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A Multi-link architecture for a global wireless Internet connectivity

Guillaume BichotThomson Corporate Research

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Content

• Multi-link technologies: state of the art– Channel bonding– Layer 2 multilink– Layer 3 multilink– Drawbacks

• Network Inter-working concept • Always Best Connected (ABC) concept• A multilink service

– The multilink gateway– The tunneling method– The multilink control protocol– The multilink core network– Advantages and issues

• Conclusion

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Channel BondingGateway

Channel bonding capable terminalConventional Terminal

Virtual channel

Ethernet switchChannel bonding capable

Ethernet channel bondingIncr

ease

ban

dwid

than

d th

roug

hput

Sim

ple

tech

nolo

gy

LAN

tech

nolo

gy

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Layer 2 MultiLink

Service providerNetwork

terminal

ML-PPP capable terminal

ML-PPP capable access multiplexer

ML-PPP CPE

ML-PPP capableaccess multiplexer

2 ISDN B Channels or2 T1/E1 channels or

2 xDSL lines

Multi-Link PPP (ML-PPP) MultiLink Frame Relay (MFR)

Inverse Multiplexing over ATM (IMA)Enha

nced

relia

bilit

yIn

crea

se b

andw

idth

and

thro

ughp

ut

Serv

ice

prov

ider

dep

enda

nt

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Layer 3 Multilink

Internet

terminal

ISP B access gateway

ISP A access gateway

any kind of broadbandaccess technology

WEB server

ML-gateway LAN

ISP D access gateway

ISP C access gateway

DNS ServerML-gateway

Multilink based on multi-homing (several home IP addresses) En

hanc

ed re

liabi

lity

Incr

ease

ban

dwid

th/ I

SP in

depe

nden

t

ML

on se

ssio

nba

sis o

nly

ML

inbo

und

conn

ectio

ns b

ased

on

DN

S

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Unidirectional Link Routing (UDLR)

Internet

terminal

ISP access gateway

UDLRModem

UDLR gateway

Satellite

Return path: IP tunnelover a bi-directionalnetwork

Application

TCP/UDP

IP

UDLR

BI UI

Application

TCP/UDP

IP

UDLR

BI UI

WEB server

ISP access gateway

Based on RFC 3077: Link layer Tunneling MechanismUni

dire

ctio

nal n

etw

orks

use

d fo

r bi-

dire

ctio

nal b

road

band

acc

ess

No

inbo

und

path

sele

ctio

nO

ne u

plin

k ac

cess

net

wor

k

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Multilink drawbacks

• Multi-homing– How to deal with multiple home IP addresses

• Nomadicity and mobility– How to deal with vertical roaming– How to deal with service continuity

• Inbound connection– No easy control of the inbound path selection– Only possible through the usage of DNS

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WLAN – 3GPP Interworking

May

not

be

adap

ted

to d

iffer

ent a

cces

s ne

twor

k te

chno

logi

es

A g

loba

l AA

A m

odel

for p

ublic

br

oadb

and

acce

ss

InternetVisited network

terminal

Gateway

WLAN AP

Local AAA server

Home Network

Home AAA server

Billing

Subscribersdata base

AuthorizationAuthenticationAccountingbased onIEEE 802.1x

AAABroker

Several Initiatives (IEEE, 3GPP) in order to standardized the roaming model

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Always Best Connected (ABC)Content

adaptation

AccessNetwork

ABC Network

Corporate Network

Remote Terminal

ABC Terminal

• Always connected• Through the Best access

technology according to:– User preferences– Terminal capabilities– Application requirement

(qos)– security– Network resources– Network policy

Profile Handling

Mobility Management

AAASupport

AccessDiscovery &

Selection

ABC Model

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A Multilink Service

Multi-linkNetwork

Access networkA

Access networkB

Access networkC

PDA

Combining state of the art multilink technologies lead to a new network service

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The Multilink Gateway

Internet

ML terminal

ISP Aaccess gateway

ML gateway

One logical linkcomposed with several

IP tunnels

Application

TCP/UDP

IP

Multilink

Link/phylayer

WEB server

ISP Caccess gateway

ISP Baccess gateway

Application

TCP/UDP

IP

Multilink

IP

LinkB

LinkA

Acts as the access network multiplexerAggregates IP tunnels Th

e M

L G

atew

ay p

rovi

des t

unne

l sel

ectio

n m

echa

nism

for d

ownl

ink

traff

ic

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The Tunneling Method

M u ltilin k

IP

P h y

G R E

L in k

P h yL in k

P h y

IP

M u lti- lin kte rm in a l

M u lti- lin kG a te w a y

W E B s e rve r

T C P

A p p li

3 G P P

P h y

In te rn e t

M u lti- lin kC o n tro l

W iM A x

C o n tro lM u lti- lin kC o n tro l

@ IP IS P 1

@ IP IS P 2

E th e rn e t

IP

@ IP m u lti- lin k IS PT C P /U D P

IP

G R E

E th e rn e t

IP

T C P /U D P

The tunneling method is based on LLTMGR

E (G

ener

ic R

outin

g En

caps

ulat

ion)

pro

vide

s a

pseu

do E

ther

net l

ink

over

seve

ral a

cces

s lin

ks

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The Multilink Control Protocol

• Authentication, Authorization Accounting– May be distributed over access networks based on a global

AAA inter-working framework• Address assignment

– Multilink service provider (home)IP address• Security material

– Encryption • Backup multilink gateway• Link discovery

– Availability and performance testing– User profile (preferences)

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The Multilink core network

Multilink CoreNetwork

ML terminalML gateway

ML gateway

ML gateway

Multilink (logical) link

PDA

The ML gateways are interconnected through either dedicated links or InternetPr

ovid

es sc

alab

ility

and

relia

bilit

yEn

hanc

ed e

ffic

ienc

y (e

.g. M

L ga

tew

ay lo

cate

d in

ISP

netw

orks

)

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Advantages and issues

• Link selection– Real inbound and outbound

path selection possible– On a packet or session basis– Driven by

•User profile•links availability and QOS•Application type

• Operates any access networks– PAN (bluetooth)– LAN (WiFi)– WAN (WiMAX, 3GPP)

• Multi-homing and Mobility– Inherently solved

• Distributed AAA• ABC selection mechanism

– May be complicated to develop • Tunneling method

– Efficiency (overhead)• Service continuity

– Vertical handover

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Conclusion

• A multilink network architecture – ISP neutral– Access network transparent

• Automatic link selection– For outbound as well inbound traffic– Provides bandwidth gain– QOS friendly– Always Best Connected

• Particularly suited for wireless (mobile) connectivity– A wireless (mobile) device should gather several interfaces

• E.G. Bluetooth, WiFi, cellular (3GPP), WiMAX

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References• Multilink

– « Inverse multiplexing over ATM» - Quick Eagle Networks– « Multilink technology white paper » - Stonesoft– « The PPP Multilink protocol » – IETF RFC 1990

• UDLR– « A link layer tunneling mechanism for unidirectional links (LLTM)» - IETF RFC 3077

• Multihoming– « Integrating security, mobility and multi-homing in a HIP way » - Pekka Nikander,

Jukka Ylitalo, Jorna Wall – Ericsson Research• Always Best Connected (ABC)

– « Always Best Connected » - Eva Gustafsson, Amika Johson – Ericsson Research– « On access selection techniques in Always Best Connected networks » - Gàbor

Fodor, Anders Furuskär, Joahan Lundsj – Ericsson Research• Cellular (3GPP) WLAN (WiFi) interworking

– « Interworking techniques and architectures for WLAN/3G integration towards 4G Mobile data networks » – Apostolis K. Salkintzis