MOFI: Future Internet Architecture with Address-free Hosts for … · 2017-02-11 ·...

I. INTRODUCTION

With explosive growth of the number of subscribers of

2G/3G cellular systems and other wireless data systems,

the mobile users now become the key driver toward future

Internet. It is reported that the number of people who surf

the Internet on their mobile phones has doubled since

2006. By 2012, there will be much more mobile/wireless

users than wired ones.

However, it is noted that the current Internet was

originally designed for fixed hosts, rather than for mobile

ones, which has enforced to develop the extensional

features to Internet in order to support the mobile

environments, as shown in the examples of Mobile IPv6

(MIP) [1] and Proxy Mobile IPv6 (PMIP) [2]. However,

such patch-on approach seems to be just a temporal

heuristic rather than a sustainable solution to the mobility

issues to future Internet.

A lot of research activities have been initiated to design

the future Internet architecture for mobile environments. The

eMobility [3] is purposed to design the third generation

Internet for mobile users. The 4WARD [4] argues that the

future Internet architecture shall support mobile environment

effectively. We can also see a lot of activities on

wireless/mobile Internet in the FIND [5] and AKRAI [6]

projects. The IETF has also noted that the future internet

shall be able to support a large number of mobile devices [7].

Based on these observations, we can see that the current

Internet needs to be re-designed to effectively support the

mobile-oriented future Internet environments.

In this paper, we discuss an architectural design of

future Internet to support the mobile-oriented Internet

environment, named Mobile-Oriented Future Internet

(MOFI) [8]. The MOFI is designed with several key

design principles: address-free hosts, ID-based

communication with LOC-based routing, network-based

built-in mobility control, and support of heterogeneous

access networks.

This paper is organized as follows. Section II

discusses a set of design principles. In Section III, we

present the architecture of MOFI with the data transport

model. In Section IV, the mobility control procedures of

343

It is envisioned that mobile users will become the key driver toward future Internet. We propose a future Internet

architecture for mobile-oriented Internet environments, named Mobile-Oriented Future Internet (MOFI), which is based

on address-free hosts with host identifier (HID) and network locator (LOC). The MOFI is featured by the HID-based

communication with LOC-based routing and the support of heterogeneous access networks. We present the MOFI

architecture and describe the relevant procedures for data transport and mobility control. By numerical analysis, we see

that the proposed scheme can significantly improve the packet delivery cost and handover delay, compared to the

existing mobility protocols.

Keywords: Mobile oriented future internet, Host identifier, Network locator, Address-free hosts

논문번호: TR10-086, 논문접수일자:2010.10.04,, 논문수정일자:2011.02.10, 논문게재확정일자:2011.03.22

Heeyoung Jung: Electronics Telecommunications Research Institute (ETRI)

Seok Joo Koh: Corresponding author, Kyungpook National University (KNU)

MOFI: Future Internet Architecture with

Address-free Hosts for Mobile Environments

Heeyoung Jung ·Seok Joo Koh

MOFI are described with associated functional entities. In

Section V, the performance of the proposed MOFI scheme

is analyzed in terms of packet delivery cost and handover

delay. Finally, Section VI concludes this paper.

II. DESIGN PRINCIPLES

We first identify a set of design principles to design

the MOFI architecture.

1. Separation of Identifier and Locator

An Identifier (ID) is used to identify a user or host in

the network, whereas a Locator (LOC) represents the

current location of a host in the network. In the current

Internet, an IP address is used as ID as well as LOC. This

is because Internet has historically designed only for fixed

hosts and networks. However, in mobile-oriented network

environments, ID needs to be separated from LOC, since

LOC may change by movement, but ID will not change.

With the ID-LOC separation, a host can continue to move

across the networks with a constant ID, even though its

LOC changes frequently.

2. Address-free Hosts with Host Identifierand Network Locator

In mobile networks, the handover performance is

affected by the delay required for IP address configuration

in the network. As shown in the MIP, the handover

operation consists of movement detection, IP address

configuration, and binding update. When a mobile host

moves into a new network by handover, it should

configure a new IP address (e. g., by using the DHCP).

This address configuration tends to make the handover

delay much larger.

To reduce the handover delay we introduce the

address-free host, in which a host does not use any IP

address and thus the address configuration is not needed.

In MOFI, this address-free host feature is realized with

Host ID and Network LOC. That is, a host will use only an

ID without using the LOC (IP address), while an IP address

of the access router in the network is used as a LOC.

3. Support of Heterogeneous AccessNetworks

In the future network environments, there are so many

kinds of wireless/wired access networks. Furthermore,

each access network may have different characteristics. In

the meantime, the backbone network will be an optical

network with high bandwidth to provide reliable

transmissions.

In MOFI, to support a variety of heterogeneous access

networks, we separate the data delivery protocols for

access networks from the protocol for the backbone

network. In each access network, its underlying link-layer

protocol will be used for data delivery from hosts to the

access router. In the backbone network, however, the

current IPv4/IPv6 protocol is still used for data delivery

between access routers.

4. Built-in Mobility Control

To support mobile-oriented environments, the MOFI

provides the mobility control functions such as LOC binding,

LOC query, and handover control in the built-in fashion.

Note in current Internet that the mobility control protocols

are patched on IP, as shown in the MIP [1] and PMIP [2].

In particular, the MOFI performs the network-based

mobility control. It is noted that a network-based mobility

scheme is preferred to a host-based mobility scheme in the

viewpoint of deployment, performance, and resource

utilization, as we can see from comparison of MIP and

PMIP. In MOFI, all the mobility control functions are

performed by networks, rather than hosts.

III. ARCHITECTURE OFMOBILE-ORIENTED FUTURE INTERNET

1. Identifiers and Locator

1.1. Host Identifier (HID) and InterfaceIdentifier (IID)

In MOFI, HID is used to uniquely identify a host in

the network. For communication, a host is required to

know only the HID of the corresponding host rather than

the concerned LOC. It is assumed that a HID of MOFI is

the 128-bit identifier, which has the same length with an

IPv6 address.

Each host also has an Interface ID (IID) to identify a

network interface of host. The IID is used for packet

delivery between an access router and a host within an

access network. A specific format of IID depends on the

underlying link-layer access technology, such as the IEEE

802 MAC address, GPRS Tunnel ID, etc.

MOFI: Future Internet Architecture with Address-free Hosts for Mobile Environments 344

we assume that an AR is co-located with a PoA.

The Internet consists of a lot of routers. In MOFI, we

assume that the current IPv4 or IPv6 protocol is used for

packet routing in the backbone network.

3. Data Transport Model and Procedures

In MOFI, the application, transport, data link and

physical layer protocols will be used, as defined in the

current TCP/IP protocol stack. On the other hand, the

network layer protocol for data transport is divided into

the HID-based Communication Protocol (HCP) for end-

to-end communication and the Internet Protocol (IP) for

LOC-based routing. Note that the HCP is newly defined

in MOFI. The data delivery between host and AR in an

access network depends on the underlying link-layer

protocol, whereas the current IP protocol is used to deliver

data packets between ARs in the backbone network, as

shown in Figure 2.

In MOFI, data communication is accomplished with

HID rather than LOC. The sending host will initiate a

1.2. Locator (LOC)

LOC represents the location of a host in the network,

which is used for delivery of data packets in the Internet.

In MOFI, we will consider an IP address of the access

router (AR) as LOC. This LOC is also a routable IP

address for delivery of data packets in the network.

2. Network Model

To describe the MOFI architecture, we consider a

simplified network model, as shown in Figure 1.

We assume that each host has its own HID. The data

packet delivery between hosts and AR will be governed by

the protocol used in the underlying L2/L1 layer

technology, such as ethernet, GPRS, WiMAX, etc.

AR is the first-hop router to a host in the network,

which is responsible for delivery of data packets between

hosts in the network. The AR may be located with the

underlying Point of Attachment (PoA). Alternatively, two

or more PoAs may be connected to the AR. In this paper,

345 Telecommunications Review·Vol. 21 No. 2·2011. 4

L2/L1L2/L1 IIPP

IInntteerrnneett

HostHost

App/Trans

HCP

MAC/PHY

App/Trans

HCP

Host

IP IP

HostAccess Router Access Router

LOC-based IP routing

HID-based end-to-end communication

Figure 2. Data transport model in MOFI

MAC/PHY

MAC/PHY IID-based

access delivery

MAC/PHY

MAC/PHY

MAC/PHYIID-based

access delivery

LOC-based routing

HID-based communication

Figure 1. Network model in MOFI

AR ARRouter Router

WWiirreelleessssAAcccceessss((IIIIDD))

WWiirreelleessssAAcccceessss((IIIIDD))

HID HID

LOC LOC

The data packet transport procedures are summarized

as follows:

•Data transmission (Sender to AR)

Sender transmits the data packets to its AR. The HCP

header of the data packet contains the S-HID and R-

HID. The delivery from host to AR in the access

network is done based on the IIDs of Sender and AR. •Encapsulation (by AR of Sender)

On reception of data packets from Sender, the AR will

first identify the LOC of Receiver (R-LOC) associated

with the R-HID. For this purpose, AR performs the

LOC binding and query operations, which will be

described later. By this, the AR of Sender will get the R-

LOC. The AR of Sender will then encapsulate the HCP

data packets by adding an outer IP header that contains S-

LOC (AR of Sender) and R-LOC (AR of Receiver).•Packet delivery via IP routing in the backbone network

The encapsulated data packets will be delivered from S-

LOC to R-LOC by using the current IP routing protocol,


communication session with an HID of the receiving host.

The data delivery within an access network between a host

and AR will be done by using the IID of the concerned

host. LOC (IP address of AR) is used only for data

delivery in the backbone network.

Figure 3 shows the encapsulation of HCP data packet

into IP packet, which will be performed at each AR. The

HCP header contains Sender HID (S-HID) and Receiver

HID (R-HID). In the HCP packet, the upper-layer header

represents the headers of transport layer protocol such as

TCP or UDP. Each HCP data packet will be encapsulated

into the IP protocol at AR for data delivery. The IP header

contains Sender LOC (S-LOC) and Receiver LOC (R-

LOC), which represent the IP addresses of AR for Sender

and Receiver, respectively.

We design the HCP header by referring to the IPv6

header, since HID has the same length with IPv6 address,

as shown in Figure 4.

Then, the overall data transport operations are

summarized, as shown in Figure 5.

HCP Header

(S-HID,R-HID)Upper-layer Headers

Data

DataIP Header(S-LOC, R-LOC)

HHCCPP PPaacckkeett

EEnnccaappssuullaatteedd PPaacckkeett

HCP Header

(S-HID,R-HID)

Upper-layerHeaders

Figure 3. Encapsulation of HCP data packet into IP packet at AR

Figure 4. HCP header format

0 8 16 24 31

Version

ULP Reserved

Sender HID(128 bits)

Receiver HID(128 bits)

Payload Length

Upper Layer Protocol(TCP, UDP, etc)

Reserved

corresponding AR, possibly via an internal interface. For

mobility control, each MA performs the LOC Binding

(LB) and LOC Query (LQ) operations with LBS. The LB

operation is performed between MA and LBS when a host

is attached to a network, by which the LBS maintains the

HID-LOC information of the host within its LOC

database. The LQ operation is performed between MA

and LBS when a sending host transmits data packets to the

receiving host, so as to get the LOC of the receiving host.

On the other hand, for handover control, each MA

performs the Context Transfer (CT) and LOC Update

(LU) operations with the other MAs.

Table 1 shows the list of messages used for mobility

control. These control messages are exchanged between

MA and LBS or between MAs, which will be described

later. Note that all those messages are delivered by using

the TCP or UDP.

2. HID Binding

When a host enters the network, it will establish a

network connection with the concerned AR/PoA via an

possibly via one or more backbone routers in the network. •Decapsulation and Forwarding (by AR or Receiver)

On reception of the encapsulated data packets from AR

of Sender, the AR of Receiver will extract the original

HCP data packets by decapsulation. Then, it finds the

IID of Receiver by look up the Local Cache of AR that

has the mapping between HIDs and IIDs, which will be

described in the next section. After that, AR can

forward the HCP data packets to Receiver.•Data reception (AR to Receiver)

Finally, Receiver can receive the original HCP data

packets from its AR.

IV. MOBILITY CONTROL PROCEDURES

1. Functional Entities and Control Messages

Figure 6 shows the functional entities associated with

mobility control: Mobility Agent (MA) and LOC Binding

Server (LBS).

We assume that a MA is co-located with its


Access networkspecific routing

Access networkspecific routing

Figure 5. Data transport procedures

Figure 6. Functional entities for mobility control

IID IIDLOC HID Data DataHID HIDData

Sender ReceiverRouter Router

BBaacckkbboonnee NNeettwwoorrkk

LOC-based IP routing

AR AR

Host Host

LBS

MA

AR Router RouterInternet

Mobility Control Data Transport

MA

AR


appropriate link-layer connection establishment process.

With this network attachment, the HID binding operation

is performed implicitly by the underlying link-layer

protocol, as shown in Figure 7.

By the HID binding operation, each AR records and

maintains the HIDs and IIDs of the hosts into its Local

Cache. The abstract format of Local Cache is shown in

Table 2.

As shown in the table, the Local Cache of AR

maintains the list of HID and IID for all the hosts that are

attached to the AR. Each AR will refer to this information

for delivery of data packets to the local hosts. In the table,

the ‘status’ field (idle or active) represents whether or not

the host is in the active communication with the other

host. That is, ‘active’ means that the HID is bound to the

network and in communication with the other host(s),

while ‘idle’ implies that the host is bound, but not in

communication at that time.

3. LOC Binding

When an AR detects a new host in the network by

using the HID binding operation, its MA shall perform the

LB operation by sending a LBR message to the LBS

server. The LBR message shall include HID and LOC of

the host. Based on the LBR message, LBS will update its

location database (DB) by creating or updating the LOC

DB. Then, LBS will respond with a LBA message to the

MA. This LB operation will be performed, each time the

host moves into a new AR region, as shown in Figure 8.

From this LOC binding operation, the LBS server

constructs its LOC database that contains the mapping

information between HIDs and LOCs for all the hosts, as

shown in Table 3.

4. LOC Query and Data Transport

We assume that each host has completed the HID

Binding and LOC Binding operations. When Sender

transmits data packets to Receiver, the LQ operation is

Link Setup(HID, IID)

Figure 7. HID-IID binding between host and AR

Local CacheUpdate(HID:IID)

HHOOSSTT AARR//PPooAA

FFrroomm

MA

LBS

MA

LBS

MA

MA

MA

MA

TToo

LBS

MA

LBS

MA

(neighboring) MA

(neighboring) MA

(remote) MA

(remote) MA

PPaacckkeett TTyyppee

LBR

LBA

LQR

LQA

CTR

CTA

LUR

LUA

FFuullll NNaammee

LOC Binding Request

LOC Binding ACK

LOC Query Request

LOC Query ACK

Context Transfer Request

Context Transfer ACK

LOC Update Request

LOC Update ACK

OOppeerraattiioonnss

LOC Binding

LOC Query

Table 1. Types of control messages in MOFI

HandoverControl

IIIIDD

IID1

IID2

...

SSttaattuuss

Idle

Active

...

HHIIDD

HID1

HID2

...

NNoo..

1

2

3

Table 2. Local Cache of AR

LLOOCC

LOC1

LOC2

...

HHIIDD

HID1

HID2

...

NNoo..

1

2

3

Table 3. LOC Database of LBS


data packets to a remote host, whereas Local Cache is

used by AR to forward data packets to the locally attached

hosts in the subnetwork.

Then, the overall LQ and data transport operations are


•Sender transmits a data packet with R-HID toward

Receiver, which is delivered to AR of Sender;•MA of Sender will first look up its Remote Cache to

find the LOC of R-HID. If the corresponding cache

entry is found, the AR can directly deliver the data

packet to the identified AR (R-LOC), which is not

shown in the figure. Otherwise, if the corresponding

performed between MA and LBS. From this LQ

operation, each MA maintains its Remote Cache that

contains the list of HID and LOC of the remote hosts that

are in communication with the local hosts, as shown in

Table 4.

It is noted that Remote Cache is used by AR to send

HHoosstt HID

movement

LOC

HID Binding

LOC Binding ACK

LOC Binding ACK

LOC Binding Request(HID:LOC)

LOC DBUpdate

LOC DBUpdate

HID BindingLOC Binding Request

(HID:LOC)

Figure 8. LOC Binding Operations

Figure 9. Data Transport with Location Query

MMAA//AARR LLBBSS

RReemmoottee LLOOCC

LOC1

LOC2

...

RReemmoottee HHIIDD

HID1

HID2

...

NNoo..

1

2

3

Table 4. Remote Cache of MA

S-HID S-LOC R-LOC R-HID

HID Binding LOC Binding HID Binding

Data Packets(S-HID)

LOC Query Request(R-HID)

LOC Query ACK(R-LOC)

Encapsulated Data Packet(R-LOC:R-HID)

Encapsulated Data Packet(S-LOC:S-HID)

Data Packet to R-HID

Remote Cache Update(R-HID:R-LOC)

SSeennddeerr MMAA//AARR

LOC DB(R-HID:R-LOC)

Remote Cache Update(S-HID:S-LOC)

Remote CacheLookup(S-HID:S-LOC)

LLBBSS MMAA//AARR RReecceeiivveerr

LOC DB Lookup

Data Packet to R-HID

Data Packets to S-HID

Local Cache Lookup(for R-HID)

Local Cache Lookup(for S-HID)


cache entry is not found, the MA performs the LQ

operation by sending an LQR message to LBS. The

LBS responds to the MA with the associated R-LOC

via a LQA message. Based on the received LQA

message, MA of Sender will update its Remote Cache

table by creating the entry with R-HID and R-LOC.

Now, AR of Sender sends the encapsulated data packet

to AR of Receiver;•On reception of the encapsulated data packet from AR

of Sender, the AR of Receiver extracts the original HCP

data packet and updates its Remote Cache table by

creating a new entry with S-HID and S-LOC. This is

done for delivery of the data packets transmitted by

Receiver toward Sender. Then, after lookup of Local

Cache, the AR of Receiver will identify the IID of

Receiver. Based on the identified IID, the AR forwards

the original data packets to Receiver;•Now, Receiver transmits a data packet toward Sender.

On reception of data packet (with S-HID), the AR of

Receiver will look up the Remote Cache with S-HID to

find the S-LOC, which was already recorded in the

previous step. Thus, the encapsulated data packet will

be delivered to the AR of Sender; •On reception of an encapsulated data packet from AR of

Receiver, the AR of Sender decapsulates the packet,

and then find the IID of Sender by referring to its Local

Cache. Based on the IID, the AR will forward the data

packet to Sender;

Up to now, Remote Caches of Sender and Receiver

have been constructed. Based on this information, Sender

can exchange the data packets with Receiver, without

performing further LQ operation. This Remote Cache

ensures that the LQ operation is only once performed for

each remote host.

5. Handover Control

To describe the handover control operations, we

consider the handover scenario of Figure 10, in which

Receiver moves from the old MA/AR to the new MA/AR.

When a handover occurs, the Context Transfer operation

is performed between the two neighboring MAs (old MA

and new MA), and the LOC Update operation is

performed between the two corresponding MAs (local and

remote MAs).

Then, the handover control operations can be


•We assume that ARold gets a link-layer trigger such as

Link-Up of ARnew by handover, as per the IEEE

802.21 [9]. Then, MAold sends a Context Transfer

Request (CTR) to MAnew, which includes the

information of R-HID, S-HID, and S-LOC. The

MAnew responds with a Context Transfer ACK (CTA)

to MAold. By the Context Transfer operation, MAold

creates a Proxy Local Cache (R-HID:R-LOCnew),

which is referred to by ARold so as to forward the data

packets of R-HID to ARnew before the handover

control operation is completed. •When Receiver has a link connection with ARnew, it

performs the HID binding operation with ARnew, and

thus ARnew will update its Local Cache with R-

HID:R-IID. In addition, based on the CTR information,

MAnew temporarily creates its Remote Cache with S-

HID:S-LOC.

Figure 10. Handover Scenario

MA/AR

Sender

MA/ARoldHandover

MA/ARnew

Receiver

LOC Update

Context Transfer

V. ANALYSIS AND COMPARISON

1. Qualitative Comparisons

We first compare the proposed MOFI scheme with the

existing schemes in the perspective of ID-LOC separation

and mobility control.

1.1. ID-LOC Separation Schemes

For separation of ID and LOC, many proposals have

so far been proposed. Among those, the two representative

protocols are the Host Identity Protocol (HIP) [10] and the

Locator-Identifier Separation Protocol (LISP) [11]. Table

5 compares the proposed MOFI and the existing HIP and

LISP protocols.

Both HIP and LISP have been proposed to deal with

ID-LOC separation. The HIP is a host-based scheme,

•MAnew now sends the LOC Update Request (LUR)

message to MA of Sender. The MA of Sender will

update its Remote Cache table with R-HID: R-

LOCnew, and then respond with the LOC Update ACK

(LUA) message to the MA of Receiver. Based on this

LUA information, MAnew updates its Remote Cache

with S-HID:S-LOC.•Data path between Sender and Receiver is now changed

to Sender ↔ AR of Sender ↔ ARnew of Receiver ↔

Receiver.

In addition, the MA of Receiver will perform the LOC

Binding operation with LBS, when Receiver moves into a

new AR region, which is not shown in the figure. This

LOC Binding operation is for another host who will send

data packets to Receiver, which will be performed

independently of handover control.


Encapsulated Data Packets(S-LOC & R-LOCold)

Proxy Local Cache Update(R-HID:R-LOCnew)

Data Packets(S-HID & R-HID)

Remote Cache Update(S-HID:S-LOC)


Encapsulated Data Packets(S-LOC & R-LOCnew)

Context Transfer Request

Context Transfer ACK

LOC Update ACK(S-HID:S-LOC)

LOC Update Request(R-HID:R-LOCnew)

HID Binding

Local Cache Update(R-HID:R-IID)


Remote Cache Update(R-HID:R-LOCnew)


Figure 11. Handover Control Operations

LLIISSPP

Network-based

IP address of host

IP address of router

Used as ID in host

Required

Not supported

Not supported

FFeeaattuurreess

ID-LOC separation

ID

LOC

IP address in host

Address allocation

Seamless Mobility

Heterogeneous network

HHIIPP

Host-based

Host Identity Tag

IP address of host

Used as LOC in host

Required

Not Supported

Not supported

MMOOFFII

Network-based

Host ID

IP address of router

Not used in host

Not required

Supported

Supported

Table 5. Comparison of ID-LOC Separation Schemes

S-HID S-LOC R-LOCold R-LOCnew R-HID

SSeennddeerr MMAA//AARR MMAA//AARRoolldd MMAA//AARRnneeww RReecceeiivveerr

Handover(to ARnew)

which uses Host Identity Tag (HIT) as an ID and IP

address of a host as LOC. The LISP is a network-based

scheme, in which the IP address of host is used as an ID in

the local domain, and IP address of router is used as LOC.

In the meantime, the MOFI uses Host ID as ID, and uses

IP address of access router as LOC.

It is noted that both HIP and LISP use IP address of

host as LOC or ID, whereas MOFI does not use IP address

of host. That is, MOFI is based on the address-free host.

Accordingly, MOFI does not require the IP address

allocation in a host, whereas both HIP and LISP need the

IP address allocation such as Dynamic Host Configuration

Protocol (DHCP). Such address configuration tends to

make handover delay much larger. For this reason, HIP

and LISP are not easy to support seamless mobility.

However, MOFI can support seamless mobility, since IP

address configuration delay is not needed when a mobile

host moves into a new network region.

In addition, the MOFI is designed to support a variety

of heterogeneous access networks by separation of data

delivery protocols for access networks and backbone

networks.

1.2. Mobility Control Schemes

Now, we compare the proposed MOFI scheme with

the two representative mobility protocols, MIPv6 and

PMIPv6, in the perspective of mobility control

architecture, which is summarized in Table 6.

In terms of ID and LOC, the MIP uses IP addresses of

a host as Home Address (HoA) and Care-of Address

(CoA). The PMIP uses an IP address of Mobile Access

Gateway (MAG) as CoA, similarly to MOFI. However,

the HoA of PMIP is an IP address, whereas MOFI uses

HID rather than IP address.

In the viewpoint of control, MIP is the host-based

scheme, whereas PMIP and MOFI are the network-based

schemes. As mobility agents, the Home Agent (HA) of

MIP is similar to the Local Mobility Anchor (LMA) of

PMIP and the LBS of MOFI, and the MAG of PMIP

corresponds to MA of MOFI.

In the mobility control operations, both MIP and PMIP

perform only the LOC Binding operation, whereas MOFI

additionally uses the LOC Query operation for intrinsic

route optimization.

2. Numerical Analysis

Now, we compare the proposed MOFI scheme with

the two representative mobility protocols, MIPv6 and

PMIPv6, in the mobility performance perspective. For

performance analysis, we compare the Packet Delivery

Cost (PDC) and the HandOver Delay (HOD) for MIP,

PMIP, and MOFI. We first consider the two

MOFI: Future Internet Architecture with Address-free Hosts for Mobile Environment 352

TAR-LBSTHost-AR

TAR-LBS

Figure 12. Network model for numerical analysis

PPMMIIPP

IP address of host (HoA)

IP address of MAG (CoA)

Network-based

LMA, MAG

LOC Binding

FFeeaattuurreess

ID

LOC

Control

Agents

Operation

MMIIPP

IP address of host (HoA)

IP address of host (CoA)

Host-based

HA

LOC Binding

MMOOFFII

Host ID

IP address of AR

Network-based

LBS, MA

LOC Binding & Query

Table 6. Comparison of MIP, PMIP and MOFI

Sender AR AR

(MAG)

Receiver

LBS

Internet(MAG)

(HA/LMA)

TAR-AR

THost-AR

communicating hosts: Sender and Receiver. For

simplicity, we assume that both of the two hosts are

located within a single Internet domain. In the analysis,

we will ignore the security or AAA issues, etc.

Let us consider the following simplified network

model (See. Figure 12).

In the figure, AR represents AR of MIP, MAG of

PMIP, or MA of MOFI. Likewise, LBS represents HA of

MIP or LMA of PMIP. In the PMIP, we assume that

LMA is co-located with HA.

For analysis, we define Ta-b as the transmission delay

of a packet between two nodes (a and b) in the network.

This can apply to THost-AR, TAR-LBS, and TAR-AR. For

simplicity, we assume that all the transmission delays are

symmetric for forward and backward paths. It is also

assumed that all the node processing delays are relatively

small and negligible.

2.1. Packet Delivery Cost

In the packet delivery model, we assume that Sender

transmits N data packets to Receiver, and that Receiver

has already been registered with LBS/HA/LMA by using

the corresponding LOC Binding operations.

In MIP, the packet delivery cost from Sender to

Receiver can be calculated as follows:

•The first packet transmission from Sender to Receiver via

AR of Sender, HA, and AR of Receiver, which

corresponds to THost-AR+TAR-LBS+TAR-LBS+THost-AR;•The MIP route optimization from Receiver to Sender,

which is THost-AR+TAR-AR+THost-AR;•Now, the subsequent N-1 data packets are delivered

directly from Sender to Receiver, which results in (N-1)

x (THost-AR+TAR-AR+THost-AR).

Accordingly, the overall packet delivery cost of MIP

(PDCMIP) can be represented as

PDCMIP= (2THost -AR+2TAR-LBS)+ (2THost -AR+

TAR-AR)+(N-1) x (2THost-AR+TAR-AR)

=2THost-AR+2TAR-LBS+N x (2THost-AR

+TAR-AR). (Eq. 1)

In PMIP, for route optimization we consider the PMIP

Localized Routing (LR) [12], in which the LR operations

are divided into the two steps: ① LR initiation between

MAG and LMA, and ② establishment of tunnel between

MAGs of Sender and Receiver. The other procedures for

packet delivery are almost the same with those of MIP.

Accordingly, the packet delivery cost (PDCPMIP) from

Sender to Receiver can be calculated as follows:

•The first packet transmission from Sender to Receiver via

MAG of Sender, LMA, and MAG of Receiver, which

corresponds to THost-AR+TAR-LBS+TAR-LBS+THost-AR;•The PMIP LR operations between MAG and LMA, and

between MAGs of Sender and Receiver, which requires

2TAR-LBS+2TAR-AR;•The subsequent N-1 data packets are delivered directly

from Sender to Receiver, which results in THost-

AR+TAR-AR+THost-AR for each of N-1 packets.

The overall Packet Delivery Cost of PMIP (PDCPMIP)

can be represented as

PDCPMIP=(2THost-AR+2TAR-LBS)+(2TAR-LBS+2TAR-AR)

+(N-1) x (2THost-AR+TAR-AR)

=4TAR-LBS+TAR-AR+N x (2THost-AR+

TAR-AR). (Eq. 2)

In MOFI, on the other hand, the LOC Query operation

(at most once) is performed by AR of Sender before the

packet delivery to Receiver. After that, all the N data

packets are delivered directly to Receiver. So, the packet

delivery cost (PDCMOFI) from Sender to Receievr can be

calculated as follows:

•The LOC Query operation between AR of Sender and

LBS, which is 2TAR-LBS;•All the N data packets are delivered directly from

Sender to Receiver, which is 2THost-AR+TAR-AR.

The overall packet delivery cost of MOFI (PDCMOFI)

can be represented as

PDCMOFI=2TAR-LBS+N x (2THost-AR+TAR-AR). (Eq. 3)


2.2. Handover Delay

We now assume that Receiver moves from old AR to

new AR by handover during communications. For

analysis of handover delay, we define TMD as the

movement detection delay for establishment of a new link,

TAC as IP address configuration delay by using DHCP,

and Tone-hop as 1-hop wired transmission delay between

old AR and new AR, respectively.

In MIP, the handover delay (HODMIP) consists of the

following components:

•Movement detection of the new link in the ARnew

region, which is TMD; •Configuration of Care-of Address (CoA) in the AR

region, which is equal to TAC;•MIPv6 Route Optimization from Receiver to Sender,

which is THost-AR+TAR-AR+THost-AR;•Data transmission from Sender to Receiver after

handover, which is THost-AR+TAR-AR+THost-AR.

Accordingly, the overall handover delay of MIP

(HODMIP) can be represented as

HODMIP=TMD+TAC+2 (2THost-AR+TAR-AR) (Eq. 4)

In PMIP handover, the IP address (CoA) configuration

in the new region is not needed. Instead, the PMIP binding

update and route optimization operations are performed by

handover. Then, the handover delay (HODMIP) consists of

the following components:

•Movement detection of the new link in the new MAG

region, which is TMD; •PMIP binding update between MAG and LMA, which

is 2TAR-LBS;•Establishment of direct tunnel between two MAGs of

Receiver and Sender, which is 2TAR-AR;•Data transmission from Sender to Receiver after

handover, which is 2THost-AR+TAR-AR.

Accordingly, the overall handover delay of PMIP

(HODPMIP) can be represented as

HODPMIP=TMD+2TAR-LBS+2TAR-AR+2THost-AR

+TAR-AR

=TMD+2TAR-LBS+3TAR-AR+2THost-AR

(Eq. 5)

In MOFI, the IP address configuration is not required

during handover. Instead, the context transfer operation

between two neighbouring ARs (old and new ARs) is

needed, and then LOC Update operation will be

performed. Then, the handover delay (HODMOFI) consists

of the following components:

•Movement detection of the new link in the new AR

region, which is TMD; •Context Transfer Request and ACK between old and

new ARs, which is 2Tone-hop;•LOC Update operation between AR of Receiver and AR

of Sender, which is 2TAR-AR;•Data transmission from Sender to Receiver after

handover, which is 2THost-AR+TAR-AR.

Accordingly, the overall handover delay of MOFI

(HODMOFI) can be represented as

HODMOFI=TMD+2Tone-hop+2TAR-AR+2THost-AR

+TAR-AR

=TMD+2Tone-hop+3TAR-AR+2THost-AR

(Eq. 6)


MMiinniimmuumm

30 ms

50 ms

50 ms

100 ms

MMaaxxiimmuumm

300 ms

500 ms

500 ms

1000 ms

DDeellaayy

THost-ARTAR-LBSTAR-ARTAC

DDeeffaauulltt

150 ms

300 ms

200 ms

300 ms

DDeessccrriippttiioonn

Wireless link

One or more wired links

One or more wired links

DHCP delay

Table 7. Parameter values used for numerical comparison

3. Numerical Results

Based on the analytical equations, we now compare

the numerical results for the three schemes. In the

analysis, we assume that both Sender and Receiver are

within the same network domain so as to simplify the

analysis. That is, the inter-domain issue is not considered.

However, we believe that this analysis could fully reflect

the main features of each protocol.

For numerical analysis, we set the parameter values used

for numerical comparison as Table 7, which is based on the

works in [13]. As shown in the table, we vary the parameter

values with the minimum and maximum values, which is

purposed to evaluate the performance of each scheme in a

variety of network environments, such as variable

transmission delays between hosts and AR (THost-AR), or

between AR and LBS (TAR-LBS), or IP address

configuration delay (TAC). This sensitivity analysis is

helpful to see the impact of a specific parameter on

mobility performance. On the other hand, note that

TMD=100 ms and Tone-hop=50 ms are taken to be constant,

since these values are not dependent on the network

topology or environment.

Figure 13 and 14 compare the packet delivery costs of

candidate schemes by varying TAR-LBS and THost-AR.

Figure 13 shows the impacts of TAR-LBS on the packet


2500

2000

1500

1000

500

0

MIP

PMIP

MOFI

50 100 150 200 300 500

TAR-LBS (ms)

Figure 13. Impact of TAR-LBS on packet delivery cost

Packet Delivery Cost (ms)

1850

1650

1450

1250

1050

850

650

450

250

50

MIP

PMIP

MOFI

30 60 90 150 210 300

THost-AR (ms)

Figure 14. Impact of THost-AR on packet delivery cost

Packet Delivery Cost (ms)

delivery cost. TAR-LBS represents the distance between

AR and LBS (or HA). In the figure, it is shown that the

packet delivery cost gets larger for all the schemes, as

TAR-LBS increases. The PMIP is much more affected by

TAR-LBS than MIP and MOFI. We note that the proposed

MOFI scheme provides lower packet delivery costs than

the existing two schemes. This is because the MOFI

scheme performs the intrinsic route optimization with the

LOC Query operation before data transmission, whereas

MIP and PMIP do the route optimization after data

transmission, and such operations tend to rely on the

transmission delay between AR and HA/LMA.

Figure 14 shows the impacts of THost-AR on the packet

delivery cost. THost-AR represents the transmission delay

of wireless link between host and AR. The network-based

mobility schemes, PMIP and MOFI, are not affected by

THost-AR, whereas the host-based MIP depends on the

transmission delay of wireless link and thus the packet

delivery cost gets larger as THost-AR increases. From the

results, we see that the MOFI scheme provides better

performance than the MIP and PMIP schemes. This is

because the proposed MOFI scheme performs the

network-based mobility control as well as intrinsic route

optimization.

Figure 15 through 17 compare the handover delays of

the candidate schemes.


2100

1900

1700

1500

1300

1100

900

700

MIP

PMIP

MOFI

30 60 90 150 210 300

THOST-AR (ms)

Figure 15. Impact of THost-AR on handover delay

Handover Delay Cost (ms)

3000

2500

2000

1500

1000

500

MIP

PMIP

MOFI

50 100 150 200 300 500

TAR-AR (ms)

Figure 16. Impact of TAR-AR on handover delay


Figure 15 shows the handover delays for different

THost-AR. From the figure, it is shown that the host-based

MIP scheme severely depends on the transmission delay

of wireless link (THost-AR). The network-based mobility

schemes, PMIP and MOFI, give lower handover delays

than MIP. In particular, we see that the proposed MOFI

scheme provides lower handover delay than the two

existing schemes. This is because the proposed MOFI

scheme is based on address-free host and thus it does not

require address configuration (TAC), which is very helpful

to reduce the handover latency.

Figure 16 shows the impacts of TAR-AR on the

handover delay. TAR-AR represents the transmission

delays between AR of Sender and AR of Receiver in the

multi-hop wired network. From the figure, we can see that

all the schemes depend on TAR-AR, and the proposed

MOFI scheme give smaller handover delays than the

existing MIP and PMIP schemes. This performance

benefit comes from the address-free host feature of MOFI.

However, the performance gaps of the proposed and

existing schemes are reduced, when TAR-AR gets

extremely large.

Figure 17 shows the impacts of address configuration

delay (TAC) on the handover delay. From the figure, we

can see that the MIP scheme severely depends on the

address configuration delay, whereas PMIP and MOFI are

not affected by TAC. The proposed MOFI scheme gives

the best performance than the existing MIP and PMIP

schemes. Such the performance gain comes from the

address-free host and network-based built-in mobility

control features of MOFI.

VI. CONCLUSIONS

In this paper, we have proposed a new internet

architecture with address-free hosts and separation of

identifier and locator, named Mobile-Oriented Future

Internet (MOFI), and presented the associated protocols to

realize the MOFI architecture in the future Internet

environment. The MOFI can be viewed as a clean-slate

approach for design of future Internet, in which the HID-

based Communication Protocol (HCP) is newly proposed

for end-to-end data transport. The MOFI can also be

regarded as an incremental approach in that the current IP

is used for data delivery in the backbone network. The

proposed MOFI has several distinctive features: Host ID

and network LOC, address-free hosts, HID-based

communication with LOC-based routing, network-based

built-in mobility control, and separation of access and

backbone network protocols for data delivery. From

numerical analysis, it is shown that the proposed MOFI

can provide better performance than the existing MIP and

PMIP schemes in the packet delivery cost and handover

delay.

For future works, the proposed MOFI architecture and

operations need to be enhanced in a more scalable and

efficient manner. We also plan to perform the

experimentation of the MOFI protocol in the realistic

testbed network [8].

AcknowledgementsThis research was partly supported by the IT R&D


2200

2000

1800

1600

1400

1200

1000

MIP

PMIP

MOFI

100 200 300 500 700 1000

TAC (ms)

Figure 17. Impact of TAC on handover delay


program of MKE/KEIT (10035245: Study on Architecture

of Future Internet to Support Mobile Environments and

Network Diversity), the ITRC program of MKE/NIPA

(NIPA-2011-C1090-1121-0002), and the Basic Science

Research Program through the NRF of Korea funded by

the MEST (2010-0020926).

[References][1] D. Johnson, et al., Mobility Support in IPv6, IETF RFC

3775, Jun. 2004.[2] S. Gundavelli, et al., Proxy Mobile IPv6, IETF RFC

5213, Aug. 2008.[3] eMobility Project, http://www.emobility.eu.org/[4] 4WARD Project, http://www.4ward-project.eu/[5] Future Internet Design (FIND), http://www.nets-

find.net/[6] AKARI, http://akari-project.nict.go.jp/eng/[7] D. Meyer, et al., Report from the IAB Workshop

on Routing and Addressing, IETF RFC 4984, Sep. 2007.

[8] Mobile Oriented Future Internet (MOFI) homepage, http://www.mofi.re.kr

[9] IEEE 802.21, Media Independent Handover (MIH) Services, http://www.ieee802.org/21/

[10] R. Moskowitz, et al., Host Identity Protocol (HIP), IETF RFC 5201, Apr. 2008.

[11] D. Farinacci, et al., Locator/ID Separation Protocol (LISP), IETF Internet Draft, draft-ietf-lisp-10.txt, Mar. 2011.

[12] S. Krishnan, et al., Localized Routing for Proxy Mobile IPv6, IETF Internet Draft, draft-ietf-netext-pmip-lr-01.txt, Oct. 2010.

[13] K. Kong, et al., ''Mobility Management for All-IP Mobile Networks: Mobile IPv6 vs. Proxy Mobile IPv6,'' IEEE Wireless Communications, Vol. 15, No. 2, Apr. 2008, pp. 36-45.


Heeyoung Jung

He joined Electronics and Telecommunication

Research Institutes (ETRI) in 1991 after receiving

bachelor degree from Pusan National University (PNU)

and is currently a principal research member. He received

his Ph. D. degree in Information and Communications

Engineering from the Chungnam National University

(CNU) in 2004. His major research areas include Internet

and mobile network technologies and are closely related to

standardization activities in ITU-T, IETF, etc. His current

research topic is future Internet architecture.

E-mail: [email protected]

Seok Joo Koh

He received the B.S. and M.S. degrees in Management

Science from KAIST in 1992 and 1994, respectively. He

also received Ph.D. degree in Industrial Engineering from

KAIST in 1998. From August 1998 to February 2004, he

worked for Protocol Engineering Center in ETRI. He has

been as a professor with the school of Computer Science

and Engineering in the Kyungpook National University

since March 2004. His current research interests include

mobility management in the future Internet, IP mobility,

multicasting, and SCTP. He has so far participated in the

international standardization as an editor in ITU-T SG13

and ISO/IEC JTC1/SC6.

E-mail: [email protected]

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