draft-ietf-seamoby-mobility-terminology-03.txt   draft-ietf-seamoby-mobility-terminology-04.txt 
Internet Engineering Task Force J. Manner (ed.) Internet Engineering Task Force J. Manner (ed.)
Internet-Draft M. Kojo (ed.) Internet-Draft M. Kojo (ed.)
Expires: October, 2003 University of elsinki Expires: October, 2003 University of Helsinki
April, 2003 April, 2003
Mobility Related Terminology Mobility Related Terminology
<draft-ietf-seamoby-mobility-terminology-03.txt> <draft-ietf-seamoby-mobility-terminology-04.txt>
Status of this Memo Status of this Memo
This document is a working group document of the Seamoby Working This document is a working group document of the Seamoby Working
Group. Group.
Distribution of this memo is unlimited. Distribution of this memo is unlimited.
This document is an Internet-Draft and is in full conformance with This document is an Internet-Draft and is in full conformance with
all provisions of Section 10 of RFC2026. Internet-Drafts are working all provisions of Section 10 of RFC2026. Internet-Drafts are working
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Abstract Abstract
There is a need for common definitions of terminology in the work to There is a need for common definitions of terminology in the work to
be done around IP mobility. This memo defines terms for mobility be done around IP mobility. This memo defines terms for mobility
related terminology. It is intended as a living document for use by related terminology. It is intended as a living document for use by
the Seamoby Working Group in Seamoby drafts and in WG discussions, the Seamoby Working Group in Seamoby drafts and in WG discussions,
but not limited in scope to the terms needed by the Seamoby Working but not limited in scope to the terms needed by the Seamoby Working
Group. Other working groups dealing with mobility may take advantage Group. Other working groups dealing with mobility may take advantage
of this terminology. of this terminology.
Changes from -02
- Updated the terminology related to mobile networks
Changes from -01
- Added security terminology
- Miscellaneous small refinements of definitions
Changes from -00
- Added definition for Routing Proxy
- Added basic terminology about mobile networks
- Added Link-Layer Trigger from FMIPv6
- Edited the CAR terminology section
- Added definitions for MPR, CoA, BU
- Changed the definition of Home Address
- Added a mobile network into Figure 1
- Edited the Network Components section
Table of Contents Table of Contents
1 Introduction ................................................. 2 1 Introduction ................................................. 2
2 General Terms ................................................ 3 2 General Terms ................................................ 3
3 Mobile Access Networks and Mobile Networks ................... 8 3 Mobile Access Networks and Mobile Networks ................... 8
4 Handover Terminology ......................................... 13 4 Handover Terminology ......................................... 12
4.1 Scope of Handover .......................................... 14 4.1 Scope of Handover .......................................... 13
4.2 Handover Control ........................................... 15 4.2 Handover Control ........................................... 14
4.3 Simultaneous connectivity to Access Routers ................ 16 4.3 Simultaneous connectivity to Access Routers ................ 16
4.4 Performance and Functional Aspects ......................... 17 4.4 Performance and Functional Aspects ......................... 16
4.5 Micro Diversity, Macro Diversity, and IP Diversity ......... 18 4.5 Micro Diversity, Macro Diversity, and IP Diversity ......... 17
4.6 Paging, and Mobile Node States and Modes ................... 18 4.6 Paging, and Mobile Node States and Modes ................... 18
4.7 Context Transfer ........................................... 20 4.7 Context Transfer ........................................... 19
4.8 Candidate Access Router Discovery .......................... 21 4.8 Candidate Access Router Discovery .......................... 20
4.9 User, Personal and Host Mobility ........................... 21 4.9 User, Personal and Host Mobility ........................... 20
5 Specific Terminology for Mobile Ad-Hoc Networking ............ 23 5 Specific Terminology for Mobile Ad-Hoc Networking ............ 22
6 Security-related Terminology ................................. 24 6 Security-related Terminology ................................. 23
7 Security Considerations ...................................... 25 7 Security Considerations ...................................... 24
8 Contributors ................................................. 25 8 Contributors ................................................. 24
9 Acknowledgement .............................................. 25 9 Change log ................................................... 25
10 References .................................................. 26 10 Acknowledgement ............................................. 25
11 Author's Addresses .......................................... 27 11 Informative References ...................................... 25
12 Appendix A - Examples ....................................... 29 12 Author's Addresses .......................................... 26
13 Appendix B - Index of Terms ................................. 31 13 Appendix A - Examples ....................................... 29
14 Appendix B - Index of Terms ................................. 31
1. Introduction 1. Introduction
This document presents terminology to be used for documents and This document presents terminology to be used for documents and
discussions within the Seamoby Working Group. Other mobility related discussions within the Seamoby Working Group. Other mobility related
working groups could like take advantage of this terminology, in working groups could take advantage of this terminology, in order to
order to create a common terminology for the area of mobility in IP create a common terminology for the area of mobility in IP networks.
networks. These groups would include MIP, MANET, ROHC and NEMO. These groups would include MIP, MANET, ROHC and NEMO.
Some terms and their definitions that are not directly related to the Some terms and their definitions that are not directly related to the
IP world are included for the purpose of harmonizing the terminology, IP world are included for the purpose of harmonizing the terminology.
for example, 'Access Point' and 'base station' refer to the same For example, 'Access Point' and 'base station' refer to the same
component, from the point of view of IP, but 'Access Router' has a component, from the point of view of IP, but 'Access Router' has a
very different meaning. The presented terminology may also, it is very different meaning. The presented terminology may also, it is
hoped, be adequate to cover mobile ad-hoc networks. hoped, be adequate to cover mobile ad-hoc networks.
The proposed terminology is not meant to assert any new terminology. The proposed terminology is not meant to assert any new terminology.
Rather the authors would welcome discussion on more exact definitions Rather the authors would welcome discussion on more exact definitions
as well as missing or unnecessary terms. This work is a as well as missing or unnecessary terms. This work is a
collaborative enterprise between people from many different collaborative enterprise between people from many different
engineering backgrounds and so already presents a first step in engineering backgrounds and so already presents a first step in
harmonizing the terminology. harmonizing the terminology.
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The terminology in this draft is divided into several sections. The terminology in this draft is divided into several sections.
First, there is a list of terms for general use and mobile access First, there is a list of terms for general use and mobile access
networks followed by terms related to handovers, and finally some networks followed by terms related to handovers, and finally some
terms used within the MANET and NEMO working group. terms used within the MANET and NEMO working group.
2. General Terms 2. General Terms
Bandwidth Bandwidth
The total capacity of a link to carry information (typically The total capacity of a link to carry information (typically
bits). bits) per unit time.
Bandwidth Utilization Bandwidth Utilization
The actual amount of information delivered over a link, expressed The actual rate of information transfer achieved over a link,
as a percent of the available bandwidth on that link. expressed as a percent of the available bandwidth on that link.
Beacon Beacon
A control message broadcast by a node (especially, a base A control message broadcast by a node (especially, a base
station) informing all the other nodes in its neighborhood of the station) informing all the other nodes in its neighborhood of the
continuing presence of the broadcasting node, possibly along with continuing presence of the broadcasting node, possibly along with
additional status or configuration information. additional status or configuration information.
Binding update (BU) Binding update (BU)
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A subdivision of the physical medium allowing possibly shared A subdivision of the physical medium allowing possibly shared
independent uses of the medium. Channels may be made available independent uses of the medium. Channels may be made available
by subdividing the medium into distinct time slots, or distinct by subdividing the medium into distinct time slots, or distinct
spectral bands, or decorrelated coding sequences. spectral bands, or decorrelated coding sequences.
Channel Access Protocol Channel Access Protocol
A protocol for mediating access to, and possibly allocation of, A protocol for mediating access to, and possibly allocation of,
the various channels available within the physical communications the various channels available within the physical communications
medium. Nodes participating in the channel access protocol can medium. Nodes participating in the channel access protocol agree
communicate only when they have uncontested access to the medium, to communicate only when they have uncontested access to one of
so that there will be no interference. the channels, so that there will be no interference.
Control Message Control Message
Information passed between two or more network nodes for Information passed between two or more network nodes for
maintaining protocol state, which may be unrelated to any maintaining protocol state, which may be unrelated to any
specific application. specific application.
Distance Vector Distance Vector
A style of routing protocol in which, for each desired A style of routing protocol in which, for each desired
destination, a node maintains information about the distance to destination, a node maintains information about the distance to
that destination, and a vector (next hop) towards that that destination, and a vector (next hop) towards that
destination. destination.
Fairness Fairness
A property of channel access protocols whereby a medium is made A property of channel access protocols whereby a medium is made
fairly equal to all eligible nodes on the link. Fairness does fairly available to all eligible nodes on the link. Fairness
not strictly imply equality, especially in cases where nodes are does not strictly imply equality, especially in cases where nodes
given link access according to unequal priority or are given link access according to unequal priority or
classification. classification.
Flooding Flooding
The process of delivering data or control messages to every node The process of delivering data or control messages to every node
within the network under consideration. within the network under consideration.
Foreign subnet prefix Foreign subnet prefix
A bit string that consists of some number of initial bits of an A bit string that consists of some number of initial bits of an
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all broadcast messages that it receives. The message must be new all broadcast messages that it receives. The message must be new
and the time-to-live field of the message must be greater than and the time-to-live field of the message must be greater than
one. Multipoint relaying is a technique to reduce the number of one. Multipoint relaying is a technique to reduce the number of
redundant re-transmissions while diffusing a broadcast message in redundant re-transmissions while diffusing a broadcast message in
the network. the network.
Neighbor Neighbor
A "neighbor" is any other node to which data may be propagated A "neighbor" is any other node to which data may be propagated
directly over the communications medium without relying the directly over the communications medium without relying the
assistance of any other forwarding node assistance of any other forwarding node.
Neighborhood Neighborhood
All the nodes which can receive data on the same link from one All the nodes which can receive data on the same link from one
node whenever it transmits data. node whenever it transmits data.
Next Hop Next Hop
A neighbor which has been selected to forward packets along the A neighbor which has been selected to forward packets along the
way to a particular destination. way to a particular destination.
Payload Payload
The actual data within a packet, not including network protocol The actual data within a packet, not including network protocol
headers which were not inserted by an application. Note, that headers which were not inserted by an application. Note that
payloads are different between layers: user data is the payload payloads are different between layers: user data is the payload
of TCP, which are the payload of IP, which three are the payload of TCP, which are the payload of IP, which three are the payload
of link layer protocols etc. Thus, it is important to identify of link layer protocols etc. Thus, it is important to identify
the scope when talking about payloads. the scope when talking about payloads.
Prefix Prefix
A bit string that consists of some number of initial bits of an A bit string that consists of some number of initial bits of an
address. address.
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(possibly directed) "edges." (possibly directed) "edges."
Triggered Update Triggered Update
An unsolicited route update transmitted by an router along a path An unsolicited route update transmitted by an router along a path
to a destination. to a destination.
3. Mobile Access Networks and Mobile Networks 3. Mobile Access Networks and Mobile Networks
In order to support host mobility a set of nodes towards the network In order to support host mobility a set of nodes towards the network
edge may need to have specific functions. Such a set of nodes form a edge may need to have specific functions. Such a set of nodes forms a
mobile access network that may or may not be part of the global mobile access network that may or may not be part of the global
Internet. The Figure 1 presents two examples of such access network Internet. Figure 1 presents two examples of such access network
topologies. The figure depicts a reference architecture which topologies. The figure depicts a reference architecture which
illustrates an IP network with components defined in this section. illustrates an IP network with components defined in this section.
We intend to define the concept of the Access Network (AN) which may We intend to define the concept of the Access Network (AN) which may
also support enhanced mobility. It is possible that to support also support enhanced mobility. It is possible that to support
routing and QoS for mobile nodes, existing routing protocols (i.e., routing and QoS for mobile nodes, existing routing protocols (e.g.,
OSPF or other standard IGPs) may not be appropriate to maintain OSPF or other standard IGPs) may not be appropriate to maintain
forwarding information for these mobile nodes as they change their forwarding information for these mobile nodes as they change their
points of attachment to the Access Network. These new functions are points of attachment to the Access Network. These new functions are
implemented in routers with additional capability. We can distinguish implemented in routers with additional capability. We can distinguish
three types of Access Network components: Access Routers (AR) which three types of Access Network components: Access Routers (AR) which
handle the last hop to the mobile, typically over a wireless link; handle the last hop to the mobile, typically over a wireless link;
Access Network Gateways (ANG) which form the boundary on the fixed Access Network Gateways (ANG) which form the boundary on the fixed
network side and shield the fixed network from the specialized network side and shield the fixed network from the specialized
routing protocols; and (optionally) other internal Access Network routing protocols; and (optionally) other internal Access Network
Routers which may also be needed in some cases to support the Routers which may also be needed in some cases to support the
protocols. The Access Network consists of the equipment needed to protocols. The Access Network consists of the equipment needed to
support this specialized routing, i.e. AR/ANG/ANR. AR and ANG may be support this specialized routing, i.e. AR or ANG. AR and ANG may be
the same physical nodes. the same physical nodes.
In addition, we present a few basic terms on mobile networks, that In addition, we present a few basic terms on mobile networks, that
is, mobile network, mobile router (MR), and mobile network node is, mobile network, mobile router (MR), and mobile network node
(MNN). A more thorough discussion on mobile networks can be found in (MNN). More terminology for discussing mobile networks can be found
the working group documents of the NEMO Working Group. in [15]. A more thorough discussion on mobile networks can be found
in the working group documents of the NEMO Working Group.
Note: this reference architecture is not well suited for people Note: this reference architecture is not well suited for people
dealing with MANETs. dealing with MANETs.
--- ------ ------- | --- ------ ------- |
--- | <--> | | -------| AR | -------------------| | | --- | <--> | | -------| AR | -------------------| | |
| |--[] --- /------ \ /| ANG |--| | |--[] --- /------ \ /| ANG |--|
--- AP / \ / | | | --- AP / \ / | | |
MH / \ / ------- | MH / \ / ------- |
(+wireless ___ / ------- | (+wireless ___ / ------- |
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the network, or when such a change is attempted. The access the network, or when such a change is attempted. The access
network may provide features to minimize the interruption to network may provide features to minimize the interruption to
sessions in progress. sessions in progress.
There are different types of handover classified according to There are different types of handover classified according to
different aspects involved in the handover. Some of this different aspects involved in the handover. Some of this
terminology follows the description of [4]. terminology follows the description of [4].
4.1. Scope of Handover 4.1. Scope of Handover
Note: the definitions of horizontal and vertical handover are Note that the definitions of horizontal and vertical handover are
different than the ones commonly used today. These definitions try to different than the ones commonly used today. These definitions try to
look at the handover from the IP layer's point of view; the IP layer look at the handover from the IP layer's point of view; the IP layer
works with network interfaces, rather than specific technologies used works with network interfaces, rather than specific technologies used
by those interfaces. by those interfaces.
Layer 2 Handover Layer 2 Handover
When a MN changes APs (or some other aspect of the radio channel) When a MN changes APs (or some other aspect of the radio channel)
connected to the same AR's interface then a layer 2 handover connected to the same AR's interface then a layer 2 handover
occurs. This type of handover is transparent to the routing at occurs. This type of handover is transparent to the routing at
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the MN is the one that makes the initial decision to initiate the the MN is the one that makes the initial decision to initiate the
handover. handover.
Network-initiated Handover Network-initiated Handover
the network makes the initial decision to initiate the handover. the network makes the initial decision to initiate the handover.
A handover is also one of the following two types (b): A handover is also one of the following two types (b):
Mobile-controlled Handover (MCHO) Mobile-controlled Handover (MCHO)
the MN has the primary control over the handover process. the MN has the primary control over the handover process.
Network-controlled Handover (NCHO) Network-controlled Handover (NCHO)
the network has the primary control over the handover process. the network has the primary control over the handover process.
A handover may also be either of these three types (c): A handover is also either of these three types (c):
Mobile-assisted handover Mobile-assisted handover
information and measurement from the MN are used by the AR to information and measurement from the MN are used by the AR to
decide on the execution of a handover. decide on the execution of a handover.
Network-assisted handover Network-assisted handover
a handover where the AN collects information that can be used by a handover where the AN collects information that can be used by
the MN in a handover decision. the MN in a handover decision.
Unassisted handover Unassisted handover
a handover where no assistance is provided by the MN or the AR to a handover where no assistance is provided by the MN or the AR to
each other. each other.
Note that it is possible that the MN and the AR both do
measurements and decide on the handover.
A handover is also one of the following two types (d): A handover is also one of the following two types (d):
Backward handover Backward handover
a handover either initiated by the OAR, or where the MN initiates a handover either initiated by the OAR, or where the MN initiates
a handover via the OAR. a handover via the OAR.
Forward handover Forward handover
a handover either initiated by the NAR, or where the MN initiates a handover either initiated by the NAR, or where the MN initiates
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Throughput Throughput
The amount of data from a source to a destination processed by The amount of data from a source to a destination processed by
the protocol for which throughput is to be measured for instance, the protocol for which throughput is to be measured for instance,
IP, TCP, or the MAC protocol. The throughput differs between IP, TCP, or the MAC protocol. The throughput differs between
protocol layers. protocol layers.
Goodput Goodput
The total bandwidth used, less the volume of control messages and The total bandwidth used, less the volume of control messages,
protocol overhead from the data packets. protocol overhead from the data packets, and packets dropped due
to CRC errors.
Pathloss Pathloss
A reduction in signal strength caused by traversing the physical A reduction in signal strength caused by traversing the physical
medium constituting the link. medium constituting the link.
Hidden-terminal problem Hidden-terminal problem
The problem whereby a transmitting node can fail in its attempt The problem whereby a transmitting node can fail in its attempt
to transmit data because of destructive interference which is to transmit data because of destructive interference which is
only detectable at the receiving node, not the transmitting node. only detectable at the receiving node, not the transmitting node.
Exposed terminal problem Exposed terminal problem
The problem whereby a transmitting node prevents another node The problem whereby a transmitting node prevents another node
from transmitting although it could have safely transmitted to from transmitting although it could have safely transmitted to
anyone else but that node. anyone else but that node.
4.5. Micro Diversity, Macro Diversity, and IP Diversity 4.5. Micro Diversity, Macro Diversity, and IP Diversity
Certain air interfaces (e.g. UTRAN FDD mode) require or at least Certain air interfaces (e.g. the Universal Mobile Telephone System
support macro diversity combining. Essentially, this refers to the (UMTS) Terrestial Radio Access Network (UTRAN) running in Frequency
fact that a single MN is able to send and receive over two Division Duplex (FDD) mode) require or at least support macro
independent radio channels ('diversity branches') at the same time; diversity combining. Essentially, this refers to the fact that a
the information received over different branches is compared and that single MN is able to send and receive over two independent radio
from the better branch passed to the upper layers. This can be used channels ('diversity branches') at the same time; the information
both to improve overall performance, and to provide a seamless type received over different branches is compared and that from the better
of handover at layer 2, since a new branch can be added before the branch passed to the upper layers. This can be used both to improve
old is deleted. See also [6]. overall performance, and to provide a seamless type of handover at
layer 2, since a new branch can be added before the old is deleted.
See also [6].
It is necessary to differentiate between combining/diversity that It is necessary to differentiate between combining/diversity that
occurs at the physical and radio link layers, where the relevant unit occurs at the physical and radio link layers, where the relevant unit
of data is the radio frame, and that which occurs at layer 3, the of data is the radio frame, and that which occurs at layer 3, the
network layer, where what is considered is the IP packet itself. network layer, where what is considered is the IP packet itself.
In the following definitions micro- and macro diversity refer to In the following definitions micro- and macro diversity refer to
protocol layers below the network layer, and IP diversity refers to protocol layers below the network layer, and IP diversity refers to
the network layer. the network layer.
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Macro diversity Macro diversity
Duplicating or combining actions taking place over multiple APs, Duplicating or combining actions taking place over multiple APs,
possibly attached to different ARs. This may require support possibly attached to different ARs. This may require support
from the network layer to move the radio frames between the base from the network layer to move the radio frames between the base
stations and a central combining point. stations and a central combining point.
IP diversity IP diversity
the splitting and combining of packets at the IP level. The splitting and combining of packets at the IP level.
4.6. Paging, and Mobile Node States and Modes 4.6. Paging, and Mobile Node States and Modes
Mobile systems may employ the use of MN states in order to operate Mobile systems may employ the use of MN states in order to operate
more efficiently without degrading the performance of the system. The more efficiently without degrading the performance of the system. The
term term 'mode' is also common and means the same as 'state'.
A MN is always in one of the following three states: A MN is always in one of the following three states:
Active State Active State
when the AN knows the MN's SAR and the MN can send and receive IP When the AN knows the MN's SAR and the MN can send and receive IP
packets. The AL may not be active, but the radio layer is able packets. The AL may not be active, but the radio layer is able
to establish one without assistance from the network layer. The to establish one without assistance from the network layer. The
MN has an IP address assigned. MN has an IP address assigned.
Dormant State Dormant State
A state in which the mobile restricts its ability to receive A state in which the mobile restricts its ability to receive
normal IP traffic by reducing its monitoring of radio channels. normal IP traffic by reducing its monitoring of radio channels.
The AN knows the MH's Paging Area, but the MH has no SAR and so The AN knows the MH's Paging Area, but the MH has no SAR and so
packets cannot be delivered to the MH without the AN initiating packets cannot be delivered to the MH without the AN initiating
paging. paging.
Time-slotted Dormant Mode Time-slotted Dormant Mode
A dormant mode implementation in which the mobile alternates A dormant mode implementation in which the mobile alternates
between periods of not listening for any radio traffic and between periods of not listening for any radio traffic and
listening for traffic. Time-slotted dormant mode listening for traffic. Time-slotted dormant mode implementations
implementations are typically synchronized with the network so are typically synchronized with the network so the network can
the network can deliver traffic to the mobile during listening deliver traffic to the mobile during listening periods.
periods.
Inactive State Inactive State
the MH is in neither the Active nor Dormant State. The host is no the MH is in neither the Active nor Dormant State. The host is no
longer listening for any packets, not even periodically, and not longer listening for any packets, not even periodically, and not
sending packets. The host may be in a powered off state, it may sending packets. The host may be in a powered off state, it may
have shut down all interfaces to drastically conserve power, or have shut down all interfaces to drastically conserve power, or
it may be out of range of a radio access point. The MN does not it may be out of range of a radio access point. The MN does not
necessarily have an IP access address from the AN. necessarily have an IP access address from the AN.
Note: in fact, as well as the MN being in one of these three states, Note: in fact, as well as the MN being in one of these three states,
the AN also stores which state it believes the MN is in. Normally the AN also stores which state it believes the MN is in. Normally
these are consistent; the definitions above assume so. these are consistent; the definitions above assume so.
Here are some additional definitions for paging, taking into account Here are some additional definitions for paging, taking into account
the above state definitions. the above state definitions.
Paging Paging
a procedure initiated by the Access Network to move an Idle MN A procedure initiated by the Access Network to move an Idle MN
into the Active State. As a result of paging, the MN establishes into the Active State. As a result of paging, the MN establishes
a SAR and the IP routes are set up. a SAR and the IP routes are set up.
Location updating Location updating
a procedure initiated by the MN, by which it informs the AN that A procedure initiated by the MN, by which it informs the AN that
it has moved into a new paging area. it has moved into a new paging area.
Paging Area Paging Area
A part of the Access Network, typically containing a number of A part of the Access Network, typically containing a number of
ARs/APs, which corresponds to some geographical area. The AN ARs/APs, which corresponds to some geographical area. The AN
keeps and updates a list of all the Idle MNs present in the area. keeps and updates a list of all the Idle MNs present in the area.
If the MN is within the radio coverage of the area it will be If the MN is within the radio coverage of the area it will be
able to receive paging messages sent within that Paging Area. able to receive paging messages sent within that Paging Area.
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A characteristic of the service offered by an AR that may be of A characteristic of the service offered by an AR that may be of
interest to an MN when the AR is being considered as a handoff interest to an MN when the AR is being considered as a handoff
candidate. candidate.
Candidate AR (CAR) Candidate AR (CAR)
An AR to which MN has a choice of performing IP-level handoff. An AR to which MN has a choice of performing IP-level handoff.
This means that MN has the right radio interface to connect to an This means that MN has the right radio interface to connect to an
AP that is served by this AR, as well as the coverage of this AR AP that is served by this AR, as well as the coverage of this AR
overlaps with that of the AR to which MN is currently attached overlaps with that of the AR to which MN is currently attached.
to.
Target AR (TAR) Target AR (TAR)
An AR with which the procedures for the MN's IP-level handoff are An AR with which the procedures for the MN's IP-level handoff are
initiated. TAR is selected after running a TAR Selection initiated. TAR is selected after running a TAR Selection
Algorithm that takes into account the capabilities of CARs, Algorithm that takes into account the capabilities of CARs,
preferences of MN and any local policies. preferences of MN and any local policies.
4.9. User, Personal and Host Mobility 4.9. User, Personal and Host Mobility
Different sorts of mobility management may be required of a mobile Different sorts of mobility management may be required of a mobile
system. We can differentiate between user, personal and host system. We can differentiate between user, personal, host and
mobility. network mobility.
User mobility User mobility
refers to the ability of a user to access services from different refers to the ability of a user to access services from different
physical hosts. This usually means, the user has an account on physical hosts. This usually means the user has an account on
these different hosts or that a host does not restrict users from these different hosts or that a host does not restrict users from
using the host to access services. using the host to access services.
Personal mobility Personal mobility
complements user mobility with the ability to track the user's complements user mobility with the ability to track the user's
location and provide the user's current location to allow location and provide the user's current location to allow
sessions to be initiated by and towards the user by anyone on any sessions to be initiated by and towards the user by anyone on any
other network. Personal mobility is also concerned with enabling other network. Personal mobility is also concerned with enabling
associated security, billing and service subscription associated security, billing and service subscription
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functions depending on what the current level of service is being functions depending on what the current level of service is being
provided; in particular, support for host mobility usually provided; in particular, support for host mobility usually
implies active and idle modes of operation, depending on whether implies active and idle modes of operation, depending on whether
the host has any current sessions or not. Access Network the host has any current sessions or not. Access Network
procedures are required to keep track of the current point of procedures are required to keep track of the current point of
attachment of all the MNs or establish it at will. Accurate attachment of all the MNs or establish it at will. Accurate
location and routing procedures are required in order to maintain location and routing procedures are required in order to maintain
the integrity of the communication. Host mobility is often the integrity of the communication. Host mobility is often
called 'terminal mobility'. called 'terminal mobility'.
Two subcategories of "Host mobility" can be identified: Network mobility
Network mobility occurs when an entire network changes its point
of attachment to the Internet and, thus, its reachability in the
topology, which is referred to as a mobile network.
Two subcategories of mobility can be identified withing either host
mobility and network mobility:
Global mobility Global mobility
Same as Macro mobility. Same as Macro mobility.
Local mobility Local mobility
Same as Micro mobility. Same as Micro mobility.
Macro mobility Macro mobility
skipping to change at page 22, line 52 skipping to change at page 22, line 14
Micro mobility Micro mobility
Mobility over a small area. Usually this means mobility within Mobility over a small area. Usually this means mobility within
an IP domain with an emphasis on support for active mode using an IP domain with an emphasis on support for active mode using
handover, although it may include idle mode procedures also. handover, although it may include idle mode procedures also.
Micro-mobility protocols exploit the locality of movement by Micro-mobility protocols exploit the locality of movement by
confining movement related changes and signalling to the access confining movement related changes and signalling to the access
network. network.
Network mobility
Network mobility occurs when an entire network changes its point
of attachment to the Internet and, thus, its reachability in the
topology, which is referred to as a mobile network.
Local Mobility Management Local Mobility Management
Local Mobility Management (LMM) is a generic term for protocols Local Mobility Management (LMM) is a generic term for protocols
dealing with IP mobility management confined within the access dealing with IP mobility management confined within the access
network. LMM messages itself are not routed outside the access network. LMM messages are not routed outside the access network,
network, although, a handover may trigger Mobile IP messages to although a handover may trigger Mobile IP messages to be sent to
be sent to correspondent nodes and home agents. correspondent nodes and home agents.
5. Specific Terminology for Mobile Ad-Hoc Networking 5. Specific Terminology for Mobile Ad-Hoc Networking
Cluster Cluster
A group of nodes located within close physical proximity, A group of nodes located within close physical proximity,
typically all within range of one another, which can be grouped typically all within range of one another, which can be grouped
together for the purpose of limiting the production and together for the purpose of limiting the production and
propogation of routing information. propogation of routing information.
skipping to change at page 25, line 44 skipping to change at page 25, line 5
o Nikos Georganopoulos, King's College London o Nikos Georganopoulos, King's College London
o Markku Kojo and Jukka Manner, University of Helsinki, Finland. o Markku Kojo and Jukka Manner, University of Helsinki, Finland.
Since revision -02 of the document draft-manner-seamoby-terms-02.txt, Since revision -02 of the document draft-manner-seamoby-terms-02.txt,
Charles Perkins has given as input terminology related to ad-hoc Charles Perkins has given as input terminology related to ad-hoc
networks. networks.
Thierry Ernst has provided the terminology for discussing mobile Thierry Ernst has provided the terminology for discussing mobile
networks. networks.
9. Acknowledgement 9. Change log
Changes from -03
- Added comments from Randy Presuhn and Thierry Ernst
Changes from -02
- Updated the terminology related to mobile networks
Changes from -01
- Added security terminology
- Miscellaneous small refinements of definitions
Changes from -00
- Added definition for Routing Proxy
- Added basic terminology about mobile networks
- Added Link-Layer Trigger from FMIPv6
- Edited the CAR terminology section
- Added definitions for MPR, CoA, BU
- Changed the definition of Home Address
- Added a mobile network into Figure 1
- Edited the Network Components section
10. Acknowledgement
This work has been partially performed in the framework of the IST This work has been partially performed in the framework of the IST
project IST-2000-28584 MIND, which is partly funded by the European project IST-2000-28584 MIND, which is partly funded by the European
Union. The authors would like to acknowledge the help of their Union. Some of the authors would like to acknowledge the help of
colleagues in preparing this document. their colleagues in preparing this document.
Randy Presuhn did a very thorough and helpful review of the -02
version of the terminology.
Some definitions of terminology have been adapted from [1], [7], [3], Some definitions of terminology have been adapted from [1], [7], [3],
[2], [4], [9], [10], [11] and [12]. [2], [4], [9], [10], [11] and [12].
10. References 11. Informative References
[1] D. Blair, A. Tweedly, M. Thomas, J. Trostle, and [1] Blair, D., Tweedly, A., Thomas, M., Trostle, J. and
M. Ramalho. Realtime Mobile IPv6 Framework (work in Ramalho, M., "Realtime Mobile IPv6 Framework", Work in
progress). Internet Draft, Internet Engineering Task Force. Progress.
draft-blair-rt-mobileipv6-seamoby-00.txt, November 2000.
[2] P. Calhoun, G. Montenegro, and C. Perkins. Mobile IP [2] Calhoun, P., Montenegro, G. and Perkins, C., "Mobile IP
Regionalized Tunnel Management (work in progress). Internet Regionalized Tunnel Management", Work in Progress.
Draft, Internet Engineering Task Force, November 1998.
[3] S. Deering and R. Hinden. Internet Protocol, Version 6 (IPv6) [3] Deering, S. and Hinden, R., "Internet Protocol, Version 6
Specification. Request for Comments 2460, Internet Engineering (IPv6) Specification". RFC 2460, December 1998.
Task Force, December 1998.
[4] G. Dommety (ed.). Fast Handovers for Mobile IPv6 (work [4] Dommety, G. (ed.), "Fast Handovers for Mobile IPv6", Work in
in progress). draft-ietf-mobileip-fast-mipv6-06.txt, Progress.
March, 2003.
[5] Yavatkar et al. A Framework for Policy-based Admission [5] Yavatkar, R., Pendarakis, D. and Guerin, R., "A Framework for
Control. Request for Comments 2753, Internet Engineering Task Policy-based Admission Control". RFC 2753, January 2000.
Force, January 2000.
[6] J. Kempf, P. McCann, and P. Roberts. IP Mobility and the CDMA [6] Kempf, J., McCann, P. and Roberts, P., "IP Mobility and the
Radio Access Network: Applicability Statement for Soft Handoff CDMA Radio Access Network: Applicability Statement for Soft
(work in progress). Internet Draft, Handoff", Work in Progress.
draft-kempf-cdma-appl-00.txt, July 2000.
[7] J. Kempf (ed.). Problem Description: Reasons For Doing [7] Kempf, J. (ed.), "Problem Description: Reasons For Doing
Context Transfers Between Nodes in an IP Access Network. Context Transfers Between Nodes in an IP Access Network".
RFC 3374, Internet Engineering Task Force, September, 2002. RFC 3374, September 2002.
[8] R. Pandya. Emerging Mobile and Personal Communication Systems. [8] Pandya, R., "Emerging Mobile and Personal Communication
IEEE Communications Magazine, 33:44--52, June 1995. Systems". IEEE Communications Magazine, 33:44--52, June 1995.
[9] R. Ramjee, T. La Porta, S. Thuel, K. Varadhan, and [9] Ramjee, R., La Porta, T., Thuel, S., Varadhan, K. and
L. Salgarelli. IP micro-mobility support using HAWAII (work in Salgarelli, L., "IP micro-mobility support using HAWAII", Work
progress). Internet Draft, Internet Engineering Task Force, in Progress.
June 1999.
[10] D. Trossen, G. Krishnamurthi, H. Chaskar, J. Kempf, "Issues in [10] Trossen, D., Krishnamurthi, G., Chaskar, H. and Kempf, J.,
candidate access router discovery for seamless IP-level "Issues in candidate access router discovery for seamless
handoffs. Internet Draft (work in progress), IP-level handoffs", Work in Progress.
draft-ietf-seamoby-cardiscovery-issues-04.txt, October 2002.
[11] David B. Johnson, Charles E. Perkins, Jari Arkko, "Mobility [11] Johnson, D., Perkins, D. and Arkko, J., "Mobility
Support in IPv6". Internet Draft, Support in IPv6", Work in Progress.
draft-ietf-mobileip-ipv6-21.txt (work in progress), February
2003.
[12] Charles Perkins (ed.), "IP Mobility Support for IPv4". Request [12] Perkins, C. (ed.), "IP Mobility Support for IPv4". RFC 3344,
for Comments 3344, August 2002. August 2002.
[13] Charles Perkins, Pat Calhoun, Jayshree Bharatia, "Mobile [13] Perkins, C., Calhoun, P. and Bharatia, J., "Mobile
IPv4 Challenge/Response Extensions (revised)". Internet Draft, IPv4 Challenge/Response Extensions (revised)", Work in
December, 2002 (draft-ietf-mobileip-rfc3012bis-04.txt). Progress.
[14] Charles Perkins, Pat Calhoun, "AAA Registration Keys for Mobile [14] Perkins, C. and Calhoun, P., "AAA Registration Keys for Mobile
IP". Internet Draft, March 2003, IP", Work in Progress.
(draft-ietf-mobileip-aaa-key-11.txt).
11. Author's Addresses [15] Ernst, T. and Lach, H., "Network Mobility Support
Terminology", Work in Progress.
12. Author's Addresses
Questions about this document may be directed to: Questions about this document may be directed to:
Jukka Manner Jukka Manner
Department of Computer Science Department of Computer Science
University of Helsinki University of Helsinki
P.O. Box 26 (Teollisuuskatu 23) P.O. Box 26 (Teollisuuskatu 23)
FIN-00014 HELSINKI FIN-00014 HELSINKI
Finland Finland
skipping to change at page 28, line 43 skipping to change at page 28, line 21
E-Mail: robert.hancock@roke.co.uk E-Mail: robert.hancock@roke.co.uk
Nikos Georganopoulos Nikos Georganopoulos
King's College London King's College London
Strand Strand
London WC2R 2LS London WC2R 2LS
United Kingdom United Kingdom
Voice: +44-20-78482889 Voice: +44-20-78482889
Fax: +44-20-78482664 Fax: +44-20-78482664
E-Mail: nikolaos.georganopoulos@kcl.ac.uk) E-Mail: nikolaos.georganopoulos@kcl.ac.uk
12. Appendix A - Examples 13. Appendix A - Examples
This appendix provides examples for the terminology presented. This appendix provides examples for the terminology presented.
A.1. Mobility A.1. Mobility
Host mobility is logically independent of user mobility, although in Host mobility is logically independent of user mobility, although in
real networks, at least the address management functions are often real networks, at least the address management functions are often
required to initially attach the host to the network. In addition, required to initially attach the host to the network. In addition,
if the network wishes to determine whether access is authorized (and if the network wishes to determine whether access is authorized (and
if so, who to charge for it), then this may be tied to the identity if so, who to charge for it), then this may be tied to the identity
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mobility is based on the use of a unique personal identity (i.e., mobility is based on the use of a unique personal identity (i.e.,
personal number)." personal number)."
Roaming, in its original (GSM) sense, is the ability of a user to Roaming, in its original (GSM) sense, is the ability of a user to
connect to the networks owned by operators other than the one having connect to the networks owned by operators other than the one having
a direct formal relationship with the user. More recently (e.g., in a direct formal relationship with the user. More recently (e.g., in
data networks and UMTS) it also refers providing user-customized data networks and UMTS) it also refers providing user-customized
services in foreign networks (e.g., QoS profiles for specific services in foreign networks (e.g., QoS profiles for specific
applications). applications).
HAWAII, Cellular IP, Regional Registration and EMA are examples of HAWAII, Cellular IP, Regional Registration and Edge Mobility
micro mobility schemes, with the assumption that Mobile IP is used Architecture (EMA) are examples of micro mobility schemes, with the
for macro mobility. assumption that Mobile IP is used for macro mobility.
WLAN technologies such as IEEE 802.11 typically support aspects of Wireless LAN technologies such as IEEE 802.11 typically support
user and host mobility in a minimal way. User mobility procedures aspects of user and host mobility in a minimal way. User mobility
(for access control and so on) are defined only over the air procedures (for access control and so on) are defined only over the
interface (and the way these are handled within the network is not air interface (and the way these are handled within the network is
further defined). not further defined).
PLMNs (GSM/UMTS) typically have extensive support for both user and Public Land Mobile Networks (GSM/UMTS) typically have extensive
host mobility. Complete sets of protocols (both over the air and on support for both user and host mobility. Complete sets of protocols
the network side) are provided for user mobility, including (both over the air and on the network side) are provided for user
customized service provision. Handover for host mobility is also mobility, including customized service provision. Handover for host
supported, both within access networks, and also within the GSM/UMTS mobility is also supported, both within access networks, and also
core network for mobility between access networks of the same within the GSM/UMTS core network for mobility between access networks
operator. of the same operator.
A.2. Handovers A.2. Handovers
A hard handover is required where a MN is not able to receive or send A hard handover is required where a MN is not able to receive or send
traffic from/to two APs simultaneously. In order to move the traffic traffic from/to two APs simultaneously. In order to move the traffic
channel from the old to the new access point the MN abruptly changes channel from the old to the new access point the MN abruptly changes
the frequency/timeslot/code on which it is transmitting and listening the frequency/timeslot/code on which it is transmitting and listening
to new values associated with a new access point. Thus, the handover to new values associated with a new access point. Thus, the handover
is a break-before-make handover. is a break-before-make handover.
A good example of hard handover is GSM where the mobile listens for A good example of hard handover is GSM where the mobile listens for
new base stations, reports back to the network the signal strength new base stations, reports back to the network the signal strength
and identity of the new base station(s) heard. When the old base and identity of the new base station(s) heard. When the old base
station decides that a handover is required it instructs the new base station decides that a handover is required it instructs the new base
station to set up resources and, when confirmed, instructs the mobile station to set up resources and, when confirmed, instructs the mobile
to switch to a new frequency and time slot. This sort of hand over to switch to a new frequency and time slot. This sort of hand over
is called hard, mobile assisted, network initiated and backward is called hard, mobile assisted, network initiated and backward
(meaning that the old base station is responsible for handling the (meaning that the old base station is responsible for handling the
change-over). change-over).
In a TDMA system, such as GSM, the hard hand over is delayed until In a Time-Division Multiple Access (TDMA) system, such as GSM, the
the mobile has moved well within the coverage of the new base hard hand over is delayed until the mobile has moved well within the
station. If the handover threshold was set to the point where the coverage of the new base station. If the handover threshold was set
new base station signal exceeded the old then there would be a very to the point where the new base station signal exceeded the old then
large number of handovers as the mobile moved through the region there would be a very large number of handovers as the mobile moved
between the cells and radio signals fluctuated, this would create a through the region between the cells and radio signals fluctuated,
large signalling traffic. To avoid this a large hysteresis is set, this would create a large signalling traffic. To avoid this a large
i.e. the new base station must be (say) 10dB stronger for handover hysteresis is set, i.e. the new base station must be (say) 10dB
to occur. If the same was done in W-CDMA then the mobile would be stronger for handover to occur. If the same was done in Wideband
Carrier Division Multiple Access (W-CDMA) then the mobile would be
transmitting a powerful signal to the old base station and creating transmitting a powerful signal to the old base station and creating
interference for other users, since in CDMA everyone else's interference for other users, since in CDMA everyone else's
transmissions are seen as noise, thus reducing capacity. To avoid transmissions are seen as noise, thus reducing capacity. To avoid
this soft handover is used, giving an estimated doubling in capacity. this soft handover is used, giving an estimated doubling in capacity.
Support for soft handover (in a single mode terminal) is Support for soft handover (in a single mode terminal) is
characteristic of radio interfaces which also require macro diversity characteristic of radio interfaces which also require macro diversity
for interference limitation but the two concepts are logically for interference limitation but the two concepts are logically
independent. independent.
A good example of soft handover is the UTRAN FDD mode. W-CDMA is A good example of soft handover is the UTRAN FDD mode. W-CDMA is
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context to be fulfilled is that the new AP can accommodate the new context to be fulfilled is that the new AP can accommodate the new
mobile, for example, the new GSM cell can serve the incoming phone. mobile, for example, the new GSM cell can serve the incoming phone.
Lately, the notion of Context-aware Handovers has been enlarged by, Lately, the notion of Context-aware Handovers has been enlarged by,
for example, QoS-aware handovers, meaning that the handover is for example, QoS-aware handovers, meaning that the handover is
governed by the need to support the QoS-context of the moving mobile governed by the need to support the QoS-context of the moving mobile
in order to keep the service level assured to the user of the MN. in order to keep the service level assured to the user of the MN.
A.3. Diversity combining A.3. Diversity combining
In the case of UMTS it is radio frames that are duplicated at some In the case of UMTS it is radio frames that are duplicated at some
point in the network (the serving RNC) and sent to a number of point in the network, at the serving Radio Network Controller (RNC),
basestations and, possibly via other (drift) RNCs. The combining and sent to a number of basestations and, possibly via other (drift)
that takes place at the serving RNC in the uplink direction is RNCs. The combining that takes place at the serving RNC in the uplink
typically based on some simple quality comparison of the various direction is typically based on some simple quality comparison of the
received frames, which implies that the various copies of these various received frames, which implies that the various copies of
frames must contain identical upper layer information. The serving these frames must contain identical upper layer information. The
RNC also has to do buffering data frames to take account of the serving RNC also has to do buffering data frames to take account of
differing time of flight from each basestation to the RNC. the differing time of flight from each basestation to the RNC.
A.4. Miscellaneous A.4. Miscellaneous
In a GPRS/UMTS system the Access Network Gateway node could be the In a GPRS/UMTS system the Access Network Gateway node could be the
GGSN component. The ANG can provide support for mobility of hosts, GGSN component. The ANG can provide support for mobility of hosts,
admission control, policy enforcement, and Foreign Agent admission control, policy enforcement, and Foreign Agent
functionality [9]. functionality [9].
When presenting a mobile network topology, APs and ARs are usually When presenting a mobile network topology, APs and ARs are usually
pictured as separate components (see Figure 1. This is the case with pictured as separate components (see Figure 1). This is the case
GSM/GPRS/UMTS presentations, for example. From the IP point of view with GSM/GPRS/UMTS presentations, for example. From the IP point of
APs are not directly visible. An AP should only be seen from the view APs are not directly visible. An AP should only be seen from
MN's or AR's IP layer as a link (interface) connecting MNs to the AR. the MN's or AR's IP layer as a link (interface) connecting MNs to the
AR.
When the mobile moves through the network, depending on the mobility When the mobile moves through the network, depending on the mobility
mechanism, the OAR will forward packets destined to the old MNs mechanism, the OAR will forward packets destined to the old MNs
address to the SAR which currently serves the MN. At the same time address to the SAR which currently serves the MN. At the same time
the handover mechanism may be studying CARs to find the best NAR the handover mechanism may be studying CARs to find the best NAR
where the MN will be handed next. where the MN will be handed next.
13. Appendix B - Index of Terms 14. Appendix B - Index of Terms
<TBA when terminology finalized> <TBA when terminology finalized>
Full Copyright Statement Full Copyright Statement
Copyright (C) The Internet Society (2001). All Rights Reserved. Copyright (C) The Internet Society (2001). All Rights Reserved.
This document and translations of it may be copied and furnished to This document and translations of it may be copied and furnished to
others, and derivative works that comment on or otherwise explain it others, and derivative works that comment on or otherwise explain it
or assist in its implementation may be prepared, copied, published or assist in its implementation may be prepared, copied, published
and distributed, in whole or in part, without restriction of any and distributed, in whole or in part, without restriction of any
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