Proposed ad hoc Routing Approaches

Proposed ad hoc Routing Approaches• Conventional wired-type schemes (global

routing, proactive):– Distance Vector; Link State

• Proactive ad hoc routing:– OLSR, TBRPF

• On- Demand, reactive routing:– DSR (Source routing), MSR – AODV (Backward learning)

• Scalable routing :– Hierarchical routing: HSR, Fisheye– OLSR + Fisheye– LANMAR (for teams/swarms)

• Geo-routing: GPSR, GeRaF, etc– Motion assisted routing– Direction Forwarding

Where do we stand?

• OLSR and TBRPF can dramatically reduce the “state” sent out on update messages

• They are very effective in “dense” networks.

• However, the state still grows with O(N)• Neither of the above schemes can handle

large scale nets from 10’s to thousands of nodes

• What to do?

The previous schemes reduce control traffic O/H but do not significantly reduce routing table size

Solution: use hierarchical routing to reduce table size

In the process, reduce also control traffic O/HProposed hierarchical schemes include:

– Hierarchical State Routing (HSR)– Fisheye State Routing (FSR)– Landmark Routing – Zone routing (hybrid scheme)

Hierarchical Routing

Hierarchical State Routing (HSR)

• Loose hierarchical routing in Internet• Main challenge in ad hoc nets: maintain/update the

hierarchical partitions in the face of mobility• Solution: distinguish between “physical” partitions

and “logical” grouping– physical partitions are based on geographical

proximity– logical grouping is based on functional affinity

between nodes (e.g., tanks of same battalion, students of same class)

• Physical partitions enable reduction of routing overhead

• Logical groupings enable efficient location management strategies using Home Agent concepts

HSR - physical multilevel partitions

Level = 0

5

1

7

6

11

4

23

10

98

1

23

4 Level = 1

1 3Level = 2

DestID

1

6

7

<1-2->

<1-4->

<1-3>

Path

5-1

5-1-6

5-7

5-1-6

5-7

5-7

HSR table at node 5:

HID(5): <1-1-5>

HID(6): <3-2-6>(MAC addresses)

Hierarchical addresses

HSR - logical partitions and location management

• Logical (IP like) type address <subnet,host>– Each subnet corresponds to a particular user

group (e.g., tank battalion in the battlefield, search team in a search and rescue operation, etc)

– logical subnet spans several physical clusters

– Nodes in same subnet tend to have common mobility characteristic (i.e., locality)

– logical address is totally distinct from MAC address

HSR - logical partitions and location management (cont’d)

• Each subnetwork has at least one Home Agent to manage membership

• Each member of the subnet registers its own hierarchical address with Home Agent – periodical/event driven registration; stale

addresses are timed out by Home Agent• Home Agent hierarchical addresses

propagated via routing tables; or queried at a Name Server

• After the source learns the destination’s hierarchical address, it uses it in future packets

• Example: Landmark Routing

Scope of Fisheye

1

2

3

4

5

67

8

9

9

10

11

12

14 1516 17

18 19

20

21

2223

2425

26

27

28

29

30

31

3234

35

36

Hop=1

Hop=2

Hop>2

13

1

2

3

4

5

67

8

9

9

10

11

12

14 1516 17

18 19

20

21

2223

2425

26

27

28

29

30

31

3234

35

36

Hop=1

Hop=2

Hop>2

13

1

2

3

4

5

67

8

9

9

10

11

12

14 1516 17

18 19

20

21

2223

2425

26

27

28

29

30

31

3234

35

36

Hop=1

Hop=2

Hop>2

13

Fisheye State Routing (FSR)

Fisheye State Routing (FSR)• Topology data base at each node

- similar to link state (e.g., OSPF)• Routing information is periodically exchanged with

neighbors only ( “Global” State Routing)– similar to distance vector, but exchange entire

topology matrix• Routing update frequency decreases with distance

to destination – Higher frequency updates within a close zone

and lower frequency updates to a remote zone– Highly accurate routing information about the

immediate neighborhood of a node; progressively less detail for areas further away from the node

Message Reduction in FSR TC (Topology Control) message

0

5

1

2

4

3

0:{1}1:{0,2,3}2:{5,1,4}3:{1,4}4:{5,2,3}5:{2,4}

101122

LST HOP

0:{1}1:{0,2,3}2:{5,1,4}3:{1,4}4:{5,2,3}5:{2,4}

212012

LST HOP

0:{1}1:{0,2,3}2:{5,1,4}3:{1,4}4:{5,2,3}5:{2,4}

321101

LST HOP

Optimized “Fisheye” Link State Routing (OFLSR)

• Based on Optimized Link State Routing (OLSR)• Borrows idea from Fisheye State Routing (FSR)• Different frequencies for propagating the Topology

Control (TC) message of OLSR to different scopes (e.g. different hops away)

scope 1

scope 2

scope 3

scope 4

scope w idth

Scalability Property of OFLSR

• Scalability to Node Mobility– 100 nodes, 1600mX1600m field, 367m Tx range– IEEE 802.11 radio, 2Mbps channel rate, 10 CBR flows– OLSR confign: hello interval = 1s, TC interval = 2s– OFLSR confign: 4 scopes, each scope is 2 hops

except last one

00. 10. 20. 30. 40. 50. 60. 70. 80. 9

1

0 5 10 15 20

OLSROLSR + FSR (scope)OLSR + FSR (probabi l i ty)

Dat

a P

acke

t D

eliv

ery

Rat

io

Node mobility speed (m/s)

Data Packet Delivery Ratio


• Scalability to Node Mobility

Total # of TC relayed

050000

100000150000200000250000300000350000400000450000500000

0 5 10 15 20

Node Mobi l i ty (m/ s)

# of T

C mess

ages r

elayed

OLSROLSR + FSR (scope)OLSR + FSR (probabi l i ty) 0

1000000200000030000004000000

50000006000000700000080000009000000

0 5 10 15 20

node mobi l i ty (m/ s)

TC mes

sage r

eceive

d

OLSROLSR + FSR (scope)OLSR + FSR (probabi l i ty)

Total # of TC received

00. 10. 20. 30. 40. 50. 60. 70. 80. 9

1

100 200 300 400 500

OLSROLSR + FSR


• Scalability to Network Size– Keep node density, increase # of nodes, no mobility– OLSR confign: hello interval = 2S, TC interval = 4S– OFLSR confign: 4 scopes, each scope is 2 hops

except last one

Dat

a P

acke

t D

eliv

ery

Rat

io

Network Size (# of nodes)

Delivery rate vs Network Size


• Scalability to Network Size

Total # of TC relayed Total # of TC received

0

1000000

2000000

3000000

4000000

5000000

6000000

100 200 300 400 500

Network Si ze (# of nodes)

# of T

C rela

yed

OLSROLSR + FSR

0

10000000

20000000

30000000

40000000

50000000

60000000

100 200 300 400 500

Network Si ze (# of nodes)

# of T

C rece

ived

OLSROLSR + FSR

Scalable Ad Hoc Routing using Landmarks and Backbones

• The challenge– Tens of thousands of nodes– Nodes move in various patterns– QoS communications requirements– Hostile environment – jamming

Routing

• Current MANET solutions have limitations: – (a) proactive routing solutions (eg, Optimal

Links State -OLSR) do not scale because of table size and control traffic overhead

– (b) on demand routing cannot handle high mobility and dense traffic patterns

– (c) explicit hierarchical routing introduces excessive address maintenance O/H in high mobility

• MANET protocols do not scale in high mobility• Our approach:

– Exploit implicit hierarchy induced by group mobility

Solution: Landmark Routing Overlay

• Main assumption: nodes move in groups (battlefield)

• Groups are predefined or dynamically recognized

• Node address: < group ID , Host address>• Landmark elected in each group• Landmarks advertisements maintain the

landmark overlay

Logical Logical SubnetSubnet

LandmarkLandmark

LANMAR Overlay Routing (cont)

• Builds upon existing MANET protocols– (1) “local ” routing algorithm that keeps

accurate routes within local scope < k hops (e.g., OLSR)

– (2) Landmark routes advertised to all mobiles using DSDV

– Like Internet: LS + DV

Logical SubnetLogical Subnet

LandmarkLandmark

LANMAR Overlay Routing (cont)• Packet Forwarding:

– A packet to “local” destination is routed directly using local tables

– A packet to remote destination is routed to Landmark corresponding to logical addr.

– Once the landmark is “in sight”, the direct route to destination is found in local tables

• Benefits: low storage, low update traffic O/H


LandmarkLandmark

Landmark Routing In action


LandmarkLandmarkLM1 LM2

LM3

sourcesourcedestdest

Long haul routinglocal routing

1. Node address = {subnet ID, Host ID}2. Look up local routing table to locate dest fail3. Look up landmark table to find destination subnet

LM14. Send a packet toward LM1

Link Overhead of LANMAR• Dramatic O/H reduction from linear to O(N) to O (sqrtN)

LANMAR: Local Scope Optimization• Goal: find local routing scope size that minimizes

routing overhead– size of landmark distance vector: O ( N / G)– size of local Link State topology map: O ( m * d ) N: total # of nodes; d: avg # of one-hop neighbors (degree)

)2

(dh

NlmH

10),2( 1 dhlocalH

locallm HHH

H (

Ro

uti

ng

ov

erh

ea

d)

h (scope size)

*h

Total O/H

Landmark O/H

Local route O/H

LANMAR enhances MANET routing schemes

We compare:

(a) MANET routing schemes: DSDV, OLSR and FSR; and

(b) same MANET schemes, BUT with LANMAR overlay on top

Delivery Ratio

• DSDV and FSR decrease quickly when number of nodes increases• OLSR generates excessive control packets, cannot exceed 400 nodes

OLSR

DSDV

FSR

LANMAR-DSDV

LANMAR-OLSR

LANMAR-FSR

Mobile Backbone Overlay

• Landmark Overlay provides routing scalability

• However the network is still flat - paths have many hops poor TCP and QoS performance!!

• Solution: Mobile Backbone Overlay (MBO)• MBO is a physical overlay – ie long links• MBO provides performance scalability• LANMAR extends “transparently” to the

MBO

Backbone NodeBackbone Node


LandmarkLandmark

sourcsourcee

destdest..

UAUAVV

Landmark routing concept extends transparently to the multilevel backbone

Fast BB links are “advertised” and immediately used

When BB link fails, the many hop alternate path is chosen

Backbone Network and LANMAR• Why a Backbone “physical” hierarchy?

– To improve coverage, scalability and reduce hop delays

• Backbone deployment– automatic placement: Relocate backbone

nodes from dense to sparse regions (using repulsive forces)

• Key result: LANMAR automatically adjusts to Backbone

• Combines low routing O/H (LANMARK logical hierarchy) + low hop distance and high bandwidth (Backbone physical hierarchy)

Extending Landmark to Hierarchical Network

• Backbone nodes are independently elected

• All nodes (including backbone nodes) are running the original LANMAR

• In addition, backbone nodes re-broadcast landmark information via higher level links

• Backbone Routes preferred by landmark (they are typically shorter)

Extending Landmark (cont)• If backbone node is lost, Landmark routing

“fills the gap” while a replacement backbone node is elected

• Advantages– Seamless integration of “flat” ad hoc

landmark routing with the backbone environment provides instant backup in case of failures

– Easy deployment, simple changes to ordinary ground nodes

– Remove limitations of strictly hierarchical routing

Variable number of Backbone Nodes• Decrease of average end-to-end delay while increasing # of

backbone nodes

0

10

20

30

40

50

60

0 9 18 27 36

# of backbone nodes

Averag

e e

nd

-en

d d

ela

y(sec)

Hierarchical Landmark

Flat Landmark

Variable number of Backbone Nodes• Increase of delivery fraction while increasing # of

backbone nodes

0.5

0.6

0.7

0.8

0.9

1

0 9 18 27 36

# of backbone nodes

Delivery

Fra

cti

on


Flat Landmark

Variable Speed with 1000 nodes

Delivery fraction while increasing mobility speed

0.4

0.5

0.6

0.7

0.8

0.9

1

1.1

0 2 4 6 8 10

Mobility speed(m/sec)

Delivery

fra

cti

on


Flat Landmark

AODV

LANMAR implementation in IPv6 LINUX environment

• Use IPv6’s Group ID to distinguish groups• Support many more members in each group

(than IPv4)

• A packet to remote destination is routed to corresponding Landmark based on IPv6 address lookup

IPv6: 48 bits 16 bits 64 bits

GroupID Node IDNetwork ID

SubnetMask 0000 … 000 11…11 00000000 … 0000000

Documents

Proposed ad hoc Routing Approaches