connection oriented mobility using edge point interactivity

Connection Oriented Mobility Using Edge Point

Interactivity

Sandeep DavuNetworking and Media Communications Research

LaboratoriesComputer Science Department

Kent State University

AGENDA

• Problem Statement

• Related Work

• Proposed Scheme -- IPMN

• Implementation 2-Layer IPMN

• Performance Analysis

• Modeling of 3-Layer IPMN

• Conclusion

AGENDA

• Problem Statement– Mobility Management– Short Comings of current network– More higher layer specific approach needed

• Related Work

• Proposed Scheme


• Conclusion

Mobility Management • A node is said to be mobile if its point of attachment is flexible within

and across networks.• Handoff is the process of changing the point of attachment without

losing the connection states.• Handoff classifies into two categories.

– L2 handoff –only the point of attachment in LL is required (change of Access Point).

– L3 handoff—happens along with L2 handoff where Access Point is in a different subnet. This requires attaining new IP address.

Router Router

Backbone Network

Corresponding Node

Mobile Node

AP3

IP-Subnet 1 IP-Subnet 2

AP4 AP1 AP2

Mobile Node Mobile Node

L2 HandoffL3 Handoff

IP1 IP1 IP2

Short comings of network

• OS and network architecture did not envision wireless and mobility.• Error Prone nature of the wireless links – not as rigid as Ethernet.• State full nature of connection oriented networks – robust

retransmissions.• A transport layer connection is identified by a four tuple <source

address, source port, destination address, destination port> maintained at either end points.

• A L3 handoff requires a network address change for the Mobile Node rendering the current TCP connection useless.

• Unexpected disconnections and moving end points.• Rapidly Converging 3G and 4G networks and strong need to have

seamless mobility• Is there an effective way to handle this???

Protocol Re-organization

• Principle – Most network complexities are better handled at higher layers and end-systems.

• Protocol extension needed for mobility and justifies the design principle employed.

• Mobility in wireless networks (802.11 MAC) involves more than one network layer to perform a handoff.

• cross-layer interaction between networking layers to achieve high performance loss-free handoffs.

• Event based approach with no timer latencies to kick off actions.

Are current approaches not enough???

• There are several approaches proposed which address one particular area of mobility

• Solutions proposed in one layer (either IP or TCP).• Interoperability between layers was hindered.• Indirect performance implications even if the problem was

addressed directly.

AGENDA


• Related Work– Network Layer Solutions– Higher Layer Solutions

• Mobility Management• Performance Tuning

• Proposed Scheme


• Conclusion

Network Layer Solutions

• Mobile IP provided the first effective crack in handling mobility.

• Route Optimization provides a solution for triangulation problem.

• Hint based handoffs used triggers from lower layers as hints to perform fast handoff.

• The RAT (Reverse Address Translation) architecture, based on the network address translation (NAT) protocol, uses packet re-direction service between CH and MN to support IP mobility.

Mobile IP• Added an indirection to the routing mechanism in the

form of Home Agents and Foreign Agents.• Mobile IP Handoff is a two step process

– Movement Detection—Detects which Agent will service the MN.– Registration—Registers the Foreign Agent with Home Agent.– Tunneling—HA and FA creates a mutual tunnel to route packets

to MN.

Mobile Node

Home Agent

Foreign Agent

Correspondent Node

LL

Probe SNR

LL

Assoc

MIP

Movement

MIP

TCP

AA AALT timerCOA Tunneling

LL

MIP

Tunneling IP-COA

TCP

IP

LL

Mobile NodeHome Agent

Old Foreign agent

Correspondent Host

Beacon timerBeacon Assoc

t

t

Mobile IP Movement Detection

LL

Probe Auth Assoc

LL

Auth Assoc

MIP

Registration

MIP

TCP

AA MovementCOA Tunneling

LL

MIP

Tunneling IP-COA

TCP

IP

LL

RT timer Congestion

Mobile NodeHome Agent

New Foreign agent

Corresponding Host

RT timer Congestion

Beacon

tt

Mobile IP Registration and Tunneling

Higher Level Solutions

• Split Connection Approach– I-TCP was a split approach to the end-to-end

connection where the connection was split at the Base Station or Access Point.

– MSOCKS[8] achieves connection redirection using split connection proxy.

• End-to-End Approach– TCP-R is based on an idea- same as ours, renewing

the connection to handle the new IP address.

• Performance Tuning– Freeze TCP freezes the connection during the course

of a handoff by advertising a zero window at the MN.

AGENDA

• Problem Statement• Related Work• Network Layer Solutions• Proposed Scheme

– IPMN Architecture– 2 Layer implementation (experiment and

performance)

Performance Analysis

IPMN 3-Layer Modeling

• Conclusion

Our Scheme• Uses rapid cross layer interactivity to provide high

performance connection oriented mobility support.• Based on the Interactive Transparent Networking

(InTraN) paradigm – focused on ordered cross layer interactivity, developed recently in the MediaNet Lab.

• Interactive Protocol for Mobile Networks (IPMN) allows event based access to protocol states even by network layer processes or even by L7 processes.

• This mobility solution does not require any functional change in the classical TCP/IP network, can avoid FA or HA (thus the need of an infrastructure!), can avoid triangulation, is loss-free, and above all offer much faster handoff.

Interactive Transparent Networking

6a

3b

3a

user space

1

7

TCP kernel

2

4a

Event Information

ConnectionState

Application

Probing APISubscription API

T-ware (2)

TCP Connection

system

Kernel

5

Signal Handler

4b 6b

T-ware (1)

T-ware (n)

Event Monitor

Socket API

Interactive protocol for Mobile networks

• Event based approach trapping handoff related events—mostly at L2 like probing, authentication, association.

• Probes the link layer and intelligently performs a handoff based on information from L2.

• Handoff procedure depends on the cell boundary conditions of the Access Points.– Overlapping – When a MN is being serviced by more than one

AP at any given point of time – Non-overlapping – When MN is experiencing temporary periods

of disconnections when switching between AP’s.

• Does not require an infrastructure – easy to deploy, backward compatible to legacy networks.

LL

Probe Auth Assoc

LL

Auth Assoc

IP

TCP

TCP

IP

LL

PR timer

Mobile Node

Future Access Point

Correspondent Host

0 win

Beacon

t

Application

Freeze Handler

Auth Handler

RealyIP Handler

Application

OPT=SWITCHIP

src_addr

OPT=SWITCHIP

Application

SwitchIP Handler

dst_addr

ACK ‘OPT’

Unfreeze Handler

Non 0 win

1

3

4

2

Trns timer

Handoff in an overlapping cell boundary

LL

SNR

Application

Old Access Point

t

Interactive Protocol for Mobile Networks(2- layer Implementation)

Node

Event

Layer Event tracked Action taken by event handler

Mo

bile

No

de

1 LLL2 handoff has been initiated.

Advertises a zero window to the FH. The freeze mechanism of TCP will force the FH to stop transmission.

2 IPA new IP has been assigned to the MN from the future BS.

Call the switch_ip() system call. This will replace the source IP filed in the IP header of the MN with the new IP and will send a segment to the FH with TCP option = SWITCH_IP to replace the destination IP field on the FH.

3TCP

The ‘SWITCH_IP’ segment has been ACKed.

Advertises a non-zero window to the FH. This will unfreeze the connection and enable the FH to resume transmission.

Fixe

d H

ost

4TCP

A special TCP segment received with TCP option=SWITCH_IP.

Strip the new IP number from the options part of the segment, then call the switch_IP() system call which stores the new IP in the destination IP field of the IP header overwriting the old IP number.

LL

Probe Auth Assoc

LL

Auth Assoc

IP

TCP

TCP

IP

LL

PR timer

Mobile Node

Future Access Point

Correspondent Host

0 win

Beacon

Application

Freeze Handler

Auth Handler

RealyIP Handler

Application

OPT=SWITCHIP

src_addr

OPT=SWITCHIP

Application

SwitchIP Handler

dst_addr

ACK ‘OPT’

WakeUp Handler

Non 0 win

1

3

4

5

Trns timer

Handoff in an non-overlapping cell boundary

Freeze

Pro

be B

ou

nd

ary con

ditio

n

Get N

ewIP

Sw

itch S

ou

rceIP

WakeU

p

Sw

itch

Des

tIP

New IP


• Implementation of L4-L7 cross layer interactivity.• Experimented with the manipulation of IP addresses to

reflect the address change.• Implemented changes to the kernel on a FreeBSD4.5

OS running on 700MHz Intel Pentium 4 processor.• API calls for subscribing to events and t-ware

modifications to the kernel.• Experiments were carried out between different sites

(varying geographic distances)


Table-2 API Extesnion

AGENDA

• Problem Statement• Related Work• Network Layer Solutions• Proposed Scheme• Performance Analysis

– Experiment Setup– Performance results

• Modeling 3-Layer Handoff.• Conclusion

Experiment Setup

BS1

MobileNode

CorrespondentNode Gateway

Switch

BS2 BS3

InternetLab setup consisted of a Mobile Node a switch and three Base station machines running FreeBSD4.5 OS and a gateway to connect to the outside world.

Handoff was simulated using the switch unplugging already plugged in BS and plugging in the new BS. MN is always connected to the switch.

Three scenarios where we performed the experiments– varying the position of the Correspondent Node each time– locally in the lab, in Texas and in Virginia.

The CN generated voice traffic based on the NetSpec Source Models . We also let the MN move along the cyclic path handoff occuring every 2 minutes BS1→BS2→BS3→BS2→BS1

Node name

Location IP numberAverage

RTT

Hops from MN

LocalKent, Ohio

131.123.36.11 1 ms 3

VirginiaChantilly

, VA66.94.95.236 90 ms 19

TexasHuston, Texas

70.241.64.99 183 ms 26

Voice

0

500

1000

1500

2000

2500

3000

1 11 21 31 41 51 61 71

Call Arrival Distribution

Call number

Interarrival time (ms)

0

5

10

15

20

25

30

1 11 21 31 41 51 61

L1 = 0.004168

L2 = 0.003334

L3 = 0.002778

Call Duration Distribution

Call number

Duration (min)

• voice has been characterized by a constant bit rate (CBR) source. Sampling rate is 8 kHz and each sample is 8 bits. This gives the standard bit rate of 64 Kb/sec for acceptable voice quality.

• Inter-arrival time between two calls is exponentially distributed.

• To generate a 64 Kb/sec voice stream, talk bursts were generated by a 144-byte blocks separated by 18 ms silence periods.

Performance Results• After running the experiment several times on the three nodes we

have observed a big difference –up to two orders of magnitude—in handoff latency between IPMN and classic MIP.

• IPMN managed to perform handoff in 110 to 200 milliseconds on average while MIP needed between 14 to 44 seconds.

• substantial reduction in handoff latency highlights the advantage of event-based protocols like IPMN over timer-based protocols like MIP.

• Demonstrates the property by comparing the handoff latencies of the first 5 handoffs at the application level and at the MIP level.

TABLE-4. HANDOFF LATENCIES (IN MS) OF THE FIRST FIVE HANDOFFS

Local Virginia Texas Handoff

IPMN MIP IPMN MIP IPMN MIP 1 106 12654 114 58669 202 51359 2 107 7124 106 24975 193 33187 3 111 1524 106 22672 195 29099 4 115 48945 111 77414 195 63523 5 109 1008 121 30772 200 41676

Average 110 14251 112 42900 197 43769

0

20

40

60

80

1 2 3 4 5

0

20

40

60

80

100

1 2 3 4 5

0

20

40

60

80

100

1 2 3 4 5

MIP level latency

Application level latency

(a) Local node

Handoff

Latency (seconds)

(b) Virginia node

Handoff

(c) Texas node

Handoff

Performance Results

• Comparing the overhead of MIP and Application.• Application cannot immediately recover as soon as handoff is

completed.• Strong Reason to have application aware network solutions for

smoother transitions.

Performance Results

0

50

100

150

200

250

300

1 5001 10001 15001 20001

IPMN MIP

(b) Virginia Node

Arrival time (seconds)

Block number

0

200

400

600

800

1 5001 10001 15001 20001

IPMN MIP

Arrival time (seconds)

Block number

(a) Texas Node

10

30

50

70

90

110

130

150

1 3001 6001 9001 12001 15001

10

30

50

70

90

110

130

150

1 3001 6001 9001 12001 15001

(a) IPMN Jitter

Block number


(b) MIP Jitter

Block number


Performance Results

1000

10000

100000

1000000

10000000

1 21 41 61 81 101

Alpha1=0.4Alpha2=0.55

Document Size Distribution

Document number

Document Size (bytes)

0

1000

2000

3000

4000

5000

1 21 41 61 81 101

Lam1=0.000001Lam2=0.000005

Document size distribution of the first 100 documents. Interarrival times of the first 100 documents.

xX exf )(

mean/1,

x

kxFX 1)(

21

63.04.0

k

1)( xkxf X

Performance Results

Figure-7. Traffic arrival at the MN at the two nodes for two values of λ. Handoff occurrences at both MIP and IPMN are marked on the fragment number of each plot.

Traffic arrival at MN with handoff markedLocal node - Lambda=0.00005

0200000

400000600000

800000

1 5001 10001 15001 20001 25001 30001

Message number

Arr

ival

Tim

e (m

s)

IPMNIPMN HandoffMIPMIP Handoff

Traffic Arrival at MN with handoff Local Node with λ = 0.000005

Traffic Arrival At MN with HandoffLocal node - Lambda=0.00001

0200000

400000600000

800000

1 5001 10001 15001 20001 25001 30001

Message number

Arr

ival

Tim

e (m

s)


Traffic Arrival at MN with handoff Local Node with λ = 0.000001

Traffic arrival at MN with handoff markedAl-Quds node - Lambda=0.00001

0500000

10000001500000

2000000

1 2001 4001 6001 8001 10001

Message number

Arr

ival

Tim

e (m

s)


Traffic Arrival at MN with handoff Al-Quds Node with λ = 0.000001

Traffic arrival at MN with handoff markedAl-Quds node - Lambda=0.00005

0500000

10000001500000

2000000

1 2001 4001 6001 8001 10001Message number

Arr

ival

tim

e (m

s)


Traffic Arrival at MN with handoff Al-Quds Node with λ = 0.000005

AGENDA


• Related Work

• Network Layer Solutions

• Proposed Scheme


• Modeling 3-Layer Handoff


• Conclusion

IPMN 3-Layer Handoff• IPMN has L2 and L3 handoffs.• We considered 802.11 as the MAC and modeled the

handoff based on 802.11.• TCP based implementation earlier has given enough

insight to model the L3 handoff.• Closely observing we found it controlled properly there

are some phases in L2 and L3 Handoffs that could be done in parallel.

• Events from L2 triggers actions in L3.• Allowing direct access between layer would be a chaos.• Allowing application intervention is the cleanest way for

decision making and controlled cross-layer interaction.

Modeling 3-layer IPMN

• Divided into two layers– L2 802.11 Handoff– L3 Handoff.

• L2 handoff– Probing – Time to Scan the channels and identify a channel that

can be used.– Authentication – Once the channel is established the useability

of the channel is verified.– Association – The MN will be associated with the Access Point

when the state information is transferred from old to new access point.

• L3 handoff– Based on the previous experiments ….event notification and t-

ware overheads...

L2 handoff model for 802.11

• Link Layer Latency– Probing

– Authentication

– Association/Re-Association

eud TeTuS **

TimeMinChannelTT

TimeMaxChannelTT

de

du

*2

*2

))(*2(*))(*2(*00

TimeMinChanneldttfeTimeMaxChanneldttfuS ttd

n

iTatd unWherePdttfA

1 0

1)(

Trtd PdttfRA

0

)(*2

L2 Handoff model for 802.11

• Link Layer Latency– Probing (Scan delay)

u + e = number of channels – 802.11 has 11-16 channels

Tu : Time Spent in used channel + probe RTT

Te : Time Spent in empty channel + probe RTT

Td : Time For probe transmission

ft (t) : characteristic of the channel as a factor of time

BER … Transmission rate …

eud TeTuS **

TimeMinChannelTT

TimeMaxChannelTT

de

du

*2

*2

0

)( dttfT td


• Probing Delay– Total Probing delay

– Most of the Time spent in a L2 Handoff is in probing.

– There are many techniques in L2 Handoff itself to speed up Probing for overall better Handoff.

))(*2(*))(*2(*00

TimeMinChanneldttfeTimeMaxChanneldttfuS ttd


• Authentication– Each successfully scanned channel is tried for authentication until a

channel is authenticated.

Td : Time For probe transmission

PTa: Authentication Time

n : Total Number of tries –one per channel until authentication is succeeded.

i : Channel Number that is being authenticated

n

iTadd unWherePTA

1

1*2


• Association/Reassociation– After successful authentication the MN’s state information is transferred

from the old AP to new Access Point.

– Re-association is helpful in knowing the current attachment point of the MN as it is moving from old Access Point to new Access Point.

Td : Time For transmission

PTr: Time for state information exchange between Access Points after successful Authentication of that channel

Trdd PTRA *2

Modeling IPMN

• Higher Layer Latency– Signaling Overhead – Time Taken for event notification – Event Handler Overhead – Time Taken by t-ware modules to access

event information and/or any internal stored information

– Attaining IP address – Application level overhead to get the IP address

Events Tracked

Table 8: Events for IPMN

Ack for TCP_OPTION=SWITCHIP

Recv TCP_OPTION=SWITCHIPTCP Layer

IP address changeIP Layer

Successful Authentication

Successful Probing Link Layer

EventsLayer

Table 8: Events for IPMN

Ack for TCP_OPTION=SWITCHIP

Recv TCP_OPTION=SWITCHIPTCP Layer

IP address changeIP Layer

Successful Authentication

Successful Probing Link Layer

EventsLayer

Modeling IPMN

• Higher Layer Latencysignaling overhead

Event Handler overhead

Attaining IP Address

PRd: proactive registration delay for getting an IP address.

10010 XwheresXSycd

205 YwheresYTg d

dd TPR 1*2


• Modeled the total IPMN handoff scheme using statistical modeling.• Incorporated the L2 delay as a statistical model and all the signaling

delays and the system call delays as constants.• Also modeled Mobile IP’s handoff to have better performance

analysis.


MN

AP TCP LL

CH

AP TCP LL

new AP

AP LL

Pr req 1

Pr req n

Pr res 1

Pr res nE1

Freeze

Auth req

E2 Re-Asso req

Auth res

Re-Asso res

NewIP req

NewIP res

Relay IP

ACK Relay IP

Wake Up

(a) Overlapping Cell Boundary

E3

Modeling 3-layer IPMN MN

AP TCP LL

CH

AP TCP LL

new AP

AP LL

Pr req 1

Pr req n

Pr res 1

Pr res nE1

Freeze

Auth req

Re-Asso req

Auth res

Re-Asso res

Relay IP

ACK Relay IP

Wake Up

(b) Non-Overlapping Cell Boundary

E3

E5

Modeling IPMN

• Total IPMN Handoff Delay for overlapping boundary conditions

• Total IPMN Handoff Delay for non-overlapping boundary conditions

dddddddddd SycEpPRSycRATgSycATgST *3,max*2,max0

ddddddddddn SycEpPRSycRATgSycATgST *4,*2,max0

Modeling MIP

• MIP Handoff consists– Movement Detection

– Registration

– Tunneling

• MIP Handoff consists

ddd NxTxM 21 *2

2*2 dd TR

dd ITTu *2

ddddd ITRMLH

Extensions-performance analysis

• Both MIP and IPMN handoffs are simulated using the developed models.

• Performed 100 handoffs and averaged them for both overlapping and non-overlapping scenarios in either case.

• IPMN had an average handoff delay of only 70ms while MIP had an average delay of 1.37s in overlapping and 1.6s and 2.14s in non-

overlapping scenario. Handoff Latencies

IPMN

IPMN

MIP1

MIP1

MIP2

MIP2

01

23

1 2cell boundaries

tim

e (s

ecs)

IPMN

MIP1

MIP2

MIP1 and MIP2 are versions of MIP with an AA lifetime of 100ms and 1s respectively.

MIP2 is the proposed practice.

MIP1 though seems to have lower handoff delay it imposes a lot of communication overhead monopolizing the bandwidth

Extensions-performance analysis

• IPMN always stays closer to No handoff case which has delay only due to BER and congestion--Normal TCP flow if the MN were not shifting cells.

• MIP lags behind by approximately 10s delivering voice traffic and 15s in delivering WWW traffic.

• Minimal handoff transition delay for IPMN provides seamless connection.

AGENDA


• Related Work

• Network Layer Solutions

• Proposed Scheme


• Modeling 3 layer IPMN

• Conclusion

Conclusion

• We have presented high performance mobility protocol which uses rapid cross layer interactivity.

• Eliminates routing indirection (triangulation) by explicitly specifying the application about the underlying network change.

• Flexibly manipulating the underlying network states transparently from L7 to reflect network address changes—thus eliminating the L3 movement detection.

• MIP’s timer based rediscovery of already existing state information in lower layers makes it sluggish.

• Our scheme uses this and other information from lower layers to intelligently perform handoff– proactive or reactive.

Conclusion

• Most interesting claim- solution is based on L7 disposable transientware processes.

• Demonstrated in this case one possible intelligent schema for high performance TCP/IP mobility handling.

• Further improvements and replacements by more powerful schemes are easy to incorporate– flexibility of L7 transientware.

• Demonstrated mobility solution did not require any functional change in classical TCP/IP layers.

• Performance Results indicate the effectiveness and efficiency of our even-based scheme.

connection oriented mobility using edge point interactivity

Documents

higher layer support

transport layer connection

fast handoff

point of attachment

crosslayer interaction

connection oriented

lower layers

network address change