2006-01-11
Project
219546116
IEEE 802.21 Media Independent Handover Services
<http://www.ieee802.org/21/>
Title
21-06-0492-01-0000-GenRefModel.doc
Date
Submitted
January, 2006
Source(s)
Andrea Francini, Peretz Feder, Ulises
Olvera-Hernandez,
Lucent Technologies
francini@lucent.com, pfeder@lucent.com
ulises.olvera-hernandez@interdigital.com
Re:
P802-21-D00-04.pdf
Abstract
Revision proposal for Sections 5.5, 5.5.1, 5.5.2, and 5.5.3 (General MIH Reference Model
and IEEE 802 MIH Reference Models).
Purpose
Replace text in current draft.
Notice
Release
Patent
Policy
This document has been prepared to assist the IEEE 802.21 Working Group. It is offered as a basis for
discussion and is not binding on the contributing individual(s) or organization(s). The material in this
document is subject to change in form and content after further study. The contributor(s) reserve(s) the right
to add, amend or withdraw material contained herein.
The contributor grants a free, irrevocable license to the IEEE to incorporate material contained in this
contribution, and any modifications thereof, in the creation of an IEEE Standards publication; to copyright in
the IEEE’s name any IEEE Standards publication even though it may include portions of this contribution;
and at the IEEE’s sole discretion to permit others to reproduce in whole or in part the resulting IEEE
Standards publication. The contributor also acknowledges and accepts that this contribution may be made
public by IEEE 802.21.
The contributor is familiar with IEEE patent policy, as outlined in Section 6.3 of the IEEE-SA Standards
Board Operations Manual <http://standards.ieee.org/guides/opman/sect6.html#6.3> and in Understanding
Patent Issues During IEEE Standards Development <http://standards.ieee.org/board/pat/guide.html>.
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5.5 MIH Reference Models for Access Networks
The messaging exchanges between peer MIH Function instances, in particular the type of transport that
they use, are sensitive to several factors, such as the nature of the network nodes that contain the peer
MIH Function instances (whether or not one of the two is a Mobile Node or a PoA), the nature of the
access network (whether IEEE 802 or 3G cellular), and the availability of MIH capabilities at the PoA.
Figure 4 presents a summary of the types of relationship that may exist between the MIH Function and
other functional components in the same network node, and between the MIH Function and a peer MIH
Function instance residing in a different network node.
Access Agnostic Core
MIH Function in MIH
Network
Entity
MIH over Higher
Layer Transport
Media
Media
Independent
Independent
Handover
HandoverUser
User
Client
Station
MIH over Higher
Layer Transport
ES/
CS/
IS
Media Independent
Handover Function
Media Independent Handover
Function
ES/
CS/
IS
ES
ES
LLC/CS
CS
3GPP/
3GPP2
Interface
LLC/CS
CS
IS
IS
MIH Function in MIH
Network
Entity
MAC
PHY
MAC
PHY
MGMT
802 Interface
MGMT
MIH over L2
Transport
802 PoA
3GPP/3GPP2 PoA
Figure 4 Types of MIH Function relationship (option 1)
The General MIH Reference Model in Figure 5 enables a simple representation of the broad variety of
MIH Function relationships shown in Figure 4. In the Model, a mobility-management protocol stack is
logically identified within each network node that includes an MIH Function instance. The abstraction
provided makes it easy to isolate and represent the MIH relationships with all pre-existing functional
entities within the same network node. Such relationships are both internal (with functional entities that
share with the MIH function the logical inclusion in the mobility-management protocol) and external (with
functional entities that belong to other planes.
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Figure 5 illustrates the placement of the MIH Function and its SAPs within the mobility stack and its
interaction with the transport layers and network management plane.
MIH_SME_SAP
MIH_SAP
Configuration of MIH Function instance
from network/element management
station (GET, SET, TRAP, ...)
Upper Layers
MIES, MICS, and MIIS exchanges with
local upper layers
MIH_SAP
Network Manag.
MIH_SME_SAP
Plane
MIH
Function
MIH_NET
SAP
Transport
Interface
(to remote MIH)
MIH_NET_SAP
MIH_LINK_SAP
MIES, MICS, and MIIS exchanges with
remote MIH Function
MIH_LINK_SAP
Lower Layers
MIES, MICS, and MIIS exchanges with
local lower layers
Figure 5—General MIH SAP Reference Model
All exchanges between the MIH Function and other functional entities occur through service primitives,
grouped in Service Access Points (SAPs). Each SAP identifies an interface with a distinct functional entity
within the same network node.
The technology-agnostic General MIH SAP Reference Model includes the following four SAPs:
MIH_SAP: Media-independent interface with the upper layers of the mobility-management protocol stack.
MIH_LINK_SAP: Generic name for the media-dependent interface with the lower layers of the local node
protocol stacks.
MIH_NET_SAP: Generic name for the media-dependent interface with the transport elements, which
supports the exchange of MIH information and messages with remote MIH Function instances. In IEEE
802 networks, the MIH_NET_SAP typically maps onto a technology-specific link-layer transport SAP and a
common higher-layer transport interface. In 3G cellular networks, the MIH_NET_SAP typically maps onto
the common higher-layer transport interface. For upper layer transport (>L2), MIH_NET-SAP maps to the
basic socket APIs (bind(), connect(), sendmsg() or others) functions described in RFC-3493 and
designated here as the upper transport layers SAP.
MIH_SME_SAP: Media-independent interface with the management system that controls the local node
network element.
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The General MIH SAP Reference Model works as a template for the definition of the technology-specific
reference models. In those models, the media-independent SAPs (MIH_SAP and MIH_SME_SAP) always
maintain the same names and sets of primitives. Conversely, the media-dependent SAPs
(MIH_LINK_SAP and MIH_NET_SAP) assume media-specific names and sets of primitives, often reusing
names and primitives that already exist in the respective pre-existing lower-layer SAPs. The
MIH_LINK_SAP and MIH_NET_SAP never appear in the technology-specific reference models with their
generic names.
The inclusion of media-independent SAPs in the General MIH SAP Reference Model enables the
specification of a single, homogeneous set of service primitives across all link-layer technologies. Then, in
the technology-specific reference models, the general service primitives map onto functionally identical
service primitives, which are found in the pre-existing technology-specific SAPs and/or newly defined in
recommended extensions of those SAPs.
The following table provides the specific mapping of the SAP depicted in the general MIH Reference
Model to the specific technologies. The following sections describe this mapping.
General MIH Ref. Model
MIH_SME_SAP
MIH_SAP
MIH_Link_SAP
802.3
Not Applicable
MIH_SAP
LSAP
802.11
MIH_SME_SAP
MIH_SAP
MLME_SAP
MIH_NET_SAP for layer 2
MIH_NET_SAP for layer 3
LSAP
Socket APIs
LSAP
Socket APIs
802.16
M_SAP
MIH_SAP
C-SAP
M-SAP
Eth_CS_SAP/GPCS_SAP/C-SAP
Socket APIs
5.5.1 MIH SAP Reference Model for 802.3
The logical placement of the MIH Function in the 802.3 protocol stack is shown in Figure 6.
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Layer 3 Mobility Protocol (L3MP), Higher-Layer Mobility
Protocol, Handover Policy, Transport, Applications
802.21
Scope
MIH_SAP
Media Independent
Handover (MIH) Function
MIH Event Service
MIH Command Service
MIH Information Service
LSAP
Logical Link Control (LLC)
or other MAC client
MAC
PHY
Figure 6—Logical Placement of the MIH Function in the IEEE 802.3 protocol stack
Figure 7 shows the instantiation of the General MIH Reference Model when the access link complies with
the IEEE 802.3 standard.
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Upper Layers
MIH_SAP
MIH
Function
LSAP[L2]
NET-SAP[L3]
Transport
Interface
(to remote MIH)
LSAP
LLC
(Lower Layers)
Figure 7—MIH SAP Reference Model for IEEE 802.3
In the 802.3 reference model, the Logical Link Control (LLC) layer is the immediate MIH counterpart in the
lower layers of the stack.
The pre-existing LLC SAP (LSAP) instantiates the MIH_LINK_SAP of the General MIH Reference Model:
the MIH Function uses the LSAP to exchange information with the control portion of LLC for mobilitymanagement purposes. The LSAP also instantiates the link-layer portion of the generic MIH_NET_SAP
for the transport of MIH messages over L2. The MIH Function interface that instantiates the higher-layer
portion of the MIH_NET_SAP are the basic socket APIs (bind(), connect(), sendmsg(), others) functions
described in RFC-3493 and designated here as the network SAP interface.
As there is no Network Plane in the 802.3 wireline model mapping to this plane is not applicable.
5.5.2 MIH SAP Reference Model for 802.11
The logical placement of the MIH Function in the 802.11 protocol stack for stations and access points is
shown in Figure 8.
Similarly to 802.3, the LLC SAP (LSAP) defines the interface of the MIH Function with the 802.11 data
plane and can encapsulate MIH messages in data frames. However, since 802.11 does not currently
support Class 1 data frames, MIH messages can be transported over the 802.11 data plane only after the
Mobile Node has associated with the 802.11 access point. Before the association between Mobile Node
and access point takes place, the L2 transport of MIH messages can rely on 802.11 management frames
from the 802.11 management plane (MLME). The MIH_MLME_SAP defines the interface between the
MIH Function and the MLME.
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Layer 3 Mobility Protocol (L3MP), Higher-Layer Mobility
Protocol, Handover Policy, Transport, Applications
802.21
Scope
MIH_SAP
Media Independent
Handover (MIH) Function
MIH_SME_SAP
MIH Event Service
MIH Command Service
MIH Information Service
SME
LSAP
MLME_SAP
Logical Link Control
(LLC)
MLME_SAP
MLME
MAC_SAP
MAC
PHY_SAP
MLME_PLME_SAP
PHY
PLME
PLME_SAP
Figure 8—Logical Placement of the MIH Function in the IEEE 802.11 Protocol Stack
Figure 9 shows the instantiation of the General MIH Reference Model when the access link complies with
the IEEE 802.11 standard.
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Upper Layers
MIH_SAP
Network/Element
Manag. Plane
MIH_SME_SAP
MIH
Function
MLME_SAPxx[L2]
LSAP [L2]
NET-SAP[L3]
Transport
Interface
(to remote MIH)
MLME_SAP
MLME
(Lower Layers)
Figure 9— MIH SAP Reference Model for IEEE 802.11
Since the MAC Layer Management Entity (MLME) is the immediate MIH counterpart in the lower layers of
the 802.11 mobility-management, the MLME_SAP instantiates the MIH_LINK_SAP in the MIH Reference
Model for 802.11.
The MLME_SAP and the pre-existing LLC SAP (LSAP) instantiate the link-layer portion of the generic
MIH_NET_SAP for the transport of MIH messages over L2, respectively before and after the association
of the Mobile Node with the 802.11 access point takes place. The MIH Function interface that instantiates
the higher-layer portion of the MIH_NET_SAP are the basic socket APIs (bind(), connect(), sendmsg(),
others) functions described in RFC-3493 and designated here as the network SAP interface.
5.5.3 MIH SAP Reference Model for 802.16
The logical placement of the MIH Function in the 802.16 protocol stack is shown in Figure 10.
The MIH Function and the Network Control and Management System (NCMS) share the C_SAP and
M_SAP for access to the mobility-management services of the Mobility Control Entity and Management
Entity in the 802.16 Management Plane.
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The mechanisms for the direct encapsulation of MIH frames into 802.16 data frames may take multiple
forms. The Service-Specific Convergence Sublayer instances currently available in the 802.16 standard
and WiMAX only enable the encapsulation of IP packets and Ethernet frames. The only option available
for L2 transport would be to first encapsulate the MIH messages into Ethernet frames with an MIH
Ethertype value, and then mandate the adoption of Ethernet CS for 802.16 connections that carry the MIH
messages. This approach limits both the efficiency of the L2 transport of MIH messages (since it imposes
the addition of full Ethernet overhead – at least 18 bytes – to the MIH frame) and the availability of L2
transport capabilities for MIH (since Ethernet CS is not ubiquitous).
Alternatively, a solution that enables better efficiency and easier accessibility of L2 transport capabilities
could become available with the possible standardization of the Generic Packet Convergence Sublayer
(GPCS) recently proposed within 802.16g. With GPCS a more efficient LLC/SNAP encapsulation (8 bytes
overhead) could create the needed room for the MIH Ethertype in 802.16 frames.
Layer 3 Mobility Protocol (L3MP), Higher-Layer Mobility
Protocol, Handover Policy, Transport, Applications
MIH_SAP
802.21
Scope
NCMS
Media Independent
Handover (MIH) Function
MIH Event Service
MIH Command Service
MIH Information Service
CS_SAP
Service-Specific Convergence Sublayer (CS)
C_SAP
MAC_SAP
MAC Common Part Sublayer (MAC CPS)
Management Plane
Security Sublayer
M_SAP
PHY_SAP
Physical Layer (PHY)
Figure 10—Logical Placement of the MIH Function in the IEEE 802.16 Protocol Stack
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Upper Layers
MIH_SAP
Network/Element
Manag. Plane
M_SAP
GPCS/Eth_CS_SAP [L2]
NET_SAP[L3]
MIH
Function
Transport
Interface
(to remote MIH)
M_SAP
C_SAP
ME, CE
(Lower Layers)
Figure 11—MIH SAP Reference Model for IEEE 802.16
Figure 11 shows the instantiation of the General MIH SAP Reference Model when the access link
complies with the IEEE 802.16 standard.
Since the Control Entity (CE) and Management Entity (ME) are the immediate MIH counterparts in the
lower layers of the 802.16 mobility-management, the C_SAP and M_SAP instantiate the MIH_LINK_SAP
in the MIH Reference Model for 802.16.
The Eth_CS_SAP or GPCS_SAP instantiate the link-layer portion of the generic MIH_NET_SAP for the
transport of MIH messages over L2. The MIH Function interface that instantiates the higher-layer portion
of the MIH_NET_SAP are the basic socket APIs (bind(), connect(), sendmsg(), others) functions
described in RFC-3493 and designated here as the network SAP interface.
5.5.4 MIH Peer to Peer Communication
MIH peer to peer communication might be exchange over either a higher layer transport or a L2 transport.
The MIH Protocol Data Unit that is delivered to the MIH function is the same regardless of the chosen
transport. The following figure illustrates the delivery of an MIH PDU over a higher layer transport.
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Adapter
Adapter
IETF
IETF MIH-Packet
Exchange of
MIH-Frame as
defined by IEEE
L3 Transport
Exchange of
IETF MIH-Packet as
defined by IETF
IETF
IETF MIH-Packet
NET-SAP
NET-SAP
IEEE 802.21
MIH-Frame
IEEE 802.21
MIH-Frame
Peer 1
Peer 2
Exchange of
MIH-Frame as
defined by IEEE
Figure 12
Transport over L2 is technology specific and over L3 or above is through the basic socket APIs (bind(),
connect(), sendmsg(), others) functions described in RFC-3493 and designated in the generic model as
the NET-SAP.
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