solution to
	this association is to use a locally administered address instead and		remove this association is to use a locally administered address
	change the address in a fashion that prevents a continuous		instead and change the address in a fashion that prevents a
	association between one MAC address and some PII. However, other		continuous association between one MAC address and some PII.
	network devices on the same LAN implementing a MAC layer also expect		However, other network devices on the same LAN implementing a MAC
	each device to be associated with a MAC address that would persist		layer also expect each device to be associated with a MAC address
	over time. When a device changes its MAC address, other devices on		that would persist over time. When a device changes its MAC address,
	the same LAN may fail to recognize that the same machine is		other devices on the same LAN may fail to recognize that the same
	attempting to communicate with them. This type of MAC addresses is		machine is attempting to communicate with them. This type of MAC
	referred to as 'persistent' MAC address in this document. This		address is referred to as 'persistent' MAC address in this document.
	assumption sometimes adds to the PII confusion, for example in the		This assumption sometimes adds to the PII confusion, for example, in
	case of Authentication, Authorization, and Accounting (AAA) services		the case of Authentication, Authorization, and Accounting (AAA)
	[RFC3539] authenticating the user of a machine and associating the		services [RFC3539] authenticating the user of a machine and
	authenticated user to the device MAC address. Other services solely		associating the authenticated user to the device MAC address. Other
	focus on the machine (e.g., DHCPv4 [RFC2131]), but still expect each		services solely focus on the machine (e.g., DHCPv4 [RFC2131]) but
	device to use a persistent MAC address, for example to re-assign the		still expect each device to use a persistent MAC address, for
	same IP address to a returning device. Changing the MAC address may		example, to reassign the same IP address to a returning device.
	disrupt these services.		Changing the MAC address may disrupt these services.
	3. The Actors: Network Functional Entities and Human Entities		3. The Actors: Network Functional Entities and Human Entities
	The risk of service disruption is weighed against the privacy		The risk of service disruption is weighed against the privacy
	benefits. However, the plurality of actors involved in the exchanges		benefits. However, the plurality of actors involved in the exchanges
	tends to blur the boundaries of what privacy violations should be		tends to blur the boundaries of which privacy violations should be
	protected against. It is therefore useful to list the actors		protected against. Therefore, it is useful to list the actors
	associated with the network exchanges, either because they actively		associated with the network exchanges because they either actively
	participate in these exchanges, or because they can observe them.		participate in these exchanges or can observe them. Some actors are
	Some actors are functional entities, while some others are human (or		functional entities, while others are human (or related) entities.
	related) entities.
	3.1. Network Functional Entities		3.1. Network Functional Entities
	Network communications based on IEEE 802 technologies commonly rely		Network communications based on IEEE 802 technologies commonly rely
	on station identifiers based on a MAC address. This MAC address is		on station identifiers based on a MAC address. This MAC address is
	utilized by several types of network functional entities such as		utilized by several types of network functional entities such as
	applications or devices that provide a service related to network		applications or devices that provide a service related to network
	operations.		operations.
	1. Wireless access network infrastructure devices (e.g., WLAN access		1. Wireless access network infrastructure devices (e.g., WLAN access
	points or controllers): these devices participate in IEEE 802 LAN		points or controllers): These devices participate in IEEE 802 LAN
	operations. As such, they need to identify each machine as a		operations. As such, they need to identify each machine as a
	source or destination to successfully continue exchanging frames.		source or destination to successfully continue exchanging frames.
	As a device changes its network attachment (roams) from one		As a device changes its network attachment (roams) from one
	access point to another, the access points can exchange		access point to another, the access points can exchange
	contextual information, (e.g., device MAC, keying material),		contextual information (e.g., device MAC and keying material),
	allowing the device session to continue seamlessly. These access		allowing the device session to continue seamlessly. These access
	points can also inform devices further in the wired network about		points can also inform devices further in the wired network about
	the roam to ensure that layer-2 frames are redirected to the new		the roam to ensure that Layer 2 frames are redirected to the new
	device access point.		device access point.
	2. Other network devices operating at the MAC layer: many wireless		2. Other network devices operating at the MAC layer: Many wireless
	network access devices (e.g., [IEEE_802.11] access points) are		network access devices (e.g., access points [IEEE_802.11]) are
	conceived as layer-2 devices, and as such, they bridge a frame		conceived as Layer 2 devices, and as such, they bridge a frame
	from one medium (e.g., [IEEE_802.11] or Wi-Fi) to another (e.g.,		from one medium (e.g., Wi-Fi [IEEE_802.11]) to another (e.g.,
	[IEEE_802.3] or Ethernet). This means that a wireless device MAC		Ethernet [IEEE_802.3]). This means that the MAC address of a
	address often exists on the wire beyond the wireless access		wireless device often exists on the wire beyond the wireless
	device. Devices connected to this wire also implement		access device. Devices connected to this wire also implement
	[IEEE_802.3] technologies and, as such, operate on the		IEEE 802.3 technologies [IEEE_802.3], and as such, they operate
	expectation that each device is associated with a MAC address		on the expectation that each device is associated with a MAC
	that persists for the duration of continuous exchanges. For		address that persists for the duration of continuous exchanges.
	example, switches and bridges associate MAC addresses to		For example, switches and bridges associate MAC addresses to
	individual ports (so as to know to which port to send a frame		individual ports (so as to know to which port to send a frame
	intended for a particular MAC address). Similarly, AAA services		intended for a particular MAC address). Similarly, AAA services
	can validate the identity of a device and use the device's MAC		can validate the identity of a device and use the device's MAC
	address as a first pointer to the device identity (before		address as the first pointer to the device identity (before
	operating further verification). Similarly, some networking		operating further verification). Similarly, some networking
	devices offer layer-2 filtering policies that may rely on the		devices offer Layer 2 filtering policies that may rely on the
	connected MAC addresses. 802.1X-enabled [IEEE_802.1X] devices may		connected MAC addresses. IEEE 802.1X-enabled devices
	also selectively put the interface in a blocking state until a		[IEEE_802.1X] may also selectively put the interface in a
	connecting device is authenticated. These services then use the		blocking state until a connecting device is authenticated. These
	MAC address as a first pointer to the device identity to allow or		services then use the MAC address as the first pointer to the
	block data traffic. This list is not exhaustive. Multiple		device identity to allow or block data traffic. This list is not
	services are defined for [IEEE_802.3] networks, and multiple		exhaustive. Multiple services are defined for IEEE 802.3
	services defined by the IEEE 802.1 working group are also		networks [IEEE_802.3], and multiple services defined by the IEEE
	applicable to [IEEE_802.3] networks. Wireless access points may		802.1 Working Group are also applicable to IEEE 802.3 networks
	also connect to other mediums than [IEEE_802.3] (e.g., DOCSIS		[IEEE_802.3]. Wireless access points may also connect to mediums
			other than [IEEE_802.3] (e.g., the Data-Over-Cable Service
	[DOCSIS]), which also implements mechanisms under the umbrella of		Interface Specification (DOCSIS) [DOCSIS]), which also implements
	the general 802 Standard, and therefore expect the unique and		mechanisms under the umbrella of the general IEEE 802 standard
	persistent association of a MAC address to a device.		and therefore expect the unique and persistent association of a
			MAC address to a device.
	3. Network devices operating at upper layers: some network devices		3. Network devices operating at upper layers: Some network devices
	provide functions and services above the MAC layer. Some of them		provide functions and services above the MAC layer. Some of them
	also operate a MAC layer function: for example, routers provide		also operate a MAC layer function. For example, routers provide
	IP forwarding services but rely on the device MAC address to		IP forwarding services but rely on the device MAC address to
	create the appropriate frame structure. Other devices and		create the appropriate frame structure. Other devices and
	services operate at upper layers but also rely upon the 802		services operate at upper layers but also rely upon the IEEE 802
	principles of unique MAC-to-device mapping. For example, Address		principles of unique MAC-to-device mapping. For example, the
	Resolution Protocol (ARP) [RFC826] and Neighbor Discovery		Address Resolution Protocol (ARP) [RFC826] and Neighbor Discovery
	Protocol (NDP) [RFC4861] use MAC address to create the mapping of		Protocol (NDP) [RFC4861] use a MAC address to create the mapping
	an IP address to a MAC address for packet forwarding. If a		of an IP address to a MAC address for packet forwarding. If a
	device changes its MAC address without a mechanism to notify the		device changes its MAC address without a mechanism to notify the
	layer-2 switch it is connected to or the provider of a service		Layer 2 switch it is connected to or is the provider of a service
	that expects a stable MAC-to-device mapping, the provider of the		that expects a stable MAC-to-device mapping, the provider of the
	service and traffic forwarding may be disrupted.		service and traffic forwarding may be disrupted.
	3.2. Human-related Entities		3.2. Human-Related Entities
	Humans may actively participate in the network structure and		Humans may actively participate in the network structure and
	operations, or be observers at any point of the network lifecycle.		operations or be observers at any point of the network lifecycle.
	Humans could be wireless device users or people operating wireless		Humans could be users of wireless devices or people operating
	networks.		wireless networks.
	1. Over-The-Air (OTA) observers: as the transmitting or receiving		1. Over-the-Air (OTA) observers: The transmitting or receiving MAC
	MAC address is usually not encrypted in wireless 802-technologies		address is usually not encrypted in wireless exchanges in IEEE
	exchanges, and as any protocol-compatible device in range of the		802 technologies, and any protocol-compatible device in range of
	signal can read the frame header. As such OTA observers are able		the signal can read the frame header. As such, OTA observers are
	to read the MAC addresses of individual transmissions. Some		able to read the MAC addresses of individual transmissions. Some
	wireless technologies also support techniques to establish		wireless technologies also support techniques to establish
	distances or positions, allowing the observer, in some cases, to		distances or positions, allowing the observer, in some cases, to
	uniquely associate the MAC address with a physical device and its		uniquely associate the MAC address with a physical device and its
	associated location. An OTA observer may have a legitimate		associated location. An OTA observer may have a legitimate
	reason to monitor a particular device, for example, for IT		reason to monitor a particular device, for example, for IT
	support operations. However, another actor might also monitor		support operations. However, another actor might also monitor
	the same device to obtain PII or PCI.		the same device to obtain PII or PCI.
	2. Wireless access network operators: some wireless access networks		2. Wireless access network operators: Some wireless access networks
	host devices that meet specific requirements, such as device type		host devices that meet specific requirements, such as device type
	(e.g., IoT-only networks, factory operational networks).		(e.g., IoT-only networks and factory operational networks).
	Therefore, operators can attempt to identify the devices (or the		Therefore, operators can attempt to identify the devices (or the
	users) connecting to the networks under their care. They often		users) connecting to the networks under their care. They often
	use the MAC address to represent an identified device.		use the MAC address to represent an identified device.
	3. Network access providers: wireless access networks are often		3. Network access providers: Wireless access networks are often
	considered beyond the first 2 layers of the OSI model. For		considered beyond the first two layers of the OSI model. For
	example, law enforcement agency (e.g., FBI in the United States)		example, a law enforcement agency (e.g., the FBI in the United
	may legally require the network access provider to identify		States) may legally require the network access provider to
	communications from a subject. In this context, the operating		identify communications from a subject. In this context, the
	access networks need to identify the devices used by the subjects		operating access networks need to identify the devices used by
	and cross-reference the data generated by the devices in the		the subjects and cross-reference the data generated by the
	network. In other contexts, the operating access networks assign		devices in the network. In other contexts, the operating access
	resources based on contractual conditions (e.g., fee, bandwidth		networks assign resources based on contractual conditions (e.g.,
	fair share). In these scenarios, the operators may use the MAC		fee and bandwidth fair share). In these scenarios, the operators
	address to identify the devices and the users of their networks.		may use the MAC address to identify the devices and the users of
			their networks.
	4. Over-The-Wired internal (OTWi) observers: because the device		4. Over-the-Wired internal (OTWi) observers: Because the device
	wireless MAC address continues to be present over the wire if the		wireless MAC address continues to be present over the wire if the
	infrastructure connection device (e.g., access point) functions		infrastructure connection device (e.g., access point) functions
	as a layer-2 bridge, observers may be positioned over the wire		as a Layer 2 bridge, observers may be positioned over the wire
	and read transmission MAC addresses. Such capability supposes		and may read transmission MAC addresses. Such capability
	that the observer has access to the wired segment of the		supposes that the observer has access to the wired segment of the
	broadcast domain where the frames are exchanged. A broadcast		broadcast domain where the frames are exchanged. A broadcast
	domain is a logical segment of a network in which devices can		domain is a logical segment of a network in which devices can
	send, receive, and monitor data frames from all other devices		send, receive, and monitor data frames from all other devices
	within the same segment. In most networks, such capability		within the same segment. In most networks, such capability
	requires physical access to an infrastructure wired device in the		requires physical access to an infrastructure wired device in the
	broadcast domain (e.g., switch closet), and is therefore not		broadcast domain (e.g., switch closet) and is therefore not
	accessible to all.		accessible to all.
	5. Over-The-Wired external (OTWe) observers: beyond the broadcast		5. Over-the-Wired external (OTWe) observers: Beyond the broadcast
	domain, frame headers are removed by a routing device, and a new		domain, frame headers are removed by a routing device, and a new
	layer-2 header is added before the frame is transmitted to the		Layer 2 header is added before the frame is transmitted to the
	next segment. The device MAC address is not visible anymore		next segment. The device MAC address is not visible anymore
	unless a mechanism copies the MAC address into a field that can		unless a mechanism copies the MAC address into a field that can
	be read while the packet travels onto the next segment (e.g.,		be read while the packet travels to the next segment (e.g., IPv6
	pre- [RFC4941] and pre-[RFC7217] IPv6 addresses built from the		addresses built from the MAC address prior to the use of the
	MAC address). Therefore, unless this last condition exists, OTWe		methods defined in [RFC4941] and [RFC7217]). Therefore, unless
	observers are not able to see the device's MAC address.		this last condition exists, OTWe observers are not able to see
			the device's MAC address.
	4. Degrees of Trust		4. Degrees of Trust
	The surface of PII exposures that can drive MAC address randomization		The surface of PII exposures that can drive MAC address randomization
	depends on (1) the environment where the device operates, (2) the		depends on (1) the environment where the device operates, (2) the
	presence and nature of other devices in the environment, and (3) the		presence and nature of other devices in the environment, and (3) the
	type of network the device is communicating through. Consequently, a		type of network the device is communicating through. Consequently, a
	device can use an identifier (such as a MAC address) that can persist		device can use an identifier (such as a MAC address) that can persist
	over time if trust with the environment is established, or that can		over time if trust with the environment is established, or it can use
	be temporary if an identifier is required for a service in an		an identifier that is temporary if an identifier is required for a
	environment where trust has not been established. Note that trust is		service in an environment where trust has not been established. Note
	not binary. It is useful to distinguish what trust a personal device		that trust is not binary. It is useful to distinguish what trust a
	may establish with the different entities at play in a network domain		personal device may establish with the different entities at play in
	where a MAC address may be visible:		a network domain where a MAC address may be visible:
	1. Full trust: there is environment where a device establishes a		1. Full trust: There is an environment where a device establishes a
	trust relationship, and the device can share its persistent MAC		trust relationship, and the device can share its persistent MAC
	address with the access network devices (e.g., access point and		address with the access network devices (e.g., access point and
	WLAN Controller). In this environment, the network provides		WLAN controller). The network provides necessary security
	necessary security measures to prevent observers or network		measures to prevent observers or network actors from accessing
	actors from accessing PII. The device (or its user) also has		PII. The device (or its user) also has confidence that its MAC
	confidence that its MAC address is not shared beyond the layer-2		address is not shared beyond the Layer 2 broadcast domain
	broadcast domain boundary.		boundary.
	2. Selective trust: in another environment, depending on the pre-		2. Selective trust: In another environment, depending on the
	defined privacy policies, a device may decide to use one pseudo-		predefined privacy policies, a device may decide to use one
	persistent MAC address for a set of network elements and another		pseudo-persistent MAC address for a set of network elements and
	pseudo-persistent MAC address for another set of network		another pseudo-persistent MAC address for another set of network
	elements. Examples of privacy policies can be SSID and BSSID		elements. Examples of privacy policies can be a combination of
	combination, a particular time-of-day, or a pre-set time		Service Set Identifier (SSID) and Basic Service Set Identifier
	duration.		(BSSID), a particular time of day, or a preset time duration.
	3. Zero trust: in another environment, a device may randomize its		3. Zero trust: In another environment, a device may randomize its
	MAC address with any local entity reachable through the AP. It		MAC address with any local entity reachable through the AP. It
	may generate a temporary MAC address to each of them. That		may generate a temporary MAC address to each of them. That
	temporary MAC address may or may not be the same for different		temporary MAC address may or may not be the same for different
	services.		services.
	5. Environment		5. Environments
	The trust relationship depends on the relationship between the user		The trust relationship depends on the relationship between the user
	of a personal device and the operator of a network service that the		of a personal device and the operator of a network service that the
	personal device may use. It is useful to observe the typical trust		personal device may use. It is useful to observe the typical trust
	structure of common environments:		structure of common environments:
	A. Residential settings under the control of the user: this is a		(A) Residential settings under the control of the user: This is a
	typical home network with Wi-Fi in the LAN and Internet in the		typical home network with Wi-Fi in the LAN and Internet in the
	WAN. In this environment, traffic over the Internet does not		WAN. In this environment, traffic over the Internet does not
	expose the MAC address of the internal device if it is not copied		expose the MAC address of the internal device if it is not
	to another field before routing happens. The wire segment within		copied to another field before routing happens. The wire
	the broadcast domain is under the control of the user and is		segment within the broadcast domain is under the control of the
	usually not at risk of hosting an eavesdropper. Full trust is		user and is usually not at risk of hosting an eavesdropper.
	typically established at this level among users and with the		Full trust is typically established at this level among users
	network elements. Note that Full trust in this context is		and with the network elements. Note that "Full trust" in this
	referring to the MAC address persistency. It does not extend to		context is referring to the MAC address persistency. It does
	full trust between applications or devices. The device trusts		not extend to full trust between applications or devices. The
	the access point and all layer-2 domain entities beyond the		device trusts the access point and all Layer 2 domain entities
	access point, where the Wi-Fi transmissions can be detected,		beyond the access point, where the Wi-Fi transmissions can be
	there is no guarantee that an eavesdropper will not observe the		detected, but there is no guarantee that an eavesdropper will
	communications. As such, it is common to assume that, even in		not observe the communications. As such, even in this
	this environment, attackers may still be able to monitor the		environment, it is common to assume that attackers may still be
	unencrypted information such as MAC addresses. If a device		able to monitor unencrypted information such as MAC addresses.
	decided to not fully trust the network, it might apply any		If a device decides to not fully trust the network, it might
	necessary policy to protect its identity. Most devices in the		apply any necessary policy to protect its identity. Most
	network only require simple connectivity so that the network		devices in the network only require simple connectivity so that
	services are simple. For network support, it is also simple. It		the network services are simple. For network support, it is
	is usually related to Internet connectivity.		also simple. It is usually related to Internet connectivity.
	B. Managed residential settings: examples of this type of		(B) Managed residential settings: Examples of this type of
	environments include shared living facilities and other		environment include shared living facilities and other
	collective environments where an operator manages the network for		collective environments where an operator manages the network
	the residents. The OTA exposure is similar to (A). The operator		for the residents. The OTA exposure is similar to (A). The
	may be requested to provide IT support to the residents and may		operator may be requested to provide IT support to the residents
	need to identify a device activity in real-time. It may also		and may need to identify device activity in real time or analyze
	need to analyze logs. The infrastructure is shared and covers a		logs. The infrastructure is shared and covers a larger area
	larger area than (A), residents may connect to the network from		than in (A); residents may connect to the network from different
	different locations. For example, they may regularly connect to		locations. For example, they may regularly connect to the
	the network from their own apartments. They may occasionally		network from their own apartments and occasionally connect from
	connect to the network from common areas. The device may decide		common areas. The device may decide to use different pseudo-
	to use different pseudo-persistent MAC address as we described in		persistent MAC addresses as described in Section 4. As such,
	Section 4. As such, the trust degree is Selective trust. In		the degree of trust is "Selective trust". In this environment,
	this environment, the network services will be slightly more		the network services will be slightly more complex than in (A).
	complex than (A). Network may be segmented by locations and		The network may be segmented by locations and multiple SSIDs.
	multiple SSID. User's devices should be able to join the network		Users' devices should be able to join the network without pre-
	without pre-certification and pre-approval. In most cases, users		certification or pre-approval. In most cases, users only need
	only need simple connectivity; thus, network support will be		simple connectivity; thus, network support will be slightly (but
	slightly but not significantly more complicated than (A).		not significantly) more complicated than in (A).
	C. Public guest networks: public hotspots in shopping malls, hotels,		(C) Public guest networks: Public hotspots in shopping malls,
	stores, train stations, and airports are typical examples of this		hotels, stores, train stations, and airports are typical
	environment. In this environment, trust is commonly not		examples of this environment. In this environment, trust is
	established with any element of the layer-2 broadcast domain.		commonly not established with any element of the Layer 2
	Users do not anticipate a public guest network using the MAC		broadcast domain. Users do not anticipate a public guest
	address information to identify their location and network		network using the MAC address information to identify their
	activity. They do not trust the network and do not want the		location and network activity. They do not trust the network
	network to memorize them permanently. The trust degree is Zero.		and do not want the network to memorize them permanently. The
	Devices in this network should avoid using long-lived MAC address		degree of trust is "Zero trust". Devices in this network should
	to prevent fingerprinting. For example, the device may use a		avoid using a long-lived MAC address to prevent fingerprinting.
	different MAC address every time it attaches to a new Wi-Fi		For example, the device may use a different MAC address every
	access point. Some guest network operators may legally abide to		time it attaches to a new Wi-Fi access point. Some guest
	identify devices. They should not use the MAC address for such		network operators may legally abide to identify devices. They
	function. Most users connecting to public guest network only		should not use the MAC address for such a function. Most users
	expect simple Internet connectivity services, so the network		connecting to a public guest network only expect simple Internet
	services are simple. If users have issue to connect to the		connectivity services, so the network services are simple. If
	network or to access the Internet, they expect limited to no		users have issues connecting to the network or accessing the
	technical support. Thus, the network support level is low.		Internet, they expect limited to no technical support. Thus,
			the network support level is low.
	D. Enterprises with Bring-Your-Own-Device (BYOD): this type of		(D) Enterprises with Bring-Your-Own-Device (BYOD): This type of
	networks are similar to (B) except that the onboarding devices		network is similar to (B) except that the onboarding devices are
	are subjected to pre-approval and pre-certification. The devices		subjected to pre-approval and pre-certification. The devices
	are usually personal devices and are not under the control of the		are usually personal devices and are not under the control of
	corporate IT team. Compared to residential network, enterprise		the corporate IT team. Compared to residential networks,
	network usually provides more sophisticated network services		enterprise networks usually provide more sophisticated network
	including but not limited to application-based network policies		services including, but not limited to, application-based and
	and identity-based network policies. Change of MAC address may		identity-based network policies. Changing the MAC address may
	interrupt network services if the services are based on MAC		interrupt network services if the services are based on that MAC
	address. Thus, network operations will be more complex, so the		address. Thus, network operations will be more complex, so the
	network support level is high.		network support level is high.
	E. Managed enterprises: in this environment: this type of networks		(E) Managed enterprises: This type of network is similar to (C).
	are similar to (C). The main difference is the devices are owned		The main difference is that the devices are owned and managed by
	and managed by the enterprise. Given the network and the devices		the enterprise. Because both the network and the devices are
	are owned and managed by the enterprise, the trust degree is Full		owned and managed by the enterprise, the degree of trust is
	trust. Network services and network support level are same as		"Full trust". Network services and the network support level
	(D)		are the same as in (D).
	Table 1 summarizes the environment in a table format.		Table 1 summarizes the environments described above.
	+=======================+===========+=======+========+=============+		+=======================+===========+=======+========+=============+
	| Use Cases | Trust |Network|Network | Network |		| Use Cases | Degree of |Network|Network | Network |
	| | Degree | Admin |Services| Support |		| | Trust |Admin |Services| Support |
	| | | | | Expectation |		| | | | | Expectation |
	+=======================+===========+=======+========+=============+		+=======================+===========+=======+========+=============+
	| (A) Residential | Full | User | Simple | Low |		| (A) Residential | Full |User |Simple | Low |
	| settings under the | trust | | | |		| settings under the | trust | | | |
	| control of the user | | | | |		| control of the user | | | | |
	+-----------------------+-----------+-------+--------+-------------+		+-----------------------+-----------+-------+--------+-------------+
	| (B) Managed | Selective | IT | Medium | Medium |		| (B) Managed | Selective |IT |Medium | Medium |
	| residential settings | trust | | | |		| residential settings | trust | | | |
	+-----------------------+-----------+-------+--------+-------------+		+-----------------------+-----------+-------+--------+-------------+
	| (C) Public guest | Zero | ISP | Simple | Low |		| (C) Public guest | Zero |ISP |Simple | Low |
	| networks | trust | | | |		| networks | trust | | | |
	+-----------------------+-----------+-------+--------+-------------+		+-----------------------+-----------+-------+--------+-------------+
	| (D) Enterprises with | Selective | IT |Complex | High |		| (D) Enterprises with | Selective |IT |Complex | High |
	| Bring-Your-Own-Device | trust | | | |		| Bring-Your-Own-Device | trust | | | |
	| (BYOD) | | | | |		| (BYOD) | | | | |
	+-----------------------+-----------+-------+--------+-------------+		+-----------------------+-----------+-------+--------+-------------+
	| (E) Managed | Full | IT |Complex | High |		| (E) Managed | Full |IT |Complex | High |
	| enterprises | trust | | | |		| enterprises | trust | | | |
	+-----------------------+-----------+-------+--------+-------------+		+-----------------------+-----------+-------+--------+-------------+
	Table 1: Use Cases		Table 1: Use Cases
	Existing technical frameworks that address some of the requirements		Existing technical frameworks that address some of the requirements
	of the use cases listed above in Appendix A.		of the use cases listed above are discussed in Appendix A.
	6. Network Services		6. Network Services
	Different network environments provide different levels of network		Different network environments provide different levels of network
	services, from simple to complex. At its simplest level, a network		services, from simple to complex. At its simplest level, a network
	can provide a wireless connecting device basic IP communication		can provide a wireless connecting device with basic IP communication
	service (e.g., DHCPv4 [RFC2131] or SLAAC [RFC4862]) and an ability to		service (e.g., DHCPv4 [RFC2131] or Stateless Address
	connect to the Internet (e.g., DNS service or relay, and routing in		Autoconfiguration (SLAAC) [RFC4862]) and an ability to connect to the
	and out through a local gateway). The network can also offer more		Internet (e.g., DNS service or relay and routing in and out through a
	advanced services, such as managed instant messaging service, file		local gateway). The network can also offer more advanced services,
	storage, printing, and/or local web service. Larger and more complex		such as managed instant messaging service, file storage, printing,
	networks can also incorporate more advanced services, from AAA to AR/		and/or local web service. Larger and more complex networks can also
	VR applications. To the network, its top priority is to provide the		incorporate more advanced services, from AAA to AR/VR applications.
	best Quality of Experience to its users. Often the network contains		To the network, its top priority is to provide the best quality of
	policies which help to make forwarding decision based on the network		experience to its users. Often the network contains policies that
	conditions, the device, and the user identity associated to the		help to make a forwarding decision based on the network conditions,
	device. For example, in a hospital private network, the network may		the device, and the user identity associated to the device. For
	contain policy to give highest priority to doctors' Voice-Over-IP		example, in a hospital private network, the network may contain a
	packets. In another example, an enterprise network may contain		policy to give highest priority to doctors' Voice-Over-IP packets.
	policy to allow applications from a group of authenticated devices to		In another example, an enterprise network may contain a policy to
	use ECN [RFC3168] for congestion and/or DSCP [RFC8837] for		allow applications from a group of authenticated devices to use
	classification to signal the network for specific network policy. In		Explicit Congestion Notification (ECN) [RFC3168] for congestion and/
	this configuration, the network is required to associate the data		or Differentiated Services Code Point (DSCP) [RFC8837] for
			classification to signal the network for a specific network policy.
			In this configuration, the network is required to associate the data
	packets to an identity to validate the legitimacy of the marking.		packets to an identity to validate the legitimacy of the marking.
	Before RCM, many network systems use MAC address as a persistent		Before RCM, many network systems used a MAC address as a persistent
	identity to create an association between user and device. After RCM		identity to create an association between user and device. After
	being implemented, the association is broken.		implementing RCM, the association is broken.
	6.1. Device Identification and Associated Problems		6.1. Device Identification and Associated Problems
	Wireless access points and controllers use the MAC address to		Wireless access points and controllers use the MAC address to
	validate the device connection context, including protocol		validate the device connection context, including protocol
	capabilities, confirmation that authentication was completed, Quality		capabilities, confirmation that authentication was completed, quality
	of Service or security profiles, and encryption keying material.		of service or security profiles, and encryption keying material.
	Some advanced access points and controllers also include upper layer		Some advanced access points and controllers also include upper layer
	functions whose purpose is covered below. A device changing its MAC		functions whose purpose is covered below. A device changing its MAC
	address, without another recorded device identity, would cause the		address, without another recorded device identity, would cause the
	access point and the controller to lose the relation between a		access point and the controller to lose the relation between a
	connection context and the corresponding device. As such, the		connection context and the corresponding device. As such, the Layer
	layer-2 infrastructure does not know that the device (with its new		2 infrastructure does not know that the device (with its new MAC
	MAC address) is authorized to communicate through the network. The		address) is authorized to communicate through the network. The
	encryption keying material is not identified anymore (causing the		encryption keying material is not identified anymore (causing the
	access point to fail to decrypt the device packets and fail to select		access point to fail to decrypt the device packets and fail to select
	the right key to send encrypted packets to the device). In short,		the right key to send encrypted packets to the device). In short,
	the entire context needs to be rebuilt, and a new session restarted.		the entire context needs to be rebuilt, and a new session restarted.
	The time consumed by this procedure breaks any flow that needs		The time consumed by this procedure breaks any flow that needs
	continuity or short delay between packets on the device (e.g., real-		continuity or short delay between packets on the device (e.g., real-
	time audio, video, AR/VR, etc.). For example: [IEEE_802.11i]		time audio, video, AR/VR, etc.). For example, [IEEE_802.11i]
	recognizes that a device may leave and re-join the network after a		recognizes that a device may leave and rejoin the network after a
	short time window. As such, the standard suggests that the		short time window. As such, the standard suggests that the
	infrastructure should keep the context for a device for a while after		infrastructure should keep the context for a device for a while after
	the device was last seen. The device should maintain the same MAC		the device was last seen. The device should maintain the same MAC
	address in such scenario.		address in such a scenario.
	Some network equipment such as Multi-Layer routers and Wi-Fi Access		Some network equipment such as multi-layer routers and Wi-Fi access
	Points which serve both layer-2 and layer-3 in the same device rely		points, which serve both Layer 2 and Layer 3 in the same device, rely
	on ARP [RFC826], and NDP [RFC4861], to build the MAC-to-IP table for		on ARP [RFC826] and NDP [RFC4861] to build the MAC-to-IP table for
	packet forwarding. The size of the MAC address cache in the layer-2		packet forwarding. The size of the MAC address cache in the Layer 2
	switch is finite. If new entries are created faster than the old		switch is finite. If new entries are created faster than the old
	entries flushed by the idle timer, it is possible to cause		entries are flushed by the idle timer, it is possible to cause an
	unintentional deny-of-service attack. For example, default timeout		unintentional denial-of-service attack. For example, the default
	of MAC address cache in Linux is set to 300s. Aggressive MAC		timeout of the MAC address cache in Linux is set to 300 seconds.
	randomization from many devices in a short time interval (e.g., less		Aggressive MAC randomization from many devices in a short time
	than 300s) may cause the layer-2 switch to exhaust its resources,		interval (e.g., less than 300 seconds) may cause the Layer 2 switch
	holding in memory traffic for a device whose entry can no longer be		to exhaust its resources, holding in memory traffic for a device
	found. For the RCM device, these effects translate into session		whose entry can no longer be found. For the RCM device, these
	discontinuity and disrupt the active sessions. The discontinuity		effects translate into session discontinuity and disrupt the active
	impact may vary. Real-time applications such as video conference may		sessions. The discontinuity impact may vary. Real-time applications
	experience short interruption while non-real-time applications such		such as video conference may experience short interruption while non-
	as video streaming may experience minimal or no impact. The device		real-time applications such as video streaming may experience minimal
	should carefully balance when to change the MAC address after		or no impact. The device should carefully balance when to change the
	analyzing the nature of the running applications and its privacy		MAC address after analyzing the nature of the running applications
	policy.		and its privacy policy.
	In wireless contexts, [IEEE_802.1X] authenticators rely on the device		In wireless contexts, IEEE 802.1X authenticators [IEEE_802.1X] rely
	and user identity validation provided by an AAA server to change the		on the device and user identity validation provided by a AAA server
	interface from a blocking state to a forwarding state. The MAC		to change the interface from a blocking state to a forwarding state.
	address is used to verify that the device is in the authorized list,		The MAC address is used to verify that the device is in the
	and to retrieve the associated key used to decrypt the device		authorized list and to retrieve the associated key used to decrypt
	traffic. A change in MAC address causes the port to be closed to the		the device traffic. A change in MAC address causes the port to be
	device data traffic until the AAA server confirms the validity of the		closed to the device data traffic until the AAA server confirms the
	new MAC address. Consequently, MAC address randomization can disrupt		validity of the new MAC address. Consequently, MAC address
	the device traffic and strain the AAA server.		randomization can disrupt the device traffic and strain the AAA
			server.
	DHCPv4 servers [RFC2131], without a unique identification of the		Without a unique identification of the device, DHCPv4 servers
	device, lose track of which IP address is validly assigned. Unless		[RFC2131] lose track of which IP address is validly assigned. Unless
	the RCM device releases the IP address before changing its MAC		the RCM device releases the IP address before changing its MAC
	address, DHCPv4 servers are at risk of scope exhaustion, causing new		address, DHCPv4 servers are at risk of scope exhaustion, causing new
	devices (and RCM devices) to fail to obtain a new IP address. Even		devices (and RCM devices) to fail to obtain a new IP address. Even
	if the RCM device releases the IP address before changing the MAC		if the RCM device releases the IP address before changing the MAC
	address, the DHCPv4 server typically holds the released IP address		address, the DHCPv4 server typically holds the released IP address
	for a certain duration, in case the leaving MAC returns. As the		for a certain duration, in case the leaving MAC returns. As the
	DHCPv4 [RFC2131] server cannot know if the release is due to a		DHCPv4 server [RFC2131] cannot know if the release is due to a
	temporary disconnection or a MAC randomization, the risk of scope		temporary disconnection or a MAC randomization, the risk of scope
	address exhaustion exists even in cases where the IP address is		address exhaustion exists even in cases where the IP address is
	released.		released.
	Network devices with self-assigned IPv6 addresses (e.g., with SLAAC		Network devices with self-assigned IPv6 addresses (e.g., with SLAAC
	defined in [RFC4862]) and devices using static IP addresses rely on		[RFC4862]) and devices using static IP addresses rely on mechanisms
	mechanisms like Optimistic Duplicate Address Detection (DAD)		like Optimistic Duplicate Address Detection (DAD) [RFC4429] and NDP
	[RFC4429] and NDP [RFC4861] for peer devices to establish the		[RFC4861] for peer devices to establish the association between the
	association between the target IP address and a MAC address, and		target IP address and a MAC address, and these peers may cache this
	these peers may cache this association in memory. Changing the MAC		association in memory. Changing the MAC address, even at the
	address, even at disconnection-reconnection phase, without changing		disconnection-reconnection phase, without changing the IP address may
	the IP address, may disrupt the stability of these mappings for these		disrupt the stability of these mappings for these peers if the change
	peers, if the change occurs within the caching period. Note that		occurs within the caching period. Note that this behavior is against
	this behavior is against standard operation and existing privacy		standard operation and existing privacy recommendations.
	recommendations. Implementations must avoid changing MAC address		Implementations must avoid changing the MAC address while maintaining
	while maintaining previously assigned IP address without consulting		the previously assigned IP address without consulting the network.
	the network.
	Routers keep track of which MAC address is on which interface, so		Routers keep track of which MAC address is on which interface so that
	they can form the proper Data Link header when forwarding a packet to		they can form the proper Data Link header when forwarding a packet to
	a segment where MAC addresses are used. MAC address randomization		a segment where MAC addresses are used. MAC address randomization
	can cause MAC address cache exhaustion, but also the need for		can cause MAC address cache exhaustion but also the need for frequent
	frequent Address Resolution Protocol (ARP), Reverse Address		Address Resolution Protocol (ARP), Reverse Address Resolution
	Resolution Protocol (RARP) [RFC826], Neighbor Solicitation and,		Protocol (RARP) [RFC826], and Neighbor Solicitation and Neighbor
	Neighbor Advertisement [RFC4861] exchanges.		Advertisement [RFC4861] exchanges.
	In residential settings (environment type A in Section 5), policies		In residential settings (environment type A in Section 5), policies
	can be in place to control the traffic of some devices (e.g.,		can be in place to control the traffic of some devices (e.g.,
	parental control or block-list filters). These policies are often		parental control or blocklist filters). These policies are often
	based on the device's MAC address. MAC address randomization removes		based on the device's MAC address. MAC address randomization removes
	the possibility for such control.		the possibility for such control.
	In residential settings (environment type A) and in enterprises		In residential settings (environment type A) and in enterprises
	(environment types D and E), device recognition and ranging may be		(environment types D and E), device recognition and ranging may be
	used for IoT-related functionalities (door unlock, preferred light		used for IoT-related functionalities (e.g., door unlock, preferred
	and temperature configuration, etc.) These functions often rely on		light and temperature configuration, etc.) These functions often
	the detection of the device's wireless MAC address. MAC address		rely on the detection of the device's wireless MAC address. MAC
	randomization breaks the services based on such model.		address randomization breaks the services based on such models.
	In managed residential settings (environment types B) and in		In managed residential settings (environment type B) and in
	enterprises (environment types D and E), the network operator is		enterprises (environment types D and E), the network operator is
	often requested to provide IT support. With MAC address		often requested to provide IT support. With MAC address
	randomization, real-time support is only possible if the user can		randomization, real-time support is only possible if the user can
	provide the current MAC address. Service improvement support is not		provide the current MAC address. Service improvement support is not
	possible if the MAC address that the device had at the (past) time of		possible if the MAC address that the device had at the time of the
	the reported issue is not known at the time the issue is reported.		reported issue (in the past) is not known at the time the issue is
			reported.
	In industrial environments, policies are associated with each group		In industrial environments, policies are associated with each group
	of objects, including IoT devices. MAC address randomization may		of objects, including IoT devices. MAC address randomization may
	prevent an IoT device from being identified properly, thus leading to		prevent an IoT device from being identified properly and thus lead to
	network quarantine and disruption of operations.		network quarantine and disruption of operations.
	7. IANA Considerations		7. IANA Considerations
	This memo includes no request to IANA.		This document has no IANA actions.
	8. Security Considerations		8. Security Considerations
	Privacy considerations are discussed throughout this document.		Privacy considerations are discussed throughout this document.
	9. Informative References		9. Informative References
	[DOCSIS] "DOCSIS 4.0 Physical Layer Specification Version I06, DOI		[DOCSIS] CableLabs, "Cable Modem Operations Support System
	CM-SP-CM-OSSIv4.0", CableLabs DOCSIS , March 2022,		Interface Specification", Data-Over-Cable Service
	<https://www.cablelabs.com/specifications/CM-SP-CM-		Interface Specifications, DOCSIS 4.0, Version I06, March
			2022, <https://www.cablelabs.com/specifications/CM-SP-CM-
	OSSIv4.0?v=I06>.		OSSIv4.0?v=I06>.
	[I-D.ietf-radext-deprecating-radius]		[IEEE_802] IEEE, "IEEE Standard for Local and Metropolitan Area
	DeKok, A., "Deprecating Insecure Practices in RADIUS",		Networks: Overview and Architecture", IEEE Std 802-2014,
	Work in Progress, Internet-Draft, draft-ietf-radext-		DOI 10.1109/IEEESTD.2014.6847097, 30 June 2014,
	deprecating-radius-05, 26 November 2024,
	<https://datatracker.ietf.org/doc/html/draft-ietf-radext-
	deprecating-radius-05>.
	[I-D.tomas-openroaming]
	Tomas, B., Grayson, M., Canpolat, N., Cockrell, B., and S.
	Gundavelli, "WBA OpenRoaming Wireless Federation, Work in
	Progress, Internet-Draft, draft-tomas-openroaming-03", 25
	July 2024, <https://datatracker.ietf.org/doc/html/draft-
	tomas-openroaming-03>.
	[IEEE_802] "IEEE Std 802 - IEEE Standard for Local and Metropolitan
	Area Networks: Overview and Architecture, DOI 10.1109/
	IEEESTD.2014.6847097", IEEE 802 , 30 June 2014,
	<https://ieeexplore.ieee.org/document/6847097>.		<https://ieeexplore.ieee.org/document/6847097>.
	[IEEE_802.11]		[IEEE_802.11]
	"IEEE 802.11-2020 - Wireless LAN Medium Access Control		IEEE, "IEEE Standard for Information Technology--
			Telecommunications and Information Exchange between
			Systems - Local and Metropolitan Area Networks--Specific
			Requirements - Part 11: Wireless LAN Medium Access Control
	(MAC) and Physical Layer (PHY) Specifications", IEEE		(MAC) and Physical Layer (PHY) Specifications", IEEE
	802.11 , 11 February 2021,		Std 802.11-2020, DOI 10.1109/IEEESTD.2021.9363693, 26
	<https://standards.ieee.org/ieee/802.11/7028/>.		February 2021,
			<https://ieeexplore.ieee.org/document/9363693>.
	[IEEE_802.11bh]		[IEEE_802.11bh]
	"IEEE 802.11bh-2023 - Wireless LAN Medium Access Control		IEEE, "IEEE Draft Standard for Information Technology--
			Telecommunications and Information Exchange Between
			Systems Local and Metropolitan Area Networks--Specific
			Requirements - Part 11: Wireless LAN Medium Access Control
	(MAC) and Physical Layer (PHY) Specifications Amendment 8		(MAC) and Physical Layer (PHY) Specifications Amendment 8
	: Operation with Randomized and Changing MAC Addresses",		: Operation with Randomized and Changing MAC Addresses",
	IEEE 802.11bh , 19 July 2023,		IEEE P802.11bh/D1.0, 19 July 2023,
	<https://ieeexplore.ieee.org/document/10214483>.		<https://ieeexplore.ieee.org/document/10214483>.
	[IEEE_802.11i]		[IEEE_802.11i]
	"IEEE 802.11i-2004 - Wireless LAN Medium Access Control		IEEE, "IEEE 802.11i-2004 - Wireless LAN Medium Access
	(MAC) and Physical Layer (PHY) specifications: Amendment		Control (MAC) and Physical Layer (PHY) specifications:
	6: Medium Access Control (MAC) Security Enhancements, DOI		Amendment 6: Medium Access Control (MAC) Security
	10.1109/IEEESTD.2004.94585", IEEE 802.11i , 24 July 2004,		Enhancements", IEEE Std 802.11i-2004,
			DOI 10.1109/10.1109/IEEESTD.2004.94585, 24 July 2004,
	<https://ieeexplore.ieee.org/document/1318903>.		<https://ieeexplore.ieee.org/document/1318903>.
	[IEEE_802.1X]		[IEEE_802.1X]
	"IEEE 802.1X-2020 - IEEE Standard for Local and		IEEE, "IEEE Standard for Local and Metropolitan Area
	Metropolitan Area Networks--Port-Based Network Access		Networks--Port-Based Network Access Control", IEEE Std
	Control, DOI 10.1109/IEEESTD.2020.9018454", IEEE 802.1X ,		802.1X-2020, DOI 10.1109/IEEESTD.2020.9018454, 28 February
	28 February 2020,		2020, <https://ieeexplore.ieee.org/document/9018454>.
	<https://ieeexplore.ieee.org/document/9018454>.
	[IEEE_802.3]		[IEEE_802.3]
	"IEEE 802.3-2018 - IEEE Standard for Ethernet", IEEE		IEEE, "IEEE Standard for Ethernet", IEEE Std 802.3-2022,
	802.3 , 31 August 2018,		DOI 10.1109/IEEESTD.2022.9844436, 29 July 2022,
	<https://standards.ieee.org/ieee/802.3/7071/>.		<https://ieeexplore.ieee.org/document/9844436>.
	[IEEE_802E]		[IEEE_802E]
	"IEEE 802E-2020 - IEEE Recommended Practice for Privacy		IEEE, "IEEE Recommended Practice for Privacy
	Considerations for IEEE 802(R) Technologies", IEEE 802E ,		Considerations for IEEE 802(R) Technologies", IEEE Std
	13 November 2020,		802E-2020, DOI 10.1109/IEEESTD.2020.9018454, 13 November
	<https://standards.ieee.org/ieee/802E/6242/>.		2020, <https://ieeexplore.ieee.org/document/9257130>.
			[RADIUS] DeKok, A., "Deprecating Insecure Practices in RADIUS",
			Work in Progress, Internet-Draft, draft-ietf-radext-
			deprecating-radius-06, 25 May 2025,
			<https://datatracker.ietf.org/doc/html/draft-ietf-radext-
			deprecating-radius-06>.
	[RFC2131] Droms, R., "Dynamic Host Configuration Protocol",		[RFC2131] Droms, R., "Dynamic Host Configuration Protocol",
	RFC 2131, DOI 10.17487/RFC2131, March 1997,		RFC 2131, DOI 10.17487/RFC2131, March 1997,
	<https://www.rfc-editor.org/info/rfc2131>.		<https://www.rfc-editor.org/info/rfc2131>.
	[RFC3168] Ramakrishnan, K., Floyd, S., and D. Black, "The Addition		[RFC3168] Ramakrishnan, K., Floyd, S., and D. Black, "The Addition
	of Explicit Congestion Notification (ECN) to IP",		of Explicit Congestion Notification (ECN) to IP",
	RFC 3168, DOI 10.17487/RFC3168, September 2001,		RFC 3168, DOI 10.17487/RFC3168, September 2001,
	<https://www.rfc-editor.org/info/rfc3168>.		<https://www.rfc-editor.org/info/rfc3168>.
	skipping to change at page 18, line 37 ¶		skipping to change at line 856 ¶
	Converting Network Protocol Addresses to 48.bit Ethernet		Converting Network Protocol Addresses to 48.bit Ethernet
	Address for Transmission on Ethernet Hardware", STD 37,		Address for Transmission on Ethernet Hardware", STD 37,
	RFC 826, DOI 10.17487/RFC0826, November 1982,		RFC 826, DOI 10.17487/RFC0826, November 1982,
	<https://www.rfc-editor.org/info/rfc826>.		<https://www.rfc-editor.org/info/rfc826>.
	[RFC8837] Jones, P., Dhesikan, S., Jennings, C., and D. Druta,		[RFC8837] Jones, P., Dhesikan, S., Jennings, C., and D. Druta,
	"Differentiated Services Code Point (DSCP) Packet Markings		"Differentiated Services Code Point (DSCP) Packet Markings
	for WebRTC QoS", RFC 8837, DOI 10.17487/RFC8837, January		for WebRTC QoS", RFC 8837, DOI 10.17487/RFC8837, January
	2021, <https://www.rfc-editor.org/info/rfc8837>.		2021, <https://www.rfc-editor.org/info/rfc8837>.
			[WBA-OPENROAMING]
			Tomas, B., Grayson, M., Canpolat, N., Cockrell, B. A., and
			S. Gundavelli, "WBA OpenRoaming Wireless Federation", Work
			in Progress, Internet-Draft, draft-tomas-openroaming-05,
			15 April 2025, <https://datatracker.ietf.org/doc/html/
			draft-tomas-openroaming-05>.
	Appendix A. Existing Frameworks		Appendix A. Existing Frameworks
	A.1. 802.1X with WPA2 / WPA3		A.1. IEEE 802.1X with WPA2 / WPA3
	In typical enterprise Wi-Fi environment, 802.1X authentication		In a typical enterprise Wi-Fi environment, IEEE 802.1X authentication
	[IEEE_802.1X] coupled with WPA2 or WPA3 [IEEE_802.11i] encryption		[IEEE_802.1X] coupled with WPA2 or WPA3 [IEEE_802.11i] encryption
	schemes are commonly used for onboarding a Wi-Fi device. This allows		schemes are commonly used for onboarding a Wi-Fi device. This allows
	the mutual identification of the client device or the user of the		the mutual identification of the client device or the user of the
	device and an authentication authority. The authentication exchange		device and an authentication authority. The authentication exchange
	does not occur in clear text, and the user or the device identity can		does not occur in clear text, and the user or device identity can be
	be concealed from unauthorized observers. However, the		concealed from unauthorized observers. However, in most cases, the
	authentication authority is in most cases under the control of the		authentication authority is under the control of the same entity as
	same entity as the network access provider. This may lead to expose		the network access provider. This may lead to exposing the user or
	the user or device identity to the network owner.		device identity to the network owner.
	This scheme is well-adapted to enterprise environment, where a level		This scheme is well-adapted to an enterprise environment, where a
	of trust is established between the user and the enterprise network		level of trust is established between the user and the enterprise
	operator. In this scheme, MAC address randomization can occur		network operator. In this scheme, MAC address randomization can
	through brief disconnections and reconnections (under the rules of		occur through brief disconnections and reconnections (under the rules
	[IEEE_802.11bh]). Authentication may then need to reoccur, with an		of [IEEE_802.11bh]). Authentication may then need to reoccur, with
	associated cost of service disruption and additional load on the		an associated cost of service disruption, an additional load on the
	enterprise infrastructure, and an associated benefit of limiting the		enterprise infrastructure, and an associated benefit of limiting the
	exposure of a continuous MAC address to external observers. The		exposure of a continuous MAC address to external observers. The
	adoption of this scheme is limited outside of the enterprise		adoption of this scheme is limited outside of the enterprise
	environment by the requirement to install an authentication profile		environment by the requirement to install an authentication profile
	on the end device, which would be recognized and accepted by a local		on the end device, which would be recognized and accepted by a local
	authentication authority and its authentication server. Such a		authentication authority and its authentication server. Such a
	server is uncommon in a home environment, and the procedure to		server is uncommon in a home environment, and the procedure to
	install a profile is cumbersome for most untrained users. The		install a profile is cumbersome for most untrained users. The
	likelihood that a user or device profile would match a profile		likelihood that a user or device profile would match a profile
	recognized by a public Wi-Fi authentication authority is also fairly		recognized by a public Wi-Fi authentication authority is also fairly
	limited. This may restrict the adoption of this scheme for public		limited. This may restrict the adoption of this scheme for public
	Wi-Fi as well. Similar limitations are found in hospitality		Wi-Fi as well. Similar limitations are found in the hospitality
	environment. Hospitality environment refers to space provided by		environment. The hospitality environment refers to space provided by
	hospitality industry, which includes but not limited to hotels,		the hospitality industry, which includes but is not limited to
	stadiums, restaurants, concert halls and hospitals.		hotels, stadiums, restaurants, concert halls, and hospitals.
	A.2. OpenRoaming		A.2. OpenRoaming
	In order to alleviate some of the limitations listed above, the		In order to alleviate some of the limitations listed above, the
	Wireless Broadband Alliance (WBA) OpenRoaming Standard introduces an		Wireless Broadband Alliance (WBA) OpenRoaming standard introduces an
	intermediate trusted relay between local venues (places where some		intermediate trusted relay between local venues (places where some
	public Wi-Fi is available) and sources of identity		public Wi-Fi is available) and sources of identity [WBA-OPENROAMING].
	[I-D.tomas-openroaming]. The federation structure extends the type		The federation structure extends the type of authorities that can be
	of authorities that can be used as identity sources (compared to		used as identity sources (compared to the traditional enterprise-
	traditional enterprise-based 802.1X [IEEE_802.1X] scheme for Wi-Fi),		based IEEE 802.1X scheme for Wi-Fi [IEEE_802.1X]) and facilitates the
	and facilitates the establishment of trust between local networks and		establishment of trust between local networks and an identity
	an identity provider. Such a procedure increases the likelihood that		provider. Such a procedure increases the likelihood that one or more
	one or more identity profiles for the user or the device will be		identity profiles for the user or the device will be recognized by a
	recognized by a local network. At the same time, authentication does		local network. At the same time, authentication does not occur to
	not occur to the local network. This may offer the possibility for		the local network. This may offer the possibility for the user or
	the user or the device to keep their identity obfuscated from the		the device to keep their identity obfuscated from the local network
	local network operator, unless that operator specifically expresses		operator, unless that operator specifically expresses the requirement
	the requirement to disclose such identity (in which case the user has		to disclose such identity (in which case the user has the option to
	the option to accept or decline the connection and associated		accept or decline the connection and associated identity exposure).
	identity exposure).
	The OpenRoaming scheme seems well-adapted to public Wi-Fi and		The OpenRoaming scheme seems well-adapted to public Wi-Fi and
	hospitality environment. It defines a framework to protect the		hospitality environments. It defines a framework to protect the
	identity from unauthorized entities while to permit mutual		identity from unauthorized entities while permitting mutual
	authentication between the device or the user and a trusted identity		authentication between the device or the user and a trusted identity
	provider. Just like with standard 802.1X [IEEE_802.1X] scheme for		provider. Just like the standard IEEE 802.1X scheme for Wi-Fi
	Wi-Fi, authentication allows for the establishment of WPA2 or WPA3		[IEEE_802.1X], authentication allows for the establishment of WPA2 or
	keys [IEEE_802.11i] that can then be used to encrypt the		WPA3 keys [IEEE_802.11i] that can then be used to encrypt the
	communication between the device and the access point. The		communication between the device and the access point. The
	encryption adds extra protection to prevent the network traffic from		encryption adds extra protection to prevent the network traffic from
	being eavesdropped.		being eavesdropped.
	MAC address randomization can occur through brief disconnections and		MAC address randomization can occur through brief disconnections and
	reconnections (under the rules of [IEEE_802.11bh]). Authentication		reconnections (under the rules of [IEEE_802.11bh]). Authentication
	may then need to reoccur, with an associated cost of service		may then need to reoccur, with an associated cost of service
	disruption and additional load on the venue and identity provider		disruption, an additional load on the venue and identity provider
	infrastructure, and an associated benefit of limiting the exposure of		infrastructure, and an associated benefit of limiting the exposure of
	a continuous MAC address to external observers. Limitations of this		a continuous MAC address to external observers. Limitations of this
	scheme include the requirement to first install one or more profiles		scheme include the requirement to first install one or more profiles
	on the client device. This scheme also requires the local network to		on the client device. This scheme also requires the local network to
	support RADSEC [RFC6614] and the relay function, which may not be		support RADSEC [RFC6614] and the relay function, which may not be
	common in small hotspot networks and home environment.		common in small hotspot networks and home environments.
	It is worth noting that, as part of collaborations between IETF		It is worth noting that, as part of collaborations between the IETF
	MADINAS and WBA around OpenRoaming, some RADIUS privacy enhancements		MADINAS Working Group and WBA around OpenRoaming, some RADIUS privacy
	have been proposed in the IETF RADEXT group. For instance,		enhancements have been proposed in the IETF RADEXT Working Group.
	[I-D.ietf-radext-deprecating-radius] describes good practices in the		For instance, [RADIUS] describes good practices in the use of
	use of Chargeable-User-Identity (CUI) between different visited		Chargeable-User-Identity (CUI) between different visited networks,
	networks, making it better suited for Public Wi-Fi and Hospitality		making it better suited for public Wi-Fi and hospitality use cases.
	use cases.
	A.3. Proprietary RCM schemes		A.3. Proprietary RCM Schemes
	Most client device operating system vendors offer RCM schemes,		Most client device operating system vendors offer RCM schemes that
	enabled by default (or easy to enable) on client devices. With these		are enabled by default (or easy to enable) on client devices. With
	schemes, the device changes its MAC address, when not associated,		these schemes, the device changes its MAC address, when not
	after having used a given MAC address for a semi-random duration		associated, after having used a given MAC address for a semi-random
	window. These schemes also allow for the device to manifest a		duration window. These schemes also allow for the device to manifest
	different MAC address in different SSIDs.		a different MAC address in different SSIDs.
	Such a randomization scheme enables the device to limit the duration		Such a randomization scheme enables the device to limit the duration
	of exposure of a single MAC address to observers. In		of exposure of a single MAC address to observers. In
	[IEEE_802.11bh], MAC address randomization is not allowed during a		[IEEE_802.11bh], MAC address randomization is not allowed during a
	given association session, and MAC address randomization can only		given association session, and MAC address randomization can only
	occur through disconnection and reconnection. Authentication may		occur through disconnection and reconnection. Authentication may
	then need to reoccur, with an associated cost of service disruption		then need to reoccur, with an associated cost of service disruption
	and additional load on the venue and identity provider		and additional load on the venue and identity provider
	infrastructure, directly proportional to the frequency of the		infrastructure, directly proportional to the frequency of the
	randomization. The scheme is also not intended to protect from the		randomization. The scheme is also not intended to protect from the
End of changes. 123 change blocks.
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