< draft-bhandari-dhc-class-based-prefix-02.txt		draft-bhandari-dhc-class-based-prefix-03.txt >
	skipping to change at page 1, line 15 ¶		skipping to change at page 1, line 15 ¶
	Intended status: Standards Track S. Bandi		Intended status: Standards Track S. Bandi
	Expires: January 17, 2013 S. Gundavelli		Expires: January 17, 2013 S. Gundavelli
	Cisco Systems		Cisco Systems
	H. Deng		H. Deng
	China Mobile		China Mobile
	L. Thiebaut		L. Thiebaut
	Alcatel-Lucent		Alcatel-Lucent
	July 16, 2012		July 16, 2012
	DHCPv6 class based prefix		DHCPv6 class based prefix
	draft-bhandari-dhc-class-based-prefix-02		draft-bhandari-dhc-class-based-prefix-03
	Abstract		Abstract
	DHCPv6 defines class based allocation of IA_NA and IA_TA IPv6		DHCPv6 defines class based allocation of IA_NA and IA_TA IPv6
	addresses. This document extends DHCPv6 prefix delegation with class		addresses. This document extends DHCPv6 prefix delegation with class
	based prefix allocation. It defines a new usage class option to		based prefix allocation. It defines a new usage class option to
	classify a prefix. It defines the behavior of a DHCPv6 client		classify a prefix. It defines the behavior of a DHCPv6 client
	requesting a prefix to include the class of the prefix to be		requesting a prefix to include the class of the prefix to be
	allocated and the DHCPv6 server behavior to select and offer a prefix		allocated and the DHCPv6 server behavior to select and offer a prefix
	from a given class. It discusses how IA_NA can be requested and		from a given class. It discusses how IA_NA can be requested and
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	the Trust Legal Provisions and are provided without warranty as		the Trust Legal Provisions and are provided without warranty as
	described in the Simplified BSD License.		described in the Simplified BSD License.
	Table of Contents		Table of Contents
	1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3		1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
	1.1. Motivation . . . . . . . . . . . . . . . . . . . . . . . . 3		1.1. Motivation . . . . . . . . . . . . . . . . . . . . . . . . 3
	1.2. Terminology . . . . . . . . . . . . . . . . . . . . . . . 4		1.2. Terminology . . . . . . . . . . . . . . . . . . . . . . . 4
	1.3. Requirements Language . . . . . . . . . . . . . . . . . . 4		1.3. Requirements Language . . . . . . . . . . . . . . . . . . 4
	2. Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . 4		2. Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
	2.1. Usage Class Option . . . . . . . . . . . . . . . . . . . . 4		2.1. Usage Class Option . . . . . . . . . . . . . . . . . . . . 5
	2.2. Consideration for different DHCPv6 entities . . . . . . . 6		2.2. Consideration for different DHCPv6 entities . . . . . . . 6
	2.2.1. Requesting Router Behavior . . . . . . . . . . . . . . 6		2.2.1. Requesting Router Behavior for IA_PD allocation . . . 6
	2.2.2. Delegating Router Behavior . . . . . . . . . . . . . . 7		2.2.2. Delegating Router Behavior for IA_PD allocation . . . 7
	2.2.3. DHCPv6 Client Behavior for IA_NA allocation . . . . . 7		2.2.3. DHCPv6 Client Behavior for IA_NA allocation . . . . . 7
			2.2.4. DHCPv6 Server Behavior for IA_NA allocation . . . . . 8
	2.3. Usage . . . . . . . . . . . . . . . . . . . . . . . . . . 8		2.3. Usage . . . . . . . . . . . . . . . . . . . . . . . . . . 8
	2.3.1. OPTION_USAGE_CLASS Values . . . . . . . . . . . . . . 8		2.3.1. OPTION_USAGE_CLASS Values . . . . . . . . . . . . . . 8
	2.3.2. Class based prefix and IA_NA allocation . . . . . . . 8		2.3.2. Class based prefix and IA_NA allocation . . . . . . . 9
	2.3.3. Class based prefix and IA_PD allocation . . . . . . . 9		2.3.3. Class based prefix and IA_PD allocation . . . . . . . 9
	2.3.4. Class based prefix and SLAAC . . . . . . . . . . . . . 9		2.3.4. Class based prefix and SLAAC . . . . . . . . . . . . . 9
	2.3.5. Class based prefix and applications . . . . . . . . . 9		2.3.5. Class based Information-Request . . . . . . . . . . . 10
	3. Example Application . . . . . . . . . . . . . . . . . . . . . 9		2.3.6. Class based prefix and applications . . . . . . . . . 10
			3. Example Application . . . . . . . . . . . . . . . . . . . . . 10
	3.1. Class based prefix delegation . . . . . . . . . . . . . . 12		3.1. Class based prefix delegation . . . . . . . . . . . . . . 12
	3.2. IPv6 address assignment from class based prefix . . . . . 12		3.2. IPv6 address assignment from class based prefix . . . . . 12
	4. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 13		4. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 13
	5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 13		5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 13
	5.1. OPTION_USAGE_CLASS values . . . . . . . . . . . . . . . . 13		5.1. OPTION_USAGE_CLASS values . . . . . . . . . . . . . . . . 13
	6. Security Considerations . . . . . . . . . . . . . . . . . . . 14		6. Security Considerations . . . . . . . . . . . . . . . . . . . 14
	7. Change History (to be removed prior to publication as an		7. Change History (to be removed prior to publication as an
	RFC) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14		RFC) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
	8. References . . . . . . . . . . . . . . . . . . . . . . . . . . 14		8. References . . . . . . . . . . . . . . . . . . . . . . . . . . 14
	8.1. Normative References . . . . . . . . . . . . . . . . . . . 14		8.1. Normative References . . . . . . . . . . . . . . . . . . . 14
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	function as a DHCPv6 server there needs to be additional information		function as a DHCPv6 server there needs to be additional information
	in the delegated prefix that helps the requesting router to select		in the delegated prefix that helps the requesting router to select
	the address allocation for the DHCPv6 client it serves, from one of		the address allocation for the DHCPv6 client it serves, from one of
	the available delegated prefixes.		the available delegated prefixes.
	One way to select an address or longer prefix (from a delegated		One way to select an address or longer prefix (from a delegated
	prefix) to be allocated by a requesting router playing the role of a		prefix) to be allocated by a requesting router playing the role of a
	DHCPv6 server is by introducing additional options in IA_PD to be		DHCPv6 server is by introducing additional options in IA_PD to be
	matched with options for address selection in the DHCPv6 SOLICIT		matched with options for address selection in the DHCPv6 SOLICIT
	message. [RFC3315] defines the OPTION_USER_CLASS option which is		message. [RFC3315] defines the OPTION_USER_CLASS option which is
	used for selecting address for assignment. This document introduces		used for selecting address for assignment. But the OPTION_USER_CLASS
	OPTION_USAGE_CLASS option in IA_PD option for the purpose of		option is only loosely defined and it can hardly be used in mobile
	selecting a prefix for further delegation either via IA_NA or IA_PD		environment where a DHCPv6 client, the DHCPv6 server or requesting
	DHCPv6 request. It defines the behavior of the DHCPv6 server, the		router and the delegating Router may belong to different
	DHCPv6 prefix requesting router and the DHCPv6 client to use this		organizations.
	option.
			This document introduces OPTION_USAGE_CLASS option in IA_PD option
			for the purpose of selecting a prefix for further delegation either
			via IA_NA or IA_PD DHCPv6 request. It defines the behavior of the
			DHCPv6 server, the DHCPv6 prefix requesting router and the DHCPv6
			client to use this option.
	In IPv6 a network interface can acquire multiple addresses from the		In IPv6 a network interface can acquire multiple addresses from the
	same scope. In this case application need to have additional		same scope. In this case application need to have additional
	information about the prefix configured on the interface for source		information about the prefix configured on the interface for source
	address selection. Since the network address can be configured via		address selection. Since the network address can be configured via
	DHCPv6 as defined in [RFC3315] or via Stateless Address		DHCPv6 as defined in [RFC3315] or via Stateless Address
	Autoconfiguration (SLAAC) as defined in [RFC4862], additional		Autoconfiguration (SLAAC) as defined in [RFC4862], additional
	information of a prefix can be provided via DHCPv6 or via IPv6 Router		information of a prefix can be provided via DHCPv6 or via IPv6 Router
	Advertisement (RA).		Advertisement (RA).
	skipping to change at page 4, line 40 ¶		skipping to change at page 4, line 44 ¶
	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].
	2. Overview		2. Overview
	This section defines usage class option in IA_PD and IA_NA to aid		This section defines usage class option in IA_PD and IA_NA to aid
	class based prefix delegation and address assignment. This section		class based prefix delegation and address assignment. This section
	defines the behavior of the delegating router, the requesting router		defines the behavior of the delegating router, the requesting router
	and the DHCPv6 client.		and the DHCPv6 client. It defines also usage class option in the
			context of a DHCP information request from a DHCP client to a DHCP
			server.
	2.1. Usage Class Option		2.1. Usage Class Option
	The format of the DHCPv6 usage class option is shown below.		The format of the DHCPv6 usage class option is shown below.
	0 1 2 3		0 1 2 3
	0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1		0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	| OPTION_USAGE_CLASS | option-length(2) |		| OPTION_USAGE_CLASS | option-length(2) |
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	| Class | ~		| Class | ~
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+- ~		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+- ~
	~ Vendor Class Data (Optional,variable length) ~		~ Vendor Class Data (Optional,variable length) ~
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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	options in the allocated prefix as described in Section 2.2.2. The		options in the allocated prefix as described in Section 2.2.2. The
	requesting router is then responsible for the delegated prefix(es)		requesting router is then responsible for the delegated prefix(es)
	after the DHCPv6 REQUEST message exchange. For example, the		after the DHCPv6 REQUEST message exchange. For example, the
	requesting router may create DHCPv6 server configuration pools from		requesting router may create DHCPv6 server configuration pools from
	the delegated prefix, and function as a DHCPv6 Server. When the		the delegated prefix, and function as a DHCPv6 Server. When the
	requesting router then receives a DHCPv6 IA_NA requests it can select		requesting router then receives a DHCPv6 IA_NA requests it can select
	the address to be allocated based on the OPTION_USER_CLASS or		the address to be allocated based on the OPTION_USER_CLASS or
	OPTION_USAGE_CLASS options received in IA_NA request or any of the		OPTION_USAGE_CLASS options received in IA_NA request or any of the
	other methods as described in Section 2.3.1.		other methods as described in Section 2.3.1.
	2.2.1. Requesting Router Behavior		2.2.1. Requesting Router Behavior for IA_PD allocation
	DHCPv6 requesting router can request for prefixes in the following		DHCPv6 requesting router can request for prefixes in the following
	ways:		ways:
	o In the SOLICIT message within the IA_PD Prefix option, it MAY		o In the SOLICIT message within the IA_PD Prefix option, it MAY
	include OPTION_USAGE_CLASS requesting prefix delegation for the		include OPTION_USAGE_CLASS requesting prefix delegation for the
	specific class indicated in the OPTION_USAGE_CLASS option. It can		specific class indicated in the OPTION_USAGE_CLASS option. It can
	include multiple IA_PD Prefix options to indicate it's preference		include multiple IA_PD Prefix options to indicate it's preference
	for more than one usage class.		for more than one usage class.
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	classes that the DHCPv6 server can provide to this requesting		classes that the DHCPv6 server can provide to this requesting
	Router.		Router.
	The requesting router parses the OPTION_USAGE_CLASS option in		The requesting router parses the OPTION_USAGE_CLASS option in
	theOPTION_IAPREFIX option area of the corresponding IA_PD Prefix		theOPTION_IAPREFIX option area of the corresponding IA_PD Prefix
	option in the ADVERTISE message. The Requesting router MUST then		option in the ADVERTISE message. The Requesting router MUST then
	include all or subset of the received class based prefix(es) in the		include all or subset of the received class based prefix(es) in the
	REQUEST message so that it will be responsible for the prefixes		REQUEST message so that it will be responsible for the prefixes
	selected.		selected.
	2.2.2. Delegating Router Behavior		2.2.2. Delegating Router Behavior for IA_PD allocation
	If the Delegating router supports class based prefix allocation by		If the Delegating router supports class based prefix allocation by
	supporting the OPTION_USAGE_CLASS option and it is configured to		supporting the OPTION_USAGE_CLASS option and it is configured to
	assign prefixes from different classes, it selects prefixes for class		assign prefixes from different classes, it selects prefixes for class
	based prefix allocation in the following way:		based prefix allocation in the following way:
	o If requesting router includes OPTION_USAGE_CLASS within the IA_PD		o If requesting router includes OPTION_USAGE_CLASS within the IA_PD
	Prefix option, it selects prefixes to be offered from that		Prefix option, it selects prefixes to be offered from that
	specific class.		specific class.
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	2.2.3. DHCPv6 Client Behavior for IA_NA allocation		2.2.3. DHCPv6 Client Behavior for IA_NA allocation
	DHCPv6 client MAY request for an IA_NA address allocation from a		DHCPv6 client MAY request for an IA_NA address allocation from a
	specific usage class in the following way:		specific usage class in the following way:
	o In the SOLICIT message within the IA_NA option, it MAY include the		o In the SOLICIT message within the IA_NA option, it MAY include the
	OPTION_USAGE_CLASS requesting address to be allocated from a		OPTION_USAGE_CLASS requesting address to be allocated from a
	specific usage class indicated in that option.		specific usage class indicated in that option.
	The DHCPv6 server parses OPTION_USAGE_CLASS option received and		If DHCPv6 client receives OPTION_USAGE_CLASS option in the IAaddr-
	includes it in option area of corresponding OPTION_IA_NA in ADVERTISE		options area of the corresponding IA_NA but does not support this
	message.		option, it SHOULD ignore the received option.
			2.2.4. DHCPv6 Server Behavior for IA_NA allocation
			The DHCPv6 server parses OPTION_USAGE_CLASS option received and when
			it supports allocation within the requested OPTION_USAGE_CLASS
			responds with an ADVERTISE message after populating the IA_NA option
			with address information from the requested Usage class. Along with
			including the IA Address options in the IA_NA option, it also
			includes the OPTION_USAGE_CLASS option in the corresponding IAaddr-
			options area.
			Even though the IA_NA option in the SOLICIT message does not include
			the OPTION_USAGE_CLASS option, based on local policies, the DHCP
			server MAY select a default OPTION_USAGE_CLASS value for the client
			and then SHOULD include the OPTION_USAGE_CLASS option in the IAaddr-
			options area of the corresponding IA_NA it sends to the client. If
			both DHCP client and server support Usage-class-based address
			allocation, but the DHCP server cannot offer addresses in the
			specified Usage class then the DHCP server MUST include the status
			code NoAddrsAvail (as defined in [RFC3315]) in the response message.
			If the DHCP server cannot offer addresses for any other reason, it
			MUST respond to requesting router with appropriate status code as
			specified in [RFC3315].
	2.3. Usage		2.3. Usage
	Class based prefix delegation can be used by the requesting router to		Class based prefix delegation can be used by the requesting router to
	configure itself as a DHCPv6 server to serve its DHCPv6 clients. It		configure itself as a DHCPv6 server to serve its DHCPv6 clients. It
	can allocate longer prefixes from a delegated shorter prefix it		can allocate longer prefixes from a delegated shorter prefix it
	received, for serving IA_NA and IA_PD requests.		received, for serving IA_NA and IA_PD requests.
	2.3.1. OPTION_USAGE_CLASS Values		2.3.1. OPTION_USAGE_CLASS Values
	skipping to change at page 9, line 30 ¶		skipping to change at page 10, line 5 ¶
	delegating router, its behavior is explained in Section 2.2.2.		delegating router, its behavior is explained in Section 2.2.2.
	2.3.4. Class based prefix and SLAAC		2.3.4. Class based prefix and SLAAC
	DHCPv6 IA_NA and IPv6 Stateless Address Autoconfiguration (SLAAC as		DHCPv6 IA_NA and IPv6 Stateless Address Autoconfiguration (SLAAC as
	defined in [RFC4862]) are two ways by IPv6 addresses can be		defined in [RFC4862]) are two ways by IPv6 addresses can be
	dynamically assigned to end hosts. Making SLAAC class aware is		dynamically assigned to end hosts. Making SLAAC class aware is
	outside the scope of this document, it is specified in		outside the scope of this document, it is specified in
	[I-D.korhonen-dmm-prefix-properties].		[I-D.korhonen-dmm-prefix-properties].
	2.3.5. Class based prefix and applications		2.3.5. Class based Information-Request
			A DHCP client MAY include OPTION_USAGE_CLASS in the Information
			request message to indicate that the requested configuration
			information (such as a list of available DNS servers) may be
			associated with a specific Usage Class.The server responds to the
			client with the requested Options whose values are determined based
			on the received OPTION_USAGE_CLASS. Even though the Information
			request message does not include the OPTION_USAGE_CLASS option, based
			on local policies, the DHCP server MAY select a default
			OPTION_USAGE_CLASS value for the client and then SHOULD include the
			OPTION_USAGE_CLASS option Information Response it sends to the
			client.
			2.3.6. Class based prefix and applications
	Applications within a host can do source address selection based on		Applications within a host can do source address selection based on
	the class of the prefix learnt in OPTION_USAGE_CLASS using rules		the class of the prefix learnt in OPTION_USAGE_CLASS using rules
	defined in [RFC3484].		defined in [RFC3484].
	3. Example Application		3. Example Application
	The following sub-sections provide examples of class based prefix		The following sub-sections provide examples of class based prefix
	delegation and how it is used in a mobile network. Each of the		delegation and how it is used in a mobile network. Each of the
	examples will refer to the below network:		examples will refer to the below network:
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