edge mobility architecture

IPCN2000, Paris, France©1997 British Telecommunications plc

Edge Mobility Architecture

Alan O’Neill, BT Adastral Park

Scott Corson, University of Maryland

George Tsirtsis, BT Adastral Park

May 2000


Objectives• Solve IP mobile routing and fast restoration

– Homogeneous hand-over between heterogeneous technologies

– Very large-scale domains

• Why?– VoIP with high availability, real-time services – 3G migration to Internet architecture– Fixed/Mobile Convergence


Fixed MobileConverged Domain

Convergence - UMTS ++

Radio LAN’s

Bluetooth

Cellular Mobile

DialAccess

CorporateAccess


EMA Hand-over Architecture

TempTunnel

NAR

Update

Update

Hand-over? (AAA)

OAR


Break before Make

OAR NAR

MH

OAR NAR

MH

tunnel OAR NAR

MH

OAR NAR

MH

tunnel OAR NAR

MH

(a) before handover (b) sensing new link, build tunnel

(e) break occurs(c) inject new routing on make (d) routing converges,tear down tunnel

OAR NAR

MH

OAR NAR

MH

tunnel OAR NAR

MH

tunnel OAR NAR

MH

tunnel OAR NAR

MH

(a) before handover (b) sensing new link,build tunnel

(c) tunnel data on break (d) inject new routing on make,forward cached data (if any)

(e) routing converges,tear down tunnel

Make before Break


Mobile IPv6 & EMA

1. EMA

OARAAR

• AAR is CoR for MN-HA and HA for CoA• TORA MER moves CoA within domain• One CoA, Reg and BU per domain• Improved speed, reduced delay

NAR

HACN

To CoA (native or RH)


Inter-domain Mobile IP

1. EMA 2. OSPF

OAR NARAARSAR

Tunnels

Native

• Native forwarding in EMA domains• MIP tunnels / bindings inter-domain• MIP tunnels / bindings in OSPF domains


Present GPRS/UMTS

SGSN

SGSN

GGSNx

GGSNy

ISPx

ISPy

PublicAddress Allocators

Private GPRS Domain

GTPTunnelling

Local ServicesWeb hostingMulticast, QoSLocal Traffic


GGSNv4/v6

SGSN*AAA/DHCP RNC

RNC

DSLAM

GGSNv4/v6

Corp

ISP

IP in the RNCSGSN out of data-path

DHCP/[email protected]+Key

E.gWaveLan

xDSL

EMA DomainRouting

Local ServicesWeb hostingMulticast, QoSLocal Traffic


Tora -> Localization = Scalability

Handover

• no far-reaching control messages• eliminates convergence problem


Tora -> local decisions & loop-free

• Totally-ordered heights -> “gravity”• Packets have to go uphill to form loop

DEST

SOURCES


Tora Fast Restore

- Rapidly detects link/node failures

DEST

SOURCES


Tora Fast Restore

• immediate localized reaction •critical for premium VoIP etc

DEST

SOURCES


Hierarchical Mesh TopologyCR CR CR

IR IRIR IR IR

ER ER ER ER ER ER ER ER ER

AR AR AR AR AR AR AR AR AR AR AR AR AR AR AR AR AR AR AR

• CRs form full mesh (clique) at top level• IRs, ERs and ARs dual-homed for robustness• Order of magnitude increase in routers at each level (e.g. 10 CRs, 100 IRs, 1000 ERs, 10000 ARs, etc.)


CR CR CR

IR

ER

AR

ER

IR IR

ER

AR AR

Prefix DAG per Access Router

• Inject prefix(es) into ‘unordered’ domain from Access Router


Prefix DAG per Access Router

•‘Order’ all links towards each AR - aggregated DAG• DAG rooted at receiving mobile host (MH) i.• Relevant node heights with initial hop count shown

CR CR CR

IR

ER

AR

ER

IR IR

ER

AR AR(0,0,0,1,i)

(0,0,0,2,i)

(0,0,0,3,i)

(0,0,0,4,i)

(0,0,0,5,i)

(0,0,0,3,i)

(0,0,0,4,i)

(0,0,0,5,i)

(0,0,0,4,i) (0,0,0,4,i) (0,0,0,5,i)

(0,0,0,5,i)


IP address per active IP session

• Mobile Host (MH) wants to send / receive IP packets• Gets allocated IP address from AAR prefix

CR CR CR

IR

ER

AR

ER

IR IR

ER

AAR AR(0,0,0,1,i)

(0,0,0,2,i)

(0,0,0,3,i)

(0,0,0,4,i)

(0,0,0,5,i)

(0,0,0,3,i)

(0,0,0,4,i)

(0,0,0,5,i)

(0,0,0,4,i) (0,0,0,4,i) (0,0,0,5,i)

(0,0,0,5,i)

MH(0,0,0,0,i)

AAA


In-session (active) Mobility Profile

d

PD/T(d)

d

• D = geographical distance moved• T = session duration (IP address effective lifetime)• Assumption: Movement Localized (in probability)

Session begins at any Access RouterSession terminated on inactivity timer

profile is a function of T

(distance moved)

(pro

bab

ilit

y)

MH


Host Route InjectionCR CR CR

IR IRIR IR IR

ER ER ER ER ER ER ER ER ER

AR AR AR AR AR AR AR AR AR AR AR AR AR AR AR AR AR AR AR

MH

• Movement further from AAR deepens injection towards core


• Shows data flow from MH to MH via default DAG

“Make Before Break”CR CR CR

IR

ER

AR

MH

ER

IR IR

ER

AR

MH

Ongoingcall tomobile

(0,0,0,1,i)

(0,0,0,2,i)

(0,0,0,3,i)

(0,0,0,4,i)

(0,0,0,5,i)

(0,0,0,3,i)

(0,0,0,4,i)

(0,0,0,5,i)

(0,0,0,0,i)

(0,0,0,4,i) (0,0,0,4,i) (0,0,0,5,i)

(0,0,0,5,i)

AR


CR CR CR

IR

ER

MH

ER

IR IR

ER

MH

• Mobile senses signal but has no new link (yet)• Sends “Tunnel Initiation” (TIN) packet to old AR• Computes its new height and sends it in TIN packet

(0,0,0,1,i)

(0,0,0,2,i)

(0,0,0,3,i)

(0,0,0,4,i)

(0,0,0,5,i)

(0,0,0,3,i)

(0,0,0,4,i)

(0,0,0,5,i)

(-1,0,0,0,i)

TIN

(0,0,0,4,i) (0,0,0,4,i) (0,0,0,5,i)

(0,0,0,5,i)

AR AR AR


CR CR CR

IR

ER

MH

ER

IR IR

ER

MH

tunnel

•Old AR establishes tunnel link to new ARs•Sets its view of tunnel height equal to (-1,0,0,1,i)•Old AR forwards TIN packet to new AR

(0,0,0,0,i)

(0,0,0,2,i)

(0,0,0,3,i)

(0,0,0,4,i)

(0,0,0,3,i)

(0,0,0,4,i)

(0,0,0,5,i)

TIN

(0,0,0,5,i)

(-1,0,0,0,i)

(-1,0,0,1,i)

(0,0,0,4,i) (0,0,0,4,i) (0,0,0,5,i)

(0,0,0,5,i)

AR AR AR


CR CR CR

IR

ER

MH

ER

IR IR

ER

MH

• TIN most likely arrives and is cached.• On L2 ‘make’, generate UUPD if TIN cached, or generate when TIN or L3M arrives at new AR

(0,0,0,1,i)

(0,0,0,2,i)

(0,0,0,3,i)

(0,0,0,4,i)

(0,0,0,3,i)

(0,0,0,4,i)

(0,0,0,5,i) (0,0,0,5,i)

(-1,0,0,0,i)

(-1,0,0,1,i)

(0,0,0,4,i) (0,0,0,4,i) (0,0,0,5,i)

(0,0,0,5,i)

AR AR ARtunnel


CR CR CR

IR

ER

MH

ER

IR IR

ER

MH

UUPD

•Make event occurs, send UUPD•If UUPD travels fast enough, data tunnel not needed

(0,0,0,1,i)

(0,0,0,2,i)

(0,0,0,3,i)

(0,0,0,4,i)

(0,0,0,5,i)

(0,0,0,3,i)

(0,0,0,4,i)

(0,0,0,5,i)

(-1,0,0,0,i)

L3M (if mobile assist)

(0,0,0,4,i) (0,0,0,4,i) (0,0,0,5,i)

(0,0,0,5,i)

(-1,0,0,1,i)

AR AR ARtunnel


CR CR CR

IR

ER

MH

ER

IR IR

ER

MH

•Loss of link--old AR forwards data through tunnel•Tunnel exists to prevent TORA reaction at old AR•TORA UUPD continues propagation

(0,0,0,1,i)

(0,0,0,2,i)

(0,0,0,3,i)

(0,0,0,4,i)

(0,0,0,5,i)

(0,0,0,3,i)

(0,0,0,4,i)

(0,0,0,5,i)

(-1,0,0,0,i)

(0,0,0,4,i) (0,0,0,4,i) (0,0,0,5,i)

(0,0,0,5,i)

(-1,0,0,2,i)

(-1,0,0,1,i)

AR AR ARtunnel


CR CR CR

IR

ER

MH

ER

IR IR

ER

MH

•TORA update hits a crossover router

(0,0,0,1,i)

(0,0,0,2,i)

(0,0,0,3,i)

(0,0,0,4,i)

(0,0,0,5,i)

(0,0,0,3,i)

(0,0,0,4,i)

(0,0,0,5,i)

(-1,0,0,0,i)

(0,0,0,4,i) (0,0,0,4,i) (0,0,0,5,i)

(0,0,0,5,i)(-1,0,0,3,i)

(-1,0,0,2,i)

(-1,0,0,1,i)

AR AR ARtunnel


CR CR CR

IR

ER

MH

ER

IR IR

ER

MH

•Crossover routers re-order links and divert data•Tunnel ‘holdsdown’ TORA reaction at old AR• Tunnel state removed when UUPD hits old AR

(0,0,0,1,i)

(0,0,0,2,i)

(0,0,0,3,i)

(0,0,0,4,i)

(0,0,0,5,i)

(0,0,0,3,i)

(0,0,0,4,i)

(0,0,0,5,i)

(-1,0,0,0,i)

(-1,0,0,1,i)

(0,0,0,4,i) (0,0,0,4,i) (0,0,0,5,i)

(0,0,0,5,i)

(-1,0,0,4,i)

(-1,0,0,3,i)

(-1,0,0,2,i)

(-1,0,0,1,i)

AR AR ARtunnel


CR CR CR

IR

ER

MH

ER

IR IR

ER

MH

•Old AR updates height and tears down tunnel•Only (5) nodes in green have updated heights•UUPD-Ack propogates back to new AR (not shown)

(0,0,0,3,i)

(0,0,0,4,i)

(0,0,0,5,i)

(-1,0,0,0,i)

(0,0,0,4,i) (0,0,0,4,i) (0,0,0,5,i)

(0,0,0,5,i)

(-1,0,0,4,i)

(-1,0,0,3,i)

(-1,0,0,2,i)

(-1,0,0,1,i)(0,0,0,1,i)

(0,0,0,2,i)

(0,0,0,3,i)

(0,0,0,4,i)

(0,0,0,5,i)AR AR AR(-1,0,0,5,i)


CR CR CR

IR

ER

MH

ER

IR IR

ER

MH

•Subsequent movement...

(0,0,0,3,i)

(0,0,0,4,i)

(0,0,0,5,i)

CR

IR

ER

AR

(0,0,0,5,i)

(0,0,0,6,i)

(0,0,0,6,i)

(0,0,0,7,i)

(0,0,0,8,i)

(-1,0,0,0,i)

(0,0,0,4,i)(0,0,0,4,i) (0,0,0,5,i)

(-1,0,0,4,i)

(-1,0,0,3,i)

(-1,0,0,2,i)

(-1,0,0,1,i)(0,0,0,1,i)

(0,0,0,2,i)

(0,0,0,3,i)

(0,0,0,4,i)

(0,0,0,5,i)AR AR AR(-1,0,0,5,i)


CR CR CR

IR

ER

MH

ER

IR IR

ER

MH

... results in similar behavior

(0,0,0,3,i)

(0,0,0,4,i)

(0,0,0,5,i)

CR

IR

ER

(0,0,0,4,i)(0,0,0,4,i) (0,0,0,5,i)

(-2,0,0,5,i)

(-2,0,0,4,i)

(-2,0,0,3,i)

(-2,0,0,2,i)

(-2,0,0,1,i)

(-2,0,0,0,i)

(0,0,0,5,i)

(0,0,0,6,i)

(0,0,0,6,i)

(0,0,0,7,i)

(0,0,0,8,i)(-1,0,0,5,i)

(-1,0,0,3,i)

(-2,0,0,6,i)

(-2,0,0,7,i)(0,0,0,1,i)

(0,0,0,2,i)

(0,0,0,3,i)

(0,0,0,4,i)

(0,0,0,5,i) ARAR AR AR

(-1,0,0,4,i)


• When mobile powers off, DAG is erased • Current AR hands address back to home AR • ‘Unicast-Directed Erase Update’ (UDEU)

MH(0,0,0,0,i)

DAG ErasureCR CR CR

IR

ER ER

IR IR

ER

(0,0,0,3,i)

(0,0,0,4,i)

(0,0,0,5,i)

CR

IR

ER

(0,0,0,4,i)(0,0,0,4,i) (0,0,0,5,i)

(-2,0,0,5,i)

(-2,0,0,4,i)

(-2,0,0,3,i)

(-2,0,0,2,i)

(0,0,0,5,i)

(0,0,0,6,i)

(0,0,0,6,i)

(0,0,0,7,i)

(0,0,0,8,i)(-1,0,0,5,i)

(-1,0,0,4,i)

(-1,0,0,3,i)

(-2,0,0,6,i)

(-2,0,0,7,i)(0,0,0,1,i)

(0,0,0,2,i)

(0,0,0,3,i)

(0,0,0,4,i)

(0,0,0,5,i)

UDEU

ARAR AR AR


CR CR CR

IR

ER ER

IR IR

ER

MH

(0,0,0,1,i)

(0,0,0,2,i)

(0,0,0,3,i)

(0,0,0,4,i)

(0,0,0,5,i)

(0,0,0,3,i)

(0,0,0,4,i)

(0,0,0,5,i)

CR

IR

ER

(0,0,0,5,i)

(0,0,0,6,i)

(0,0,0,7,i)

(0,0,0,8,i)

(0,0,0,9,i)

(0,0,0,0,i)

•DAG restored to original condition.•Home AR sends Erase Update Ack (EUA)•Current AR completes 3-way handshake (EUA-Ack)

(0,0,0,4,i)(0,0,0,4,i) (0,0,0,5,i)

UDEU

EUA

EUAA

ARAR AR AR


Scalable Native-Routed Mobility

CRs

IRs

ERs

ARs

Scaled for 200 hosts per AR- 4CRs, 16IRs, 160ERs, 1600ARs- 320000 mobile hosts in domain

dual-homed topology

• Approx. 2000 Routers and 320000 mobile hosts• Max. Avg. Route Table Size approx. 13200 routes with native IP routing.

Route Table Size

0 5000 10000 15000

Access Router

Edge Router

Inter. Router

Core Router

Rout

er T

ype

Number of Routes

AR (subnet) Routes

Mobile Host Routes


Questions?


Active Mobile Route Injection

CRs

IRs

ERs

ARs

•Scaled for 200 hosts per AR

single-homed topology

• Number of host routes per router increases towards core

Host Route Injection

0 5000 10000 15000 20000

Access Router

Edge Router

Inter. Router

Core Router

Rout

er T

ype

Host Routes per Router

CR2_ER4_AR16

CR4_ER16_AR144

CR4_ER40_AR400

CR4_IR16_ER160_AR1600


Host Route Injection (percentage)

0 10 20 30 40 50

Access Router

Edge Router

Inter. Router

Core Router

Rout

er T

ype

Host Routes per Router as Percentage of Total Hosts

CR2_ER4_AR16

CR4_ER16_AR144

CR4_ER40_AR400

CR4_IR16_ER160_AR1600

Domain Scaling Effects

CRs

IRs

ERs

ARs

single-homed topology

• Number of host routes per router decreases as domain size increases


Host Route Injection

0 1 2 3 4 5 6

Access Router

Edge Router

Inter. Router

Core Router

Route

r Typ

e

Host Routes per Router as Percentage of Total Hosts

CR4_IR16_ER160_AR1600

D_CR4_IR16_ER160_AR1600

Effect of Dual-Homed Topology

CRs

IRs

ERs

ARs

dual-homed topology

• Dual-homed: host state disappears from Core Routers • redistributed to more numerous Edge Routers


Comparison with HAWAII

CRs

IRs

ERs

ARs

Scaled for 277 mobiles per AR (BS)- 4CRs, 16IRs, 160ERs, 1600ARs

- 442514 active mobiles in domain

dual-homed topology

• Max. Avg. Route Table Size approx. 17600 routes.• cf. HAWAII with 140 ARs (BSs) has 38,720 mobile host routes per domain router

Route Table Size

0 10000 20000 30000 40000 50000

Access Router

Edge Router

Inter. Router

Core Router

Domain Router (HAWAII)

Route

r Type

Number of Routes

AR (subnet) Routes

Mobile Host Routes

(for 140 ARs)

(for 1600 ARs)

Domain Router

edge mobility architecture

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