draft-ietf-16ng-ps-goals-03.txt		draft-ietf-16ng-ps-goals-04.txt
	16ng Working Group J. Jee, Editor		Network Working Group J. Jee, Editor
	Internet-Draft ETRI		Internet-Draft ETRI
	Intended status: Informational S. Madanapalli		Intended status: Informational S. Madanapalli
	Expires: May 21, 2008 LogicaCMG		Expires: June 21, 2008 Ordyn Technologies
	J. Mandin		J. Mandin
	Runcom		Runcom
	G. Montenegro		December 19, 2007
	Microsoft
	S. Park
	Samsung Electronics
	M. Riegel
	NSN
	November 18, 2007
	IP over 802.16 Problem Statement and Goals		IP over 802.16 Problem Statement and Goals
	draft-ietf-16ng-ps-goals-03.txt		draft-ietf-16ng-ps-goals-04.txt
	Status of this Memo		Status of this Memo
	By submitting this Internet-Draft, each author represents that any		By submitting this Internet-Draft, each author represents that any
	applicable patent or other IPR claims of which he or she is aware		applicable patent or other IPR claims of which he or she is aware
	have been or will be disclosed, and any of which he or she becomes		have been or will be disclosed, and any of which he or she becomes
	aware will be disclosed, in accordance with Section 6 of BCP 79.		aware will be disclosed, in accordance with Section 6 of BCP 79.
	Internet-Drafts are working documents of the Internet Engineering		Internet-Drafts are working documents of the Internet Engineering
	Task Force (IETF), its areas, and its working groups. Note that		Task Force (IETF), its areas, and its working groups. Note that
	skipping to change at page 1, line 43		skipping to change at page 1, line 37
	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."
	The list of current Internet-Drafts can be accessed at		The list of current Internet-Drafts can be accessed at
	http://www.ietf.org/ietf/1id-abstracts.txt.		http://www.ietf.org/ietf/1id-abstracts.txt.
	The list of Internet-Draft Shadow Directories can be accessed at		The list of Internet-Draft Shadow Directories can be accessed at
	http://www.ietf.org/shadow.html.		http://www.ietf.org/shadow.html.
	This Internet-Draft will expire on May 21, 2008.		This Internet-Draft will expire on June 21, 2008.
	Copyright Notice		Copyright Notice
	Copyright (C) The IETF Trust (2007).		Copyright (C) The IETF Trust (2007).
	Abstract		Abstract
	This document specifies problems in running the IETF IP protocols		This document specifies problems in running the IETF IP protocols
	over IEEE 802.16 networks by identifying specific gaps in the 802.16		over IEEE 802.16 networks by identifying specific gaps in the 802.16
	MAC for IPv4 and IPv6 support. This document also provides an		MAC for IPv4 and IPv6 support. This document also provides an
	overview of IEEE 802.16 network characteristics and convergence		overview of IEEE 802.16 network characteristics and convergence
	sublayers. The common terminology to be used for the base guideline		sublayers. Common terminology used for the base guideline while
	while defining the solution frameworks is also presented.		defining the solution framework is also presented.
	Table of Contents		Table of Contents
	1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3		1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
	2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 4		2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 4
	3. Overview of the IEEE 802.16-2004 MAC layer . . . . . . . . . . 5		3. Overview of the IEEE 802.16 MAC layer . . . . . . . . . . . . 5
	3.1. Transport Connections . . . . . . . . . . . . . . . . . . 5		3.1. Transport Connections . . . . . . . . . . . . . . . . . . 5
	3.2. 802.16 PDU format . . . . . . . . . . . . . . . . . . . . 5		3.2. 802.16 PDU format . . . . . . . . . . . . . . . . . . . . 5
	3.3. 802.16 Convergence Sublayer . . . . . . . . . . . . . . . 6		3.3. 802.16 Convergence Sublayer . . . . . . . . . . . . . . . 6
	4. IP over IEEE 802.16 Problem Statement and Goals . . . . . . . 7		4. IP over IEEE 802.16 Problem Statement and Goals . . . . . . . 7
	4.1. Root Problem . . . . . . . . . . . . . . . . . . . . . . . 7		4.1. Root Problem . . . . . . . . . . . . . . . . . . . . . . . 7
	4.2. Point-to-Point Link model for IP CS: Problems . . . . . . 9		4.2. Point-to-Point Link model for IP CS: Problems . . . . . . 9
	4.3. Ethernet like Link model for Ethernet CS: Problems . . . . 10		4.3. Ethernet-like Link model for Ethernet CS: Problems . . . . 10
	4.4. IP over IEEE 802.16 Goals . . . . . . . . . . . . . . . . 11		4.4. IP over IEEE 802.16 Goals . . . . . . . . . . . . . . . . 11
	5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 11		5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 11
	6. Security Considerations . . . . . . . . . . . . . . . . . . . 11		6. Security Considerations . . . . . . . . . . . . . . . . . . . 11
	7. Acknowledgment . . . . . . . . . . . . . . . . . . . . . . . . 11		7. Contributors . . . . . . . . . . . . . . . . . . . . . . . . . 12
	8. References . . . . . . . . . . . . . . . . . . . . . . . . . . 12		8. Acknowledgment . . . . . . . . . . . . . . . . . . . . . . . . 12
	8.1. Normative References . . . . . . . . . . . . . . . . . . . 12		9. References . . . . . . . . . . . . . . . . . . . . . . . . . . 12
	8.2. Informative References . . . . . . . . . . . . . . . . . . 12		9.1. Normative References . . . . . . . . . . . . . . . . . . . 12
	Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 12		9.2. Informative References . . . . . . . . . . . . . . . . . . 13
			Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 13
	Intellectual Property and Copyright Statements . . . . . . . . . . 14		Intellectual Property and Copyright Statements . . . . . . . . . . 14
	1. Introduction		1. Introduction
	Broadband Wireless Access networks address the inadequacies of low		Broadband Wireless Access networks address the inadequacies of low
	bandwidth wireless communication for user requirements such as high		bandwidth wireless communication for user requirements such as high
	quality data/voice service, fast mobility, wide coverage, etc. The		quality data/voice service, fast mobility, wide coverage, etc. The
	IEEE 802.16 Working Group on Broadband Wireless Access Standards		IEEE 802.16 Working Group on Broadband Wireless Access Standards
	develops standards and recommended practices to support the		develops standards and recommended practices to support the
	development and deployment of broadband Wireless Metropolitan Area		development and deployment of broadband Wireless Metropolitan Area
	Networks [IEEE802.16].		Networks [IEEE802.16].
	Recently, the WiMAX Forum, and, in particular, its NWG (Network		Recently the WiMAX Forum, and in particular, its NWG (Network Working
	Working Group) is defining the IEEE 802.16 network architecture		Group) is defining the IEEE 802.16 network architecture (e.g. IPv4,
	(e.g., IPv4, IPv6, Mobility, Interworking with different networks,		IPv6, Mobility, Interworking with different networks, AAA, etc). The
	AAA, etc). The NWG is thus taking on work at layers above those		NWG is thus taking on work at layers above those defined by the IEEE
	defined by the IEEE 802 standards (typically limited to the physical		802 standards (typically limited to the physical and link-layers
	and link layers only). Similarly, WiBro (Wireless Broadband), a		only). Similarly, WiBro (Wireless Broadband), a Korean effort which
	Korean effort which focuses on the 2.3 GHz spectrum band, is also		focuses on the 2.3 GHz spectrum band, is also based on the IEEE
	based on the IEEE 802.16 specification [IEEE802.16].		802.16 specification [IEEE802.16].
	802.16 [IEEE802.16] is point-to-point and connection-oriented at the		802.16 [IEEE802.16] is point-to-point and connection-oriented at the
	MAC, physically arranged in a point-to-multipoint structure with the		MAC, physically arranged in a point-to-multipoint structure with the
	BS terminating one end of each connection and an individual SS		BS terminating one end of each connection and an individual SS
	terminating the other end of each connection. The 802.16 convergence		terminating the other end of each connection. The 802.16 convergence
	sublayer (CS) is at the uppermost part of the MAC that is responsible		sublayer (CS) is at the uppermost part of the MAC that is responsible
	for assigning transmit-direction Service Data Units (originating from		for assigning transmit-direction Service Data Units (originating from
	a higher layer application - eg. an IP or Ethernet at the BS or SS)		a higher layer application, e.g., IP or Ethernet at the BS or SS) to
	to a specific outbound transport connection. 802.16 defines two		a specific outbound transport connection. 802.16 defines two
	convergence sublayer types, the ATM CS and the Packet CS. The IP		convergence sublayer types, the ATM CS and the Packet CS. The IP
	Specific Subpart (IP CS) and the 802.3 Ethernet Specific Subpart		Specific Subpart (IP CS) and the 802.3 Ethernet Specific Subpart
	(Ethernet CS) of Packet CS is within the current 16ng WG scope.		(Ethernet CS) of Packet CS are within the current 16ng WG scope.
	There exists complexity in configuring the IP Subnet over IEEE 802.16		There is complexity in configuring the IP Subnet over IEEE 802.16
	network because of its point-to-point connection oriented feature and		network because of its point-to-point connection-oriented feature and
	the existence of IP CS and Ethernet CS which assume different higher		the existence of IP CS and Ethernet CS which assume different higher-
	layer functionality. IP Subnet is a topological area that uses the		layer functionality. An IP Subnet is a topological area that uses
	same IP address prefix where that prefix is not further subdivided		the same IP address prefix where that prefix is not further
	except into individual addresses as specified from [RFC4903]. The IP		subdivided except into individual addresses as specified in
	Subnet configuration is dependent on the underlying link layer's		[RFC4903]. The IP Subnet configuration is dependent on the
	characteristic and decides the overall IP operation on the network.		underlying link-layer's characteristic and decides the overall IP
	The IP CS and Ethernet CS of IEEE 802.16 assume different higher		operation on the network. The IP CS and Ethernet CS of IEEE 802.16
	layer capability, like the IP routing functionality in case of IP CS		assume different higher layer capabilities: IP routing functionality
	and the bridging functionality in case of Ethernet CS. This means		in the case of IP CS and bridging functionality in the case of
	that underlying link layer's characteristics beneath IP can change		Ethernet CS. This means that the link-layer's characteristics
	according to the adopted convergence sublayers.		beneath IP can change according to the adopted convergence sublayers.
	This document provides the feasible IP Subnet model for each IP CS		This document provides the feasible IP Subnet model for each IP CS
	and Ethernet CS and specifies the problems in running IP protocols		and Ethernet CS and specifies the problems in running IP protocols
	for each case. This document also presents an overview of 802.16		for each case. This document also presents an overview of 802.16
	network characteristics specifically focusing on the convergence		network characteristics specifically focusing on the convergence
	sublayers and the common terminology to be used for the base		sublayers and the common terminology to be used for the base
	guideline while defining solution frameworks.		guideline while defining solution frameworks.
	2. Terminology		2. Terminology
	Subscriber Station (SS): An end-user equipment that provides		Subscriber Station (SS): An end-user equipment that provides
	connectivity to the 802.16 networks. It can be either fixed/nomadic		connectivity to the 802.16 networks. It can be either fixed/nomadic
	or mobile equipment. In mobile environment, SS represents the Mobile		or mobile equipment. In mobile environment, SS represents the Mobile
	Subscriber Station (MS) introduced in [IEEE802.16e].		Subscriber Station (MS) introduced in [IEEE802.16e].
	Base Station (BS): A generalized equipment sets providing		Base Station (BS): A generalized equipment sets that provides
	connectivity, management, and control between the subscriber station		connectivity, management, and control between the subscriber station
	and the 802.16 networks.		and the 802.16 networks.
	Access Router (AR): An entity that performs an IP routing function to		Access Router (AR): An entity that performs an IP routing function to
	provide IP connectivity for subscriber station (SS or MS).		provide IP connectivity for the subscriber station (SS or MS).
	Protocol Data Unit (PDU): This refers to the data format passed from		Protocol Data Unit (PDU): This refers to the data format passed from
	the lower edge of the 802.16 MAC to the 802.16 PHY, which typically		the lower edge of the 802.16 MAC to the 802.16 PHY, which typically
	contains Service Data Unit data after fragmentation, encryption, etc.		contains Service Data Unit data after fragmentation, encryption, etc.
	Service Data Unit (SDU): This refers to the data format passed to the		Service Data Unit (SDU): This refers to the data format passed to the
	upper edge of the 802.16 MAC		upper edge of the 802.16 MAC
	IP Subnet: Topological area that uses the same IP address prefix		IP Subnet: Topological area that uses the same IP address prefix
	where that prefix is not further subdivided except into individual		where that prefix is not further subdivided except into individual
	addresses as specified from [RFC4903].		addresses as specified from [RFC4903].
	Link: Topological area bounded by routers which decrement the IPv4		Link: Topological area bounded by routers which decrement the IPv4
	TTL or IPv6 Hop Limit when forwarding the packet as specified from		TTL or IPv6 Hop Limit when forwarding the packet as specified from
	[RFC4903].		[RFC4903].
	Transport Connection: The MAC layer connection in 802.16 between a		Transport Connection: The MAC layer connection in 802.16 between a SS
	SS(MS) and BS with a specific QoS attributes. Several types of		(MS) and BS with a specific QoS attributes. Several types of
	connections are defined and these include broadcast, unicast and		connections are defined and these include broadcast, unicast and
	multicast. Each transport connection is uniquely identified by a 16-		multicast. Each transport connection is uniquely identified by a 16-
	bit connection identifier (CID). A transport connection is a unique		bit connection identifier (CID). A transport connection is a unique
	connection intended for user traffic. The scope of the transport		connection intended for user traffic. The scope of the transport
	connection is between the SS(MS) and the BS.		connection is between the SS(MS) and the BS.
	Connection Identifier (CID): A 16-bit value that identifies a		Connection Identifier (CID): A 16-bit value that identifies a
	connection to equivalent peers in the 802.16 MAC of the SS(MS) and		connection to equivalent peers in the 802.16 MAC of the SS(MS) and
	BS.		BS.
	Ethernet CS: It means 802.3/Ethernet CS specific part of the Packet		Ethernet CS: The 802.3/Ethernet CS specific part of the Packet CS
	CS defined in 802.16 STD.		defined in [IEEE802.16].
	802.1Q CS: It means 802.1Q (VLAN) specific part of the Packet CS		802.1Q CS: The 802.1Q (VLAN) specific part of the Packet CS defined
	defined in 802.16 STD.		in [IEEE802.16].
	IP CS: It means IP specific subpart of the Packet CS defined in		IP CS: The IP specific subpart of the Packet CS defined in
	802.16 STD.		[IEEE802.16].
	IPv4 CS: It means IP specific subpart of the Packet CS, Classifier 1		IPv4 CS: The IP specific subpart of the Packet CS, Classifier 1
	(Packet, IPv4)		(Packet, IPv4)
	IPv6 CS: It means IP specific subpart of the Packet CS, Classifier 2		IPv6 CS: The IP specific subpart of the Packet CS, Classifier 2
	(Packet, IPv6).		(Packet, IPv6).
	3. Overview of the IEEE 802.16-2004 MAC layer		3. Overview of the IEEE 802.16 MAC layer
	802.16 [IEEE802.16] is point-to-point and connection-oriented at the		802.16 [IEEE802.16] is point-to-point and connection-oriented at the
	MAC, physically arranged in a point-to-multipoint structure with the		MAC, physically arranged in a point-to-multipoint structure with the
	BS terminating one end of each connection and an individual SS		BS terminating one end of each connection and an individual SS
	terminating the other end of each connection. Each node in the		terminating the other end of each connection. Each SS in the network
	network possesses a 48-bit MAC address (though in the Base Station		possesses a 48-bit MAC address. The BS possesses a 48-bit unique
	this 48-bit unique identifier is called "BSId"). The BS and SS learn		identifier called "BSId". The BS and SS learn each others' MAC
	each others' MAC Address/BSId during the SS's entry into the network.		Address/BSId during the SS's entry into the network. Additionally,
			the BS may possess a 48-bit MAC address, but this is only known to
			the SS if using the Ethernet CS.
	3.1. Transport Connections		3.1. Transport Connections
	User data traffic in both the BS-bound (uplink) and SS-bound		User data traffic in both the BS-bound (uplink) and SS-bound
	(downlink) directions is carried on unidirectional "transport		(downlink) directions is carried on unidirectional "transport
	connections". Each transport connection has a particular set of		connections". Each transport connection has a particular set of
	associated parameters indicating characteristics such as		associated parameters indicating characteristics such as
	cryptographic suite and quality-of-service.		cryptographic suite and quality-of-service.
	After successful entry of a SS to the 802.16 network, no data traffic		After successful entry of a SS to the 802.16 network, no data traffic
	is possible - as there are as yet no transport connections between		is possible as there are yet no transport connections between the BS
	the BS and SS. Transport connections are established by a 3-message		and the SS. Transport connections are established by a 3-message
	signaling sequence within the MAC layer (usually initiated by the		signaling sequence within the MAC layer (usually initiated by the
	BS).		BS).
	A downlink-direction transport connection is regarded as "multicast"		A downlink-direction transport connection is regarded as "multicast"
	if it has been made available (via MAC signaling) to more than one		if it has been made available (via MAC signaling) to more than one
	SS. Uplink-direction connections are always unicast.		SS. Uplink-direction connections are always unicast.
	3.2. 802.16 PDU format		3.2. 802.16 PDU format
	An 802.16 PDU (ie. the format that is transmitted over the airlink)		An 802.16 PDU (ie. the format that is transmitted over the airlink)
	skipping to change at page 6, line 15		skipping to change at page 6, line 17
	observe that there is no source or destination address present in the		observe that there is no source or destination address present in the
	raw 802.16 MAC header.		raw 802.16 MAC header.
	3.3. 802.16 Convergence Sublayer		3.3. 802.16 Convergence Sublayer
	The 802.16 convergence sublayer (CS) is the component of the MAC that		The 802.16 convergence sublayer (CS) is the component of the MAC that
	is responsible for mapping between the MAC service and the internal		is responsible for mapping between the MAC service and the internal
	connection oriented service of the MAC CPS (Common Part Sublayer),		connection oriented service of the MAC CPS (Common Part Sublayer),
	through classification and encapsulation. The classification process		through classification and encapsulation. The classification process
	assigns transmit-direction Service Data Units (originating from a		assigns transmit-direction Service Data Units (originating from a
	higher layer application - eg. an IP stack at the BS or SS) to a		higher layer application, e.g., an IP stack at the BS or SS) to a
	specific outbound transport connection. The convergence sublayer		specific outbound transport connection. The convergence sublayer
	maintains an ordered "classifier table". Each entry in the		maintains an ordered "classifier table". Each entry in the
	classifier table includes a classifier and a target CID. A		classifier table includes a classifier and a target CID. A
	classifier, in turn, consists of a conjunction of one or more		classifier, in turn, consists of a conjunction of one or more
	subclassifiers - where each subclassifier specifies a packet field		subclassifiers - where each subclassifier specifies a packet field
	(eg. the destination MAC address in an Ethernet frame, or the TOS		(eg. the destination MAC address in an Ethernet frame, or the TOS
	field of an IP datagram contained in an Ethernet frame) together with		field of an IP datagram contained in an Ethernet frame) together with
	a particular value or range of values for the field. To perform		a particular value or range of values for the field. To perform
	classification on an outbound Service Data Unit, the convergence		classification on an outbound Service Data Unit, the convergence
	sublayer proceeds from the first entry of the classifier table to the		sublayer proceeds from the first entry of the classifier table to the
	skipping to change at page 6, line 46		skipping to change at page 6, line 48
	o "The IP Specific Subpart" carries IP packets over a point-to-point		o "The IP Specific Subpart" carries IP packets over a point-to-point
	connection.		connection.
	o "The 802.3 Ethernet Specific Subpart" carries packets encoded in		o "The 802.3 Ethernet Specific Subpart" carries packets encoded in
	the 802.3/Ethernet packet format with 802.3 style headers.		the 802.3/Ethernet packet format with 802.3 style headers.
	o "The 802.1Q VLAN Specific Subpart" carries 802 style packets that		o "The 802.1Q VLAN Specific Subpart" carries 802 style packets that
	contain 802.1Q VLAN Tags.		contain 802.1Q VLAN Tags.
	Classifiers applied to connections at the time of connection		Classifiers applied to connections at the time of connection
	establishment further classifies and subdivides the nature of the		establishment further classifie and subdivide the nature of the
	traffic over a connection.		traffic over a connection.
	The classifications that apply to the Ethernet CS include packet over		The classifications that apply to the Ethernet CS include packet over
	the 802.3/Ethernet CS, IPv4 over the 802.3/Ethernet CS, IPv6 over the		the 802.3/Ethernet CS, IPv4 over the 802.3/Ethernet CS, IPv6 over the
	802.3/Ethernet CS, 802.3/Ethernet CS with ROHC header compression and		802.3/Ethernet CS, 802.3/Ethernet CS with ROHC header compression and
	802.3/Ethernet with ECRTP header compression.		802.3/Ethernet with ECRTP header compression.
	The classifications that apply to the 802.1Q/VLAN CS include IPv4		The classifications that apply to the 802.1Q/VLAN CS include IPv4
	over 802.1Q/VLAN and IPv6 over 802.1Q/VLAN.		over 802.1Q/VLAN and IPv6 over 802.1Q/VLAN.
	skipping to change at page 8, line 4		skipping to change at page 8, line 4
	The key issue when deploying IP over IEEE 802.16 network is how to		The key issue when deploying IP over IEEE 802.16 network is how to
	configure an IP Subnet over that link which is connection-oriented		configure an IP Subnet over that link which is connection-oriented
	and point-to-point in the MAC level. IP Subnet is a topological area		and point-to-point in the MAC level. IP Subnet is a topological area
	that uses the same IP address prefix where that prefix is not further		that uses the same IP address prefix where that prefix is not further
	subdivided except into individual addresses. [RFC4903] There are		subdivided except into individual addresses. [RFC4903] There are
	three different IP Subnet models [RFC4968] that are possible for		three different IP Subnet models [RFC4968] that are possible for
	802.16 network:		802.16 network:
	1) Point-to-point Link Model		1) Point-to-point Link Model
	2) Ethernet like Link Model		2) Ethernet-like Link Model
	3) Shared IPv6 Prefix Link Model		3) Shared IPv6 Prefix Link Model
	The specific problems and issues when adopting the above IP Subnet		The specific problems and issues when adopting the above IP Subnet
	models to the IEEE 802.16 network are like below:		models to the IEEE 802.16 network are as below:
	In the first point-to-point link model, each SS under a BS resides on		In the point-to-point link model, each SS under a BS resides on a
	the different IP Subnets. Therefore, only a certain SS and an AR		different IP Subnet. Therefore, only a certain SS and an AR exist
	exist under an IP Subnet and IP packets with destination address of		under an IP Subnet, and IP packets with destination address of link
	link local scope are delivered only within the point-to-point link		local scope are delivered only within the point-to-point link between
	between a SS and an AR. The PPP [RFC1661] has been widely used for		a SS and an AR. PPP [RFC1661] has been widely used for this kind of
	this kind of point-to-point link. However, the direct use of PPP is		point-to-point link. However, the direct use of PPP is not possible
	not possible on the 802.16 network because the 802.16 does not define		on the 802.16 network because 802.16 does not define a convergence
	a convergence sublayer which can encapsulate and decapsulate PPP		sublayer which can encapsulate and decapsulate PPP frames.
	frames. Therefore, there needs to be a mechanism to provide a point-		Therefore, there needs to be a mechanism to provide a point-to-point
	to-point link between a SS and an AR in case of IP CS. The other		link between a SS and an AR in case of IP CS. The other alternative
	alternative is to utilize the PPP over Ethernet by using the Ethernet		is to utilize PPP over Ethernet by using the Ethernet CS. However,
	CS. However, Ethernet CS assumes the upper layer's bridging		Ethernet CS assumes the upper layer's bridging functionality to
	functionality to realize the Ethernet like link model.		realize the Ethernet-like link model.
	In the second Ethernet like link model, all SSs under an AR reside on		In the Ethernet-like link model, all SSs under an AR reside on the
	the same IP Subnet. This also applies when SSs are connected with		same IP Subnet. This also applies when SSs are connected with
	different BSs. This Ethernet like link model assumes that underlying		different BSs. This Ethernet-like link model assumes that underlying
	link layer provides the equivalent functionality like Ethernet, for		link-layer provides the equivalent functionality like Ethernet, for
	example, native broadcast and multicast. It seems feasible to apply		example, native broadcast and multicast. It seems feasible to apply
	the 802.16's Ethernet CS to configure this link model. However, the		802.16's Ethernet CS to configure this link model. However, 802.16's
	802.16's MAC feature is still connection-oriented not providing		MAC feature is still connection-oriented, and does not provide
	multicast and broadcast connection for IP packet transfer. There		multicast and broadcast connection for IP packet transfer.
	needs mechanisms like IEEE 802.1D to realize multicast and broadcast		Therefore, we need a mechanism like IEEE 802.1D to realize multicast
	for Ethernet CS. Moreover, the frequent IP multicast and broadcast		and broadcast. Moreover, frequent IP multicast and broadcast
	signaling within the IP subnet like Ethernet needs to be avoided not		signaling should be avoided not to wake up sleep/idle [IEEE802.16e]
	to wake up sleep/idle [IEEE802.16e] SSs.		SSs.
	The last shared IPv6 prefix link model eventually results in multi-		The shared IPv6 prefix link model eventually results in multi-link
	link subnet problems [RFC4903]. In 802.16, BS assigns separate		subnet problems [RFC4903]. In 802.16, the BS assigns separate 802.16
	802.16 connections for SSs. Therefore, SSs are placed on the		connections for SSs. Therefore, SSs are placed on different links.
	different links. In this situation, distributing shared IPv6 prefix		In this situation, distributing shared IPv6 prefix for SSs which are
	for SSs which are placed on the different links causes the multi-link		placed on different links causes multi-link subnet problems. This
	subnet problems. This is valid for IP CS and even to the Ethernet CS		applies to IP CS and even to Ethernet CS if no bridging functionality
	if any bridging functionality is not implemented on top of BS or		is implemented on top of the BS or between the BS and the AR.
	between BS and AR.
	We identified the feasible IP Subnet models for IEEE 802.16 networks		We identified the feasible IP Subnet models for IEEE 802.16 networks
	depending on the convergence sublayers. At the current stage, only		depending on the convergence sublayers. At the current stage, only
	the IP CS and Ethernet CS of IEEE 802.16 are within the 16ng scope.		the IP CS and Ethernet CS of IEEE 802.16 are within the scope of
	Followings are the feasible IP Subnet models for each convergence		16ng. Following are the feasible IP Subnet models for each
	sublayer used.		convergence sublayer used.
	1. Point-to-Point Link model for IP CS.		1. Point-to-Point Link model for IP CS.
	2. Ethernet like Link Model for Ethernet CS.		2. Ethernet-like Link Model for Ethernet CS.
	According to the point-to-point feature of 802.16's MAC, the Point-		According to the point-to-point feature of the 802.16 MAC, the Point-
	to-Point link model is the feasible IP Subnet model for IP CS under		to-Point link model is the feasible IP Subnet model in the case of IP
	considering the multilink subnet problems. For the Ethernet CS, the		CS. For the Ethernet CS, the Ethernet-like link model is the
	Ethernet like link model is the feasible IP Subnet model. However,		feasible IP Subnet model. However, in this model unnecessary
	in this model unnecessary multicast and broadcast packets within an		multicast and broadcast packets within an IP Subnet should be
	IP Subnet should be minimized.		minimized.
	4.2. Point-to-Point Link model for IP CS: Problems		4.2. Point-to-Point Link model for IP CS: Problems
	- Address Resolution:		- Address Resolution:
	Address Resolution is the process by which IP nodes determine the		Address Resolution is the process by which IP nodes determine the
	link- layer address of a destination node on the same IP Subnet given		link- layer address of a destination node on the same IP Subnet given
	only the destination's IP address. In case of IPCS, the ARP cache or		only the destination's IP address. In the case of IPCS, the 802.16
	Neighbor cache as 802.16 MAC address is never used as part of the		MAC address is not used as part of the 802.16 frame so typical usage
	802.16 frame. Thus, performing the address resolution may be		of the ARP or Neighbor cache does not apply. Thus, performing the
	redundant in case of IPCS. For IPv4, blocking ARP needs to be		address resolution may be redundant in the case of IP CS. For IPv4,
	implemented by SS itself in an implementation specific fashion not to		ARP cannot be carried by the IP CS, so is not used either by the SS
	send the unnecessary broadcast (Ethernet) frames over the air. For		or by the BS. For IPv6, address resolution is the function of IP
	IPv6, address resolution is the function of IP layer and the IP		layer, and IP reachability state is maintained through neighbor
	reachability state is maintained through neighbor discovery packets.		discovery packets. Therefore, blocking neighbor discovery packets
	Therefore, blocking neighbor discovery packets would break the		would break the neighbor unreachability detection model.
	neighbor unreachability detection model.
	-Router Discovery:		-Router Discovery:
	BS needs to send the RA with separate IP prefix in unicast manner for		The BS needs to send the RA with separate IP prefix in unicast manner
	each SS explicitly to send periodic router advertisements in 802.16		for each SS explicitly to send periodic router advertisements in
	Networks.		802.16 Networks.
	- Prefix Assignment:		- Prefix Assignment:
	Separate IP prefix should be distributed for each SS to locate them		Separate IP prefix should be distributed for each SS to locate them
	on different IP Subnets. When a SS moves between BSs under the same		on different IP Subnets. When a SS moves between BSs under the same
	AR, the AR needs to redistribute the same IP Subnet prefix which the		AR, the AR needs to redistribute the same IP Subnet prefix which the
	SS used at the previous BS.		SS used at the previous BS.
	- Next-Hop:		- Next-Hop:
	SS's next-hop always needs to be the AR which provides the IP		SS's next-hop always needs to be the AR which provides the IP
	connectivity at that access network.		connectivity at that access network.
	- Neighbor Unreachability Detection (NUD):		- Neighbor Unreachability Detection (NUD):
	Because SS always see an AR as the next hop, the NUD is required only		Because the SS always sees an AR as the next hop, the NUD is required
	for that AR. Also the requirement of NUD may depend on the existence		only for that AR. Also the requirement of NUD may depend on the
	of a connection to the BS for that particular destination.		existence of a connection to the BS for that particular destination.
	- Address Autoconfiguration:		- Address Autoconfiguration:
	Because a unique prefix is assigned to each SS, the IP Subnet		Because a unique prefix is assigned to each SS, the IP Subnet
	consists of only one SS and an AR. Therefore, duplicate address		consists of only one SS and an AR. Therefore, duplicate address
	detection (DAD) is trivial.		detection (DAD) is trivial.
	4.3. Ethernet like Link model for Ethernet CS: Problems		4.3. Ethernet-like Link model for Ethernet CS: Problems
	- Address Resolution:		- Address Resolution:
	For Ethernet CS, sender needs to perform an address resolution to		For Ethernet CS, the sender needs to perform an address resolution to
	fill the destination Ethernet address field even though that address		fill the destination Ethernet address field even though that address
	is not used for transmitting an 802.16 frame on the air. That		is not used for transmitting an 802.16 frame on the air. That
	Ethernet destination address is used for a BS or bridge to decide		Ethernet destination address is used for a BS or bridge to decide
	where to forward that Ethernet frame after decapsulating the 802.16		where to forward that Ethernet frame after decapsulating the 802.16
	frame. When the destination's IP address has the same address prefix		frame. When the destination's IP address has the same address prefix
	with its own, the sender should set the Ethernet frame's destination		with its own, the sender should set the Ethernet frame's destination
	address as the destination itself. To acquire that address, the		address as the destination itself. To acquire that address, the
	address resolution should be performed throughout conventional		address resolution should be performed throughout conventional
	broadcast and multicast based ARP or NDP. However, if not filtered		broadcast and multicast based ARP or NDP. However, if not filtered
	(e.g., [RFC4541]), these multicast and broadcast packets result in		(e.g., [RFC4541]), these multicast and broadcast packets result in
	the problem of waking up the sleep/idle [IEEE802.16e] SSs.		the problem of waking up the sleep/idle [IEEE802.16e] SSs.
	- Router Discovery:		- Router Discovery:
	All SSs under the AR are located in the same broadcast domain in the		All SSs under the AR are located in the same broadcast domain in the
	Ethernet like link model. In this environment, sending periodic		Ethernet-like link model. In this environment, sending periodic
	Router Advertisements with the destination of all-nodes multicast		Router Advertisements with the destination of all-nodes multicast
	address results in the problem of waking up the sleep/idle		address results in the problem of waking up the sleep/idle
	[IEEE802.16e] SSs.		[IEEE802.16e] SSs.
	- Prefix Assignment:		- Prefix Assignment:
	Because the same IP prefix is shared with multiple SSs, an IP Subnet		Because the same IP prefix is shared with multiple SSs, an IP Subnet
	consists of multiple SSs and an AR. SS assumes that there exist on-		consists of multiple SSs and an AR. The SS assumes that there exist
	link neighbors and tries to resolve the L2 address for the on-link		on-link neighbors and tries to resolve the L2 address for the on-link
	prefixes. However, direct communication using link layer address		prefixes. However, direct communication using link-layer address
	between two SSs is not possible only with Ethernet CS without adding		between two SSs is not possible only with Ethernet CS without adding
	bridging functionality on top of BS or between BS and AR.		bridging functionality on top of the BS or between the BS and AR.
	- Next-Hop:		- Next-Hop:
	When Ethernet CS is used and the accompanying Ethernet capability		When Ethernet CS is used and the accompanying Ethernet capability
	emulation is implemented, the next-hop for the destination IP with		emulation is implemented, the next-hop for the destination IP with
	the same global prefix with the sender or link local address type		the same global prefix with the sender or link local address type
	should be the destination itself not an AR.		should be the destination itself not an AR.
	- Neighbor Unreachability Detection (NUD):		- Neighbor Unreachability Detection (NUD):
	All SSs under the same AR are all the neighbors. Therefore, the NUD		All SSs under the same AR are all the neighbors. Therefore, the NUD
	is required for all the SSs and AR.		is required for all the SSs and AR.
	- Address Autoconfiguration:		- Address Autoconfiguration:
	The duplicate address detection (DAD) should be performed among		Duplicate address detection (DAD) should be performed among multiple
	multiple SSs and an AR which are using the same IP prefix. The		SSs and an AR which are using the same IP prefix. The previous
	previous multicast based DAD cause the problem of waking up the		multicast-based DAD causes the problem of waking up the sleep/idle
	sleep/idle [IEEE802.16e] SSs.		[IEEE802.16e] SSs.
	4.4. IP over IEEE 802.16 Goals		4.4. IP over IEEE 802.16 Goals
	The following are the goals in no particular order that point at		The following are the goals in no particular order that point at
	relevant work to be done in IETF.		relevant work to be done in IETF.
	Goal #1. Define the way to provide the point-to-point link model for		Goal #1. Define the way to provide the point-to-point link model for
	IP CS.		IP CS.
	Goal #2. Reduce the power consumption caused by waking up sleep/idle		Goal #2. Reduce the power consumption caused by waking up sleep/idle
	[IEEE802.16e] terminals for Ethernet like link model.		[IEEE802.16e] terminals for Ethernet-like link model.
	Goal #3. Do not cause multilink subnet problems.		Goal #3. Avoid multilink subnet problems.
	Goal #4. Provide the applicability of the previous security works		Goal #4. Allow applicability of security schemes such as SeND
	like SEND [RFC3971].		[RFC3971].
	Goal #5. Do not introduce any new security threats.		Goal #5. Do not introduce any new security threats.
	5. IANA Considerations		5. IANA Considerations
	This document does not require any actions from IANA.		This document does not require any actions from IANA.
	6. Security Considerations		6. Security Considerations
	This documents describes the problem statement and goals for IP over		This documents describes the problem statement and goals for IP over
	802.16 networks and does not introduce any new security threats.		802.16 networks and does not introduce any new security threats. The
			802.16 link-layer employs cryptographic security mechanisms as
			specified in [IEEE802.16][IEEE802.16e].
	7. Acknowledgment		7. Contributors
			This document is a joint effort of the problem statement team of the
			16ng WG. The team members include Junghoon Jee, Syam Madanapalli,
			Jeff Mandin, Gabriel Montenegro, Soohong Daniel Park and Maximilian
			Riegel.
			The problem statment team members can be reached at:
			Junghoon Jee, jhjee@etri.re.kr
			Syam Madanapalli, smadanapalli@gmail.com
			Jeff Mandin, jeff@streetwaves-networks.com
			Gabriel Montenegro, g_e_montenegro@yahoo.com
			Soohong Daniel Park, soohong.park@samsung.com
			Maximilian Riegel, maximilian.riegel@nsn.com
			8. Acknowledgment
	The authors would like to express special thank to David Johnston for		The authors would like to express special thank to David Johnston for
	amending the section 4, "Overview of the IEEE 802.16-2006 MAC layer"		his help with section 4, "Overview of the IEEE 802.16 MAC layer", and
	and carefully reviewing the entire document and also to Phil Roberts		for carefully reviewing the entire document, and also to Phil Roberts
	for suggesting the reorganization of the document depending on the		for suggesting the reorganization of the document depending on the
	baseline IP subnet models.		baseline IP subnet models.
	The authors also would like to express thank to Jari Arkko, HeeYoung		The authors also would like to thank Jari Arkko, HeeYoung Jung,
	Jung, Myung-Ki Shin, Eun-Kyoung Paik, Jaesun Cha and KWISF (Korea		Myung-Ki Shin, Eun-Kyoung Paik, Jaesun Cha and KWISF (Korea Wireless
	Wireless Internet Standardization Forum) for their comments and		Internet Standardization Forum) for their comments and contributions.
	contributions.
	8. References		9. References
	8.1. Normative References		9.1. Normative References
	[RFC1661] Simpson, W., "The Point-to-Point Protocol (PPP)", STD 51,		[RFC1661] Simpson, W., "The Point-to-Point Protocol (PPP)", STD 51,
	RFC 1661, July 1994.		RFC 1661, July 1994.
	[RFC3971] Arkko, J., Kempf, J., Zill, B., and P. Nikander, "SEcure		[RFC3971] Arkko, J., Kempf, J., Zill, B., and P. Nikander, "SEcure
	Neighbor Discovery (SEND)", RFC 3971, March 2005.		Neighbor Discovery (SEND)", RFC 3971, March 2005.
	8.2. Informative References		9.2. Informative References
	[IEEE802.16]		[IEEE802.16]
	IEEE Std 802.16-2004, "IEEE Standard for Local and		IEEE Std 802.16-2004, "IEEE Standard for Local and
	metropolitan area networks, Part 16: Air Interface for		metropolitan area networks, Part 16: Air Interface for
	Fixed Broadband Wireless Access Systems", October 2004.		Fixed Broadband Wireless Access Systems", October 2004.
	[IEEE802.16e]		[IEEE802.16e]
	IEEE Std 802.16e, "IEEE standard for Local and		IEEE Std 802.16e, "IEEE standard for Local and
	metropolitan area networks, Part 16:Air Interface for		metropolitan area networks, Part 16:Air Interface for
	fixed and Mobile broadband wireless access systems",		fixed and Mobile broadband wireless access systems",
	skipping to change at page 13, line 9		skipping to change at page 13, line 33
	[RFC4903] Thaler, D., "Multi-Link Subnet Issues", RFC 4903,		[RFC4903] Thaler, D., "Multi-Link Subnet Issues", RFC 4903,
	June 2007.		June 2007.
	[RFC4968] Madanapalli, S., "Analysis of IPv6 Link Models for 802.16		[RFC4968] Madanapalli, S., "Analysis of IPv6 Link Models for 802.16
	Based Networks", RFC 4968, August 2007.		Based Networks", RFC 4968, August 2007.
	Authors' Addresses		Authors' Addresses
	Junghoon Jee		Junghoon Jee
	ETRI		ETRI
			161 Gajeong-dong Yuseong-gu
			Daejeon 305-350
			Korea
	Email: jhjee@etri.re.kr		Email: jhjee@etri.re.kr
	Syam Madanapalli		Syam Madanapalli
	LogicaCMG		Ordyn Technologies
	Email: smadanapalli@gmail.com		Email: smadanapalli@gmail.com
	Jeff Mandin		Jeff Mandin
	Runcom		Runcom
	Email: jeff@streetwaves-networks.com		Email: jeff@streetwaves-networks.com
	gabriel_montenegro_2000@yahoo.com
	Microsoft
	Email: gabriel_montenegro_2000@yahoo.com
	Soohong Daniel Park
	Samsung Electronics
	Email: soohong.park@samsung.com
	Max Riegel
	Nokia Siemens Networks
	Email: maximilian.riegel@nsn.com
	Full Copyright Statement		Full Copyright Statement
	Copyright (C) The IETF Trust (2007).		Copyright (C) The IETF Trust (2007).
	This document is subject to the rights, licenses and restrictions		This document is subject to the rights, licenses and restrictions
	contained in BCP 78, and except as set forth therein, the authors		contained in BCP 78, and except as set forth therein, the authors
	retain all their rights.		retain all their rights.
	This document and the information contained herein are provided on an		This document and the information contained herein are provided on an
	"AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS		"AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS
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