< draft-ietf-savi-mix-06.txt		draft-ietf-savi-mix-07.txt >
	SAVI J. Bi		SAVI J. Bi
	Internet-Draft G. Yao		Internet-Draft G. Yao
	Intended status: Standards Track Tsinghua Univ.		Intended status: Standards Track Tsinghua Univ.
	Expires: November 17, 2014 J. Halpern		Expires: September 9, 2015 J. Halpern
	Newbridge		Newbridge
	E. Levy-Abegnoli, Ed.		E. Levy-Abegnoli, Ed.
	Cisco		Cisco
	May 16, 2014		March 8, 2015
	SAVI for Mixed Address Assignment Methods Scenario		SAVI for Mixed Address Assignment Methods Scenario
	draft-ietf-savi-mix-06		draft-ietf-savi-mix-07
	Abstract		Abstract
	This document reviews how multiple address discovery methods can		In case that multiple IP address assignment methods are allowed in a
	coexist in a single SAVI device and collisions are resolved when the		network, the corresponding SAVI methods should be enabled to prevent
	same binding entry is discovered by two or more methods.		spoofing in the network. This document reviews how multiple SAVI
			methods can coexist in a single SAVI device and collisions are
			resolved when the same binding entry is discovered by two or more
			methods.
	Status of this Memo		Status of This Memo
	This Internet-Draft is submitted in full conformance with the		This Internet-Draft is submitted in full conformance with the
	provisions of BCP 78 and BCP 79.		provisions of BCP 78 and BCP 79.
	Internet-Drafts are working documents of the Internet Engineering		Internet-Drafts are working documents of the Internet Engineering
	Task Force (IETF). Note that other groups may also distribute		Task Force (IETF). Note that other groups may also distribute
	working documents as Internet-Drafts. The list of current Internet-		working documents as Internet-Drafts. The list of current Internet-
	Drafts is at http://datatracker.ietf.org/drafts/current/.		Drafts is at http://datatracker.ietf.org/drafts/current/.
	Internet-Drafts are draft documents valid for a maximum of six months		Internet-Drafts are draft documents valid for a maximum of six months
	and may be updated, replaced, or obsoleted by other documents at any		and may be updated, replaced, or obsoleted by other documents at any
	time. It is inappropriate to use Internet-Drafts as reference		time. It is inappropriate to use Internet-Drafts as reference
	material or to cite them other than as "work in progress."		material or to cite them other than as "work in progress."
	This Internet-Draft will expire on November 17, 2014.		This Internet-Draft will expire on September 9, 2015.
	Copyright Notice		Copyright Notice
	Copyright (c) 2014 IETF Trust and the persons identified as the		Copyright (c) 2015 IETF Trust and the persons identified as the
	document authors. All rights reserved.		document authors. All rights reserved.
	This document is subject to BCP 78 and the IETF Trust's Legal		This document is subject to BCP 78 and the IETF Trust's Legal
	Provisions Relating to IETF Documents		Provisions Relating to IETF Documents
	(http://trustee.ietf.org/license-info) in effect on the date of		(http://trustee.ietf.org/license-info) in effect on the date of
	publication of this document. Please review these documents		publication of this document. Please review these documents
	carefully, as they describe your rights and restrictions with respect		carefully, as they describe your rights and restrictions with respect
	to this document. Code Components extracted from this document must		to this document. Code Components extracted from this document must
	include Simplified BSD License text as described in Section 4.e of		include Simplified BSD License text as described in Section 4.e of
	the Trust Legal Provisions and are provided without warranty as		the Trust Legal Provisions and are provided without warranty as
	described in the Simplified BSD License.		described in the Simplified BSD License.
	This document may contain material from IETF Documents or IETF
	Contributions published or made publicly available before November
	10, 2008. The person(s) controlling the copyright in some of this
	material may not have granted the IETF Trust the right to allow
	modifications of such material outside the IETF Standards Process.
	Without obtaining an adequate license from the person(s) controlling
	the copyright in such materials, this document may not be modified
	outside the IETF Standards Process, and derivative works of it may
	not be created outside the IETF Standards Process, except to format
	it for publication as an RFC or to translate it into languages other
	than English.
	Table of Contents		Table of Contents
	1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3		1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
	2. Requirements Language . . . . . . . . . . . . . . . . . . . . 3		2. Requirements Language . . . . . . . . . . . . . . . . . . . . 3
	3. Problem Scope . . . . . . . . . . . . . . . . . . . . . . . . 3		3. Problem Scope . . . . . . . . . . . . . . . . . . . . . . . . 3
	4. Architecture . . . . . . . . . . . . . . . . . . . . . . . . . 4		4. Architecture . . . . . . . . . . . . . . . . . . . . . . . . 3
	5. Security Perimeter in SAVI MIX . . . . . . . . . . . . . . . . 5		5. Recommendations for preventing collisions . . . . . . . . . . 5
	6. Recommendations for preventing collisions . . . . . . . . . . 6		6. Resolving binding collisions . . . . . . . . . . . . . . . . 5
	7. Handing binding collisions . . . . . . . . . . . . . . . . . . 7		6.1. Same Address on Different Binding Anchors . . . . . . . . 5
	7.1. Same Address on Different Binding Anchors . . . . . . . . 7		6.1.1. Basic preference . . . . . . . . . . . . . . . . . . 6
	7.1.1. Basic preference . . . . . . . . . . . . . . . . . . . 7		6.1.2. Overwritten preference . . . . . . . . . . . . . . . 6
	7.1.2. Overwritten preference . . . . . . . . . . . . . . . . 7		6.1.3. Multiple SAVI Device Scenario . . . . . . . . . . . . 7
	7.1.3. Multiple SAVI Device Scenario . . . . . . . . . . . . 8		6.2. Same Address on the Same Binding Anchor . . . . . . . . . 7
	7.2. Same Address on the Same Binding Anchor . . . . . . . . . 8		7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 7
	8. Security Considerations . . . . . . . . . . . . . . . . . . . 9		8. Acknowledgment . . . . . . . . . . . . . . . . . . . . . . . 7
	9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 9		9. References . . . . . . . . . . . . . . . . . . . . . . . . . 7
	10. Acknowledgment . . . . . . . . . . . . . . . . . . . . . . . . 9		9.1. Normative References . . . . . . . . . . . . . . . . . . 7
	11. References . . . . . . . . . . . . . . . . . . . . . . . . . . 10		9.2. Informative References . . . . . . . . . . . . . . . . . 8
	11.1. Informative References . . . . . . . . . . . . . . . . . . 10		Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 8
	11.2. Normative References . . . . . . . . . . . . . . . . . . . 10
	Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 10
	1. Introduction		1. Introduction
	There are currently several documents [savi-fcfs], [savi-dhcp] and		There are currently several SAVI documents ([RFC6620], [savi-dhcp]
	[savi-send] that describe the different methods by which a switch can		and [RFC7219]) that describe the different methods by which a switch
	discover and record bindings between a node's layer3 address and a		can discover and record bindings between a node's IP address and a
	binding anchor and use that binding to perform Source Address		binding anchor and use that binding to perform source address
	Validation. Each of these documents specifies how to learn on-link		validation. Each of these documents specifies how to learn on-link
	addresses, based on the method used for their assignment,		addresses, based on the method used for their assignment,
	respectively: StateLess Autoconfiguration (SLAAC), Dynamic Host		respectively: StateLess Autoconfiguration (SLAAC), Dynamic Host
	Control Protocol (DHCP) and Secure Neighbor Discovery (SeND). Each		Control Protocol (DHCP) and Secure Neighbor Discovery (SeND). Each
	of these documents describes separately how one particular discovery		of these documents describes separately how one particular method
	method deals with address collisions (same address, different		deals with address collisions (same address, different binding
	anchor).		anchor).
	While multiple assignment methods can be used in the same layer2		While multiple IP assignment methods can be used in the same layer-2
	domain, a SAVI device might have to deal with a mix of binding		domain, a SAVI device might have to deal with a mix of SAVI methods.
	discovery methods. The purpose of this document is to provide		The purpose of this document is to provide recommendations to avoid
	recommendations to avoid collisions and to review collisions handling		collisions and to review collisions handling when two or more such
	when two or more such methods come up with competing bindings.		methods come up with competing bindings.
	2. Requirements Language		2. Requirements Language
	The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",		The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
	"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this		"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
	document are to be interpreted as described in RFC 2119 [rfc2119].		document are to be interpreted as described in RFC 2119 [RFC2119].
	3. Problem Scope		3. Problem Scope
	There are three address assignment methods identified and reviewed in		There are three IP address assignment methods identified and reviewed
	one of the SAVI document:		in one of the SAVI document:
	1. StateLess Address AutoConfiguration (SLAAC) - reviewed in		1. StateLess Address AutoConfiguration (SLAAC) - reviewed in SAVI-
	[savi-fcfs]		FCFS[RFC6620]
	2. Dynamic Host Control Protocol address assignment (DHCP) -		2. Dynamic Host Control Protocol address assignment (DHCP) -
	reviewed in [savi-dhcp]		reviewed in SAVI-DHCP[savi-dhcp]
	3. Secure Neighbor Discovery (SeND) address assignment, reviewed in		3. Secure Neighbor Discovery (SeND) address assignment, reviewed in
	[savi-send]		SAVI-SEND[RFC7219]
	Each address assignment method corresponds to a binding discovery		In addition, there is a fourth method for installing a bindings on
	method: SAVI-FCFS, SAVI-DHCP and SAVI-SeND. In addition, there is a		the switch, referred to as "manual". It is based on manual (address
	fourth method for installing a bindings on the switch, referred to as		or prefix) binding configuration and is reviewed in [RFC6620] and
	"manual". It is based on manual (address or prefix) binding		[RFC7039].
	configuration and is reviewed in [savi-fcfs] and [savi-framework].
	All combinations of address assignment methods can coexist within a		All combinations of address assignment methods can coexist within a
	layer2 domain. A SAVI device will have to implement the		layer-2 domain. A SAVI device will have to implement the
	corresponding SAVI discovery methods (referred to as a "SAVI		corresponding binding setup methods (referred to as a "SAVI method")
	solution") to enable Source Address Validation. If more than one		to enable Source Address Validation. If more than one SAVI method is
	SAVI solution is enabled on a SAVI device, the method is referred to		enabled on a SAVI device, the method is referred to as "mix address
	as "mix address assignment method" in this document.		assignment method" in this document.
	SAVI solutions are independent from each other, each one handling its		SAVI methods are independent from each other, each one handling its
	own entries. In the absence of reconciliation, each solution will		own entries. In the absence of reconciliation, each method will
	reject packets sourced with an address it did not discovered. To		reject packets sourced with an address it did not discovered. To
	prevent addresses discovered by one solution to be filtered out by		prevent addresses discovered by one method to be filtered out by
	another, the binding table should be shared by all the solutions.		another, the binding table should be shared by all the solutions.
	However this could create some conflict when the same entry is		However this could create some conflict when the same entry is
	discovered by two different methods: the purpose of this document is		discovered by two different methods: the purpose of this document is
	of two folds: provide recommendations and method to avoid conflicts,		of two folds: provide recommendations and method to avoid conflicts,
	and resolve conflicts if and when they happen. Collisions happening		and resolve conflicts if and when they happen. Collisions happening
	within a given solution are outside the scope of this document.		within a given method are outside the scope of this document.
	4. Architecture		4. Architecture
	A SAVI device may enable multiple SAVI methods. This mechanism,		A SAVI device may enable multiple SAVI methods. This mechanism,
	called SAVI-MIX, is proposed as a layer between the binding		called SAVI-MIX, is proposed as a arbiter of the binding generation
	generation algorithems and the binding database which contains the		algorithms, generating the final working binding entries Figure 1.
	working binding entries Figure 1. SAVI methods, i.e., SAVI-FCFS,
	SAVI-DHCP, SAVI-SEND, do not have exclusive binding tables. Once a
	SAVI method generates a candidate binding, it will request SAVI-MIX
	to set up a corresponding entry in the shared binding database, named
	Binding DB. Then SAVI-MIX will check if there is any conflict in the
	Binding DB. A new binding will be generated if there is no conflict.
	If there is a conflict, SAVI-MIX will determine whether replace the
	existing binding or reject the candidate binding based on the
	policies specified in Section 7. Whether the candidate binding can
	be install in the Binding DB will not be returned to the requesting
	SAVI method.
	Correspondingly, the packet filtering will not be performed by each		Once a SAVI method generates a candidate binding, it will request
	SAVI method separately. Instead, SAVI-MIX will perform filtering		SAVI-MIX to set up a corresponding entry in the binding table. Then
	based on the entries in the Binding DB.		SAVI-MIX will check if there is any conflict in the binding table. A
			new binding will be generated if there is no conflict. If there is a
			conflict, SAVI-MIX will determine whether to replace the existing
			binding or reject the candidate binding based on the policies
			specified in Section 6.
			The packet filtering will not be performed by each SAVI method
			separately. Instead, SAVI-MIX will perform filtering based on the
			entries in the binding table.
	+--------------------------------------------------------+		+--------------------------------------------------------+
	| |		| |
	| SAVI Device |		| SAVI Device |
	| |		| |
	| |		| |
	| +------+ +------+ +------+ |		| +------+ +------+ +------+ |
	| | SAVI | | SAVI | | SAVI | |		| | SAVI | | SAVI | | SAVI | |
	| | | | | | | |		| | | | | | | |
	| | FCFS | | DHCP | | SEND | |		| | FCFS | | DHCP | | SEND | |
	| +------+ +------+ +------+ |		| +------+ +------+ +------+ |
	| | | | |		| | | | Binding |
	| | | | Candidate Binding |		| | | | setup |
	| v v v |		| v v v requests |
	| +------------------------------+ |		| +------------------------------+ |
	| | | |		| | | |
	| | SAVI-MIX | |		| | SAVI-MIX | |
	| | | |		| | | |
	| +------------------------------+ |		| +------------------------------+ |
	| | |		| | |
	| v Final Binding |		| v Final Binding |
	| +--------------+ |		| +--------------+ |
	| | Binding | |		| | Binding | |
	| | | |		| | | |
	| | Database | |		| | Table | |
	| +--------------+ |		| +--------------+ |
	| |		| |
	+--------------------------------------------------------+		+--------------------------------------------------------+
	Figure 1: SAVI-Mix Architecture		Figure 1: SAVI-Mix Architecture
	5. Security Perimeter in SAVI MIX		Each entry in the binding table will contain the following fields:
	The perimeter of SAVI MIX is the union of the perimeter of each SAVI		1. IP source address
	method, as illustrated in Figure 2.		2. Binding anchor
	+-----------------+		3. Lifetime
	| |
	+----+ | +-----+ |
	| | | | | |
	| H1 | | |DHCP1| |
	| | | | | |
	| | | | | |
	+----+ | +-----+ |
	+-------|------------------------------+ | |
	| | | |
	| +---------+ +---------+ |
	| | SAVI | | SAVI | |
	| | |--------+ +--------| | |
	| +---------+ | | +---------+ |
	| | | |
	| +-------------+ |
	| | SWITCH-A | |
	| | | |
	| +-------------+ |
	| | | |
	| +---------+ | | +---------+ |
	| | SAVI | | | | SAVI | |
	| | |--------+ +--------| | |
	| +---------+ +---------+ |
	| | | |
	| | +----------------------------|---------+
	| | | |
	| +----+ | +----+
	| | | | | |
	| | R1 | | | H2 |
	| | | | | |
	| | | | | |
	| +----+ | +----+
	| |
	+-----------------+
	Figure 2: SAVI-Mix Perimeter		4. Creation time
	6. Recommendations for preventing collisions		5. Binding methods: the methods which request the binding setup.
			5. Recommendations for preventing collisions
	If each solution has a dedicated address space, collisions won't		If each solution has a dedicated address space, collisions won't
	happen. Using non overlapping address space across SAVI solutions is		happen. Using non overlapping address space across SAVI solutions is
	therefore recommended. To that end, one should:		therefore recommended. To that end, one should:
	1. DHCP/SLAAC: use non-overlapping prefix for DHCP and SLAAC. Set		1. DHCP/SLAAC: use non-overlapping prefix for DHCP and SLAAC. Set
	the A bit in Prefix information option of Router Advertisement		the A bit in Prefix information option of Router Advertisement
	for SLAAC prefix. And set the M bit in Router Advertisement for		for SLAAC prefix, and set the M bit in Router Advertisement for
	DHCP prefix. For detail explanations on these bits, refer to		DHCP prefix. For detail explanations on these bits, refer to
	[rfc4861][rfc4862].		[RFC4861][RFC4862].
	2. SeND/non-SeND: avoid mixed environment (where SeND and non-SeND		2. SeND/non-SeND: avoid mixed environment (where SeND and non-SeND
	nodes are deployed) or separate the prefixes announced to SeND		nodes are deployed) or separate the prefixes announced to SeND
	and non-SenD nodes. One way to separate the prefixes is to have		and non-SenD nodes. One way to separate the prefixes is to have
	the router(s) announcing different (non-overlapping) prefixes to		the router(s) announcing different (non-overlapping) prefixes to
	SeND and to non-SeND nodes, using unicast Router Advertisements,		SeND and to non-SeND nodes, using unicast Router Advertisements,
	in response to SeND/non-SeND Router Solicit.		in response to SeND/non-SeND Router Solicit.
	7. Handing binding collisions		6. Resolving binding collisions
	In situations where collisions could not be avoided, two cases should		In situations where collisions could not be avoided, two cases should
	be considered:		be considered:
	1. The same address is bound on two different binding anchors by		1. The same address is bound on two different binding anchors by
	different SAVI solutions.		different SAVI methods.
	2. The same address is bound on the same binding anchor by different		2. The same address is bound on the same binding anchor by different
	SAVI solutions.		SAVI methods.
	7.1. Same Address on Different Binding Anchors		6.1. Same Address on Different Binding Anchors
	This would typically occur in case assignment address spaces could		This would typically occur in case assignment address spaces could
	not be separated. For instance,overl an address is assigned by SLAAC		not be separated. For instance, an address is assigned by SLAAC on
	on node X, installed in the binding table using SAVI-FCFS, anchored		node X, installed in the binding table using SAVI-FCFS, anchored to
	to "anchor-X". Later, the same address is assigned by DHCP to node		"anchor-X". Later, the same address is assigned by DHCP to node Y,
	Y, as a potential candidate in the same binding table, anchored to		and SAVI-DHCP will generate a candidate binding entry, anchored to
	"anchor-Y".		"anchor-Y".
	7.1.1. Basic preference		6.1.1. Basic preference
	The SAVI device must decide whom the address should be bound with		The SAVI device must decide whom the address should be bound with
	(anchor-X or anchor-Y in this example). Current standard documents		(anchor-X or anchor-Y in this example). Current standard documents
	of address assignment methods have implied the prioritization		of address assignment methods have implied the prioritization
	relationship (first-come). In the absence of any configuration or		relationship (first-come). In the absence of any configuration or
	protocol hint (see Section 7.1.2) the SAVI device should choose the		protocol hint (see Section 6.1.2) the SAVI device should choose the
	first-come entry, whether it was learnt from SLACC, SeND or DHCP.		first-come binding anchor, whether it was learnt from SLACC, SeND or
			DHCP.
	7.1.2. Overwritten preference		6.1.2. Overwritten preference
	There are two identified exceptions to the general prioritization		There are two identified exceptions to the general prioritization
	model, one of them being CGA addresses, another one controlled by the		model, one of them being CGA addresses, another one controlled by the
	configuration of the switch:		configuration of the switch.
	1. When CGA addresses are used, and a collision is detected,		6.1.2.1. CGA preference
	preference should be given to the anchor that carries the CGA
	credentials once they are verified, in particular the CGA
	parameters and the RSA options. Note that if an attacker was
	trying to replay CGA credentials, he would then compete on the
	base of fcfs (first-come, first-serve).
	2. The SAVI device should allow the configuration of a triplet		When CGA addresses are used, and a collision is detected, preference
	("prefix", "anchor", "method") or ("address", "anchor",		should be given to the anchor that carries the CGA credentials once
	"method"). Later, if a DAD message is received for a target		they are verified, in particular the CGA parameters and the RSA
	within "prefix" (or equal "address") bound to "anchor1"		options. Note that if an attacker was trying to replay CGA
	(different from "anchor"), or via a discovery method different		credentials, he would then compete on the base of fcfs (first-come,
	from "method", the switch should defend the address by responding		first-serve).
	to the DAD message. It should not at this point install the
	entry into the binding table. It will simply prevent the node to
	assign the address, and will de-facto prioritize the configured
	anchor or configured assignment method for that address. This is
	especially useful to protect well known bindings such as a static
	address of a server over anybody, even when the server is down.
	It is also a way to give priority to a binding learnt from SAVI-
	DHCP over a binding for the same address, learnt from SAVI-FCFS.
	7.1.3. Multiple SAVI Device Scenario		6.1.2.2. configuration preference
			For configuration driven exceptions, the SAVI device may allow the
			configuration of a triplet ("prefix", "anchor", "method") or
			("address", "anchor", "method"), where at least one of ("anchor",
			"method") should be specified. Later, if a DAD message is received
			with the following conditions verified:
			1. The target in the DAD message does not exist in the binding table
			2. The target is within configured "prefix" (or equal to "address")
			3. The anchor bound to target is different from the configured
			anchor, when specified
			4. The configured method, if any, is different from SAVI-FCFS
			the switch should defend the address by responding to the DAD
			message. It should not at this point install the entry into the
			binding table. It will simply prevent the node to assign the
			address, and will de-facto prioritize the configured anchor. This is
			especially useful to protect well known bindings such as a static
			address of a server over anybody, even when the server is down. It
			is also a way to give priority to a binding learnt from SAVI-DHCP
			over a binding for the same address, learnt from SAVI-FCFS.
			6.1.3. Multiple SAVI Device Scenario
	A single SAVI device doesn't have the information of all bound		A single SAVI device doesn't have the information of all bound
	addresses on the perimeter. Therefore it is not enough to lookup		addresses on the perimeter. Therefore it is not enough to lookup
	local bindings to identify a collision. However, assuming DAD is		local bindings to identify a collision. However, assuming DAD is
	performed throughout the security perimeter for all addresses		performed throughout the security perimeter for all addresses
	regardless of the assignment method, then DAD response will inform		regardless of the assignment method, then DAD response will inform
	all SAVI devices about any collision. In that case, FCFS will apply		all SAVI devices about any collision. In that case, FCFS will apply
	the same way as in a single switch scenario. If the admin configured		the same way as in a single switch scenario. If the admin configured
	on one the switches a prefix (or a single static binding) to defend,		on one the switches a prefix (or a single static binding) to defend,
	the DAD response generated by this switch will also prevent the		the DAD response generated by this switch will also prevent the
	binding to be installed on other switches of the perimeter.		binding to be installed on other switches of the perimeter.
	7.2. Same Address on the Same Binding Anchor		6.2. Same Address on the Same Binding Anchor
	A binding may be set up on the same binding anchor by multiple		A binding may be set up on the same binding anchor by multiple
	solutions. For example, if SAVI-FCFS and SAVI-DHCP are both enabled		methods, typically SAVI-FCFS and SAVI-DHCP. If the binding lifetimes
	on one SAVI device, a DHCP address be bound by both SAVI instances.		obtained from the two methods are different, priority should be given
			to 1) Manual configuration 2) SAVI-DHCP 3) SAVI-FCFS as the least
	There is no conflict if the binding is valid in all the solutions.		authoritative. The binding will be removed when the prioritized
	However, the binding lifetimes of different solutions can be		lifetime expires, even if a less authoritative method had a longer
	different. If one SAVI instance changes the state of a binding to		lifetime.
	invalid on lifetime expires, conflict will happen.
	The solution proposed is to keep a binding as long as possible. A
	binding is kept until it has been required to be removed by all the
	solutions that ever set up it.
	8. Security Considerations
	As described in [savi-framework], this solution cannot strictly
	prevent spoofing. There are two scenarios in which spoofing can
	still happen:
	1. The binding anchor is spoofable. if the binding anchor is
	spoofable, e.g., plain MAC address, an attacker can use forged
	binding anchor to send packet which will not be regarded as
	spoofing by SAVI device. Indeed, using binding anchor that can
	be easily spoofed is dangerous. An attacker can use the binding
	anchor of another host to perform a lot of DHCP procedures, and
	the SAVI device will refuse to set up new binding for the host
	whenever the binding number limitation has been reached. Thus,
	it is RECOMMENDED to use strong enough binding anchor, e.g.,
	switch port, secure association in 802.11ae/af and 802.11i.
	2. The binding anchor is shared by more than one host. If the
	binding anchor is shared by more than one host, they can spoof
	the addresses of each other. For example, a number of hosts can
	attach to the same switch port of a SAVI device through a hub.
	The SAVI device cannot distinguish packets from different hosts
	and thus the spoofing between them will not be detected. This
	problem can be solved through not sharing binding anchor between
	hosts.
	9. IANA Considerations		7. IANA Considerations
	This memo asks the IANA for no new parameters.		This memo asks the IANA for no new parameters.
	Note to RFC Editor: This section will have served its purpose if it		8. Acknowledgment
	correctly tells IANA that no new assignments or registries are
	required, or if those assignments or registries are created during
	the RFC publication process. From the authors' perspective, it may
	therefore be removed upon publication as an RFC at the RFC Editor's
	discretion.
	10. Acknowledgment
	Thanks to Christian Vogt, Eric Nordmark, Marcelo Bagnulo Braun and		Thanks to Christian Vogt, Eric Nordmark, Marcelo Bagnulo Braun and
	Jari Arkko for their valuable contributions.		Jari Arkko for their valuable contributions.
	This document was generated using the xml2rfc tool.		This document was generated using the xml2rfc tool.
	11. References		9. References
	11.1. Informative References		9.1. Normative References
	[rfc2119] Bradner, S., "Key words for use in RFCs to Indicate		[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
	Requirement Levels", RFC 2119, BCP 14, Match 1997.		Requirement Levels", BCP 14, RFC 2119, March 1997.
	11.2. Normative References		[RFC7039] Wu, J., Bi, J., Bagnulo, M., Baker, F., and C. Vogt,
			"Source Address Validation Improvement (SAVI) Framework",
			RFC 7039, October 2013.
	[rfc4861] Narten, T., Nordmark, E., Simpson, W., and H. Soliman,		[RFC6620] Nordmark, E., Bagnulo, M., and E. Levy-Abegnoli, "FCFS
	"Neighbor Discovery for IP version 6 (IPv6)", RFC 4861,		SAVI: First-Come, First-Served Source Address Validation
	September 2007.		Improvement for Locally Assigned IPv6 Addresses", RFC
			6620, May 2012.
	[rfc4862] Thomson, S., Narten, T., and T. Jinmei, "IPv6 Stateless		[RFC7219] Bagnulo, M. and A. Garcia-Martinez, "SEcure Neighbor
	Address Autoconfiguration", RFC 4862, September 2007.		Discovery (SEND) Source Address Validation Improvement
			(SAVI)", RFC 7219, May 2014.
	[savi-dhcp]		[savi-dhcp]
	Bi, J., Wu, J., Yao, G., and F. Baker, "SAVI Solution for		Bi, J., Wu, J., Yao, G., and F. Baker, "SAVI Solution for
	DHCP", draft-ietf-savi-dhcp-18 (work in progress),		DHCP", draft-ietf-savi-dhcp-34 (work in progress), Feb
	February 2012.		2015.
	[savi-fcfs]		9.2. Informative References
	Nordmark, E., Bagnulo, M., and E. Levy-Abegnoli, "FCFS-
	SAVI: First-Come First-Serve Source-Address Validation for
	Locally Assigned Addresses", RFC 6620, May 2012.
	[savi-framework]		[RFC4861] Narten, T., Nordmark, E., Simpson, W., and H. Soliman,
	Wu, J., Bi, J., Bagnulo, M., Baker, F., and C. Vogt, Ed.,		"Neighbor Discovery for IP version 6 (IPv6)", RFC 4861,
	"Source Address Validation Improvement Framework",		September 2007.
	RFC 7039, October 2013.
	[savi-send]		[RFC4862] Thomson, S., Narten, T., and T. Jinmei, "IPv6 Stateless
	Bagnulo, M. and A. Garcia-Martinez, "SEND-based Source-		Address Autoconfiguration", RFC 4862, September 2007.
	Address Validation Implementation",
	draft-ietf-savi-send-06 (work in progress), October 2011.
	Authors' Addresses		Authors' Addresses
	Jun Bi		Jun Bi
	Tsinghua University		Tsinghua University
	Network Research Center, Tsinghua University		Network Research Center, Tsinghua University
	Beijing 100084		Beijing 100084
	China		China
	Email: junbi@tsinghua.edu.cn		EMail: junbi@tsinghua.edu.cn
	Guang Yao		Guang Yao
	Tsinghua University		Tsinghua University
	Network Research Center, Tsinghua University		Network Research Center, Tsinghua University
	Beijing 100084		Beijing 100084
	China		China
	Email: yaoguang@cernet.edu.cn		EMail: yaoguang.china@gmail.com
	Joel M. Halpern		Joel M. Halpern
	Newbridge Networks Inc		Newbridge Networks Inc
	Email: jmh@joelhalpern.com		EMail: jmh@joelhalpern.com
	Eric Levy-Abegnoli (editor)		Eric Levy-Abegnoli (editor)
	Cisco Systems		Cisco Systems
	Village d'Entreprises Green Side - 400, Avenue Roumanille		Village d'Entreprises Green Side - 400, Avenue Roumanille
	Biot-Sophia Antipolis 06410		Biot-Sophia Antipolis 06410
	France		France
	Email: elevyabe@cisco.com		EMail: elevyabe@cisco.com
End of changes. 63 change blocks.
	244 lines changed or deleted		171 lines changed or added
This html diff was produced by rfcdiff 1.48. The latest version is available from http://tools.ietf.org/tools/rfcdiff/