Using Directionality in Wireless Routing
Bow-Nan Cheng
Advisors:
Dr. Shivkumar Kalyanaraman
Dr. Partha Dutta
1
Motivation
Infrastructure / Wireless Mesh
Networks
• Characteristics: Fixed, unlimited energy,
virtually unlimited processing power
• Dynamism – Link Quality
• Optimize – High throughput, low latency,
balanced load
Mobile Adhoc Networks
(MANET)
• Characteristics: Mobile,
limited energy
• Dynamism – Node mobility
+ Link Quality
• Optimize – Reachability
Sensor Networks
Main Issue: Scalability
Introduction
Wireless Mesh Networks
• Characteristics: Data-Centric,
extreme limited energy
• Dynamism – Node State/Status
(on/off)
• Optimize – Power consumption
Mobile Ad-Hoc Networks
Overlay Networks
2
Scaling Networks: OSI Model
Transport Layer – Handles reliable transmissions end-to-end
Network Layer – Manages routing from end-to-end
Layers 5-7
C
F
4: Transport Layer
A
3: Network Layer
A
2: Link Layer
B
Z
E
G
Z
H
Link Layer – Manages node-to-node transmissions
1: Physical Layer
1011010
Physical Layer – Handles transmission of bits through a medium
Application/Presentation/Session Layers – Deal with the actual programs/data
Introduction
Wireless Mesh Networks
Mobile Ad-Hoc Networks
Overlay Networks
3
Scaling Networks: Trends in Layer 3
Flood-based
Mobile Ad hoc /
Fixed Wireless
Networks
DSR, AODV,
TORA, DSDV
Partial Flood:
OLSR, HSLS
Peer to Peer /
Gnutella
Overlay Networks
Wired Networks
Introduction
Ethernet
Hierarchy/Structured
Unstructured/Flat
Scalable
LGF, VRR, GPSR+GLS
Hierarchical Routing,
WSR (Mobicom 07)
ORRP (ICNP 06)
Kazaa, DHT Approaches:
CHORD, CAN
BubbleStorm (Sigcomm 07)
LMS (PODC 05)
Routers (between AS)
SEIZE
Wireless Mesh Networks
Mobile Ad-Hoc Networks
Overlay Networks
4
Trends: Directional Antennas
B’
B’
B
A
A’
B
D’
A
D
C
A’
C’
Omni-directional Transmission
•
D’
D
C
C’
Directional Transmission
Directional Antennas – Capacity Benefits
 Theoretical Capacity Improvements - factor of 4p2/sqrt(ab)
where a and b are the spreads of the sending and receiving
transceiver ~ 50x capacity with 8 Interfaces (Yi et al., 2005)
 Sector Antennas in Cell Base Stations – Even only 3 sectors
increases capacity by 1.714 (Rappaport, 2006)
 Directional Antennas – Simulations show 2-3X more capacity
(Choudhury et al., 2003)
Introduction
Wireless Mesh Networks
Mobile Ad-Hoc Networks
Overlay Networks
5
Trends: Hybrid FSO/THz FSO/RF MANETs
•
Current RF-based Ad Hoc Networks:




802.1x with omni-directional RF
antennas
High-power – typically the most power
consuming parts of laptops
Low bandwidth – typically the
bottleneck link in the chain
Free-Space-Optical
(FSO) Communications
Error-prone, high losses
• High bandwidth
• Low power
• Dense spatial reuse
• License-free band of
operation
Mobile Ad Hoc
Networking
• Mobile communication
• Auto-configuration
Free-Space-Optical
Ad Hoc Networks
• Spatial reuse and angular diversity in nodes
• Low power and secure
• Electronic auto-alignment
• Optical auto-configuration (switching, routing)
• Interdisciplinary, cross-layer design
Introduction
Wireless Mesh Networks
Mobile Ad-Hoc Networks
Overlay Networks
6
Research Objectives
• Wireless Mesh Context
 Can directionality be used to address issues with
scalability at higher throughput in layer 3
routing?
• Mobile Ad Hoc Context
 Can directionality be used to address issues with
high mobility and throughput in layer 3 routing?
• Overlay Network Context
 Can directionality be used to scale flat,
unstructured networks?
Introduction
Wireless Mesh Networks
Mobile Ad-Hoc Networks
Overlay Networks
7
Orthogonal Rendezvous Routing Protocol
?
N
(4,6)
S D(X,Y)?
(0,4)
W
D
(8,5)
(15,5)
(12,3)
(5,1)
E
S
By removing
position
information, can
we still efficiently
route packets?
Issues in Position-based Schemes
L3: Geographic Routing using Node IDs
(eg. GPSR, TBF etc.)
ORRP
L2: ID to Location Mapping
(eg. GHT, GLS etc.)
N/A
L1: Node Localization
Introduction
Wireless Mesh Networks
Mobile Ad-Hoc Networks
Overlay Networks
8
Orthogonal Rendezvous
Routing Protocol
ORRP Big Picture
ORRP Primitive
1: Local sense of direction
leads to ability to forward
packets in opposite
directions
A
180o
S
98%
T
Up to 69%
B
2: Forwarding along
Orthogonal lines has
a high chance of
intersection in area
Introduction
Wireless Mesh Networks
Mobile Ad-Hoc Networks
Overlay Networks
9
ORRP Design Considerations
• Considerations:
 High probability of connectivity without position
information [Reachability]
 Scalability O(N3/2) total state information maintained.
(O(N1/2) per node state information)
 Even distribution of state information leading to no single
point of failure [State Complexity]
 Handles voids and sparse networks
• Trade-offs
 Path Stretch
 Probabilistic Reachability
Introduction
Wireless Mesh Networks
Mobile Ad-Hoc Networks
Overlay Networks
10
ORRP Proactive and Reactive Elements
Node B Fwd Table
Node C Fwd Table
Dest Next Hops
A
North
A
A to D
A
1
1.
2.
3.
4.
C
Node F Fwd Table
Dest Next Hops
A
North
120o
F
B
North
Dest Next Hops
North
B
2
Dir
A
F
3
120o
D
D
1
230o
230o
D
North
ORRP Announcements (Proactive) – Generates Rendezvous-to-Destination Routes
ORRP Route Request (RREQ) Packets (Reactive) – Generates Source-to-Rendezvous Rts
ORRP Route Reply (RREP) Packets (Reactive)
Data path after route generation
Introduction
Wireless Mesh Networks
Mobile Ad-Hoc Networks
Overlay Networks
11
Reachability Numerical Analysis
2
1
Probability of
Unreach highest
at perimeters and
corners
P{unreachable} =
P{intersections not in
rectangle}
3 Simulations
NS2
with Intersection
MAM show
4 Possible
Points
around 92%
reachability
57%
98.3%
99.75%
67.7%
Introduction
Wireless Mesh Networks
Mobile Ad-Hoc Networks
Overlay Networks
12
Path Stretch Analysis
Average Stretch for
various topologies
x = 1.255
x = 1.15
•
•
•
•
Square Topology – 1.255
Circular Topology – 1.15
25 X 4 Rectangular – 3.24
Expected Stretch – 1.125
x = 3.24
Introduction
Wireless Mesh Networks
Mobile Ad-Hoc Networks
Overlay Networks
13
State Complexity Analysis/Simulations
GPSR
DSDV
XYLS
ORRP
Node State
O(1)
O(n2)
O(n3/2)
O(n3/2)
Reachability
High
High
100%
High (99%)
Name Resolution
O(n log n)
O(1)
O(1)
O(1)
Invariants
Geography
None
Global Comp.
Local Comp.
ORRP state
scales with
Order N3/2
Introduction
Wireless Mesh Networks
ORRP states are
distributed fairly evenly
in an unstructured
manner
(no single point of failure)
Mobile Ad-Hoc Networks
Overlay Networks
14
ORRP: Simulation Results Summary
• Base Case
 Reach – 99% for Square topologies, 92% for Rectangular topologies (MAM
helped)
 Path Stretch – Roughly 1.2
 Goodput – About 30x more aggregate network goodput than AODV, 10x more
aggregate network goodput than OLSR and 35x more aggregate network
goodput than GPSR with GLS (due to better usage of medium)
• Network Voids
 Average path length fairly constant (Reach and State not different)
• Additional Lines
 Reach/Path Stretch – All showed large gains from 1 to 2 lines but diminishing
returns thereafter
 Goodput – Higher average network throughput with additional lines (better
paths and higher reach) but not by much
• Varying Number of Interfaces
 Significant increase in reachability from 4 to 8 interfaces, but gains trail off
Introduction
Wireless Mesh Networks
Mobile Ad-Hoc Networks
Overlay Networks
15
ORRP: Summary
• ORRP achieves high reachability in random topologies
• ORRP achieves O(N3/2) state maintenance – scalable even
with flat, unstructured routing
• ORRP achieves low path stretch (Tradeoff for connectivity
under relaxed information is very small!)
• ORRP achieves roughly 30X in aggregate network goodput
compared to AODV, 10X the aggregate network goodput
compared to OLSR, and 35X the aggregate network goodput
compared to GPSR with GLS.
Relevant Papers
•
•
•
B. Cheng, M. Yuksel, and S. Kalyanaraman, Rendezvous-based Directional Routing: A Performance Analysis, In Proceedings of IEEE International
Conference on Broadband Communications, Networks, and Systems (BROADNETS), Raleigh, NC, September 2007. (invited paper)
B. Cheng, M. Yuksel, and S. Kalyanaraman, Directional Routing for Wireless Mesh Networks: A Performance Evaluation, Proceedings of IEEE Workshop
on Local and Metropolitan Area Networks (LANMAN), Princeton, NJ, June 2007.
B. Cheng, M. Yuksel, and S. Kalyanaraman, Orthogonal Rendezvous Routing Protocol for Wireless Mesh Networks, Proceedings of IEEE International
Conference on Network Protocols (ICNP), pages 106-115, Santa Barbara, Nov 2006.
Introduction
Wireless Mesh Networks
Mobile Ad-Hoc Networks
Overlay Networks
16
Mobile-ORRP (MORRP) Motivation
ORRP
A
~1.2 vs. SP
Increasing
Mobility
98%
65%
55%
42%
B
Introduction
Wireless Mesh Networks
R
• High reach, O(N3/2) State
complexity, Low path
stretch, high goodput,
unstructured
• BUT.. What happens
with mobility?
• Issues with Mobility
 Interface Handoff
Issue
 Nodes closer
seemingly incur
MORE dynamism
than nodes farther
away
Mobile Ad-Hoc Networks
Overlay Networks
17
MORRP Introduction
What can we do?
A
a
R
B
Introduction
Wireless Mesh Networks
• Replace intersection
point with intersection
region.
• Shift directions of send
based on local movement
information
• Route packets
probabilistically rather
than based on rigid nexthop paths. (No need for
route maintenance!)
• Solution: a NEW kind of
routing table: Directional
Routing Table (DRT)
Mobile Ad-Hoc Networks
Overlay Networks
18
MORRP Basic Example
C
R: Near Field DRT
Region of Influence
B
S
G
R’
A
F
R
Original Path
S
O
Q
N
R
P
S: Near Field DRT
Region of Influence
E
Original
Direction (a1)
Original Path
New
Direction
(a2)
M
D
L
D’
I
H
K
D: Near Field DRT
Region of Influence
J
1. Proactive Element – Generates Rendezvous to Dest Paths
2. Reactive Element – Generates Source to Rendezvous Paths
Introduction
Wireless Mesh Networks
Mobile Ad-Hoc Networks
Overlay Networks
19
The Directional Routing Table
Routing Tables
viewed from Node A
4
Z
3
A
2
D
1
B
Routing Table
C
RT w/ Beam ID
Directional RT (DRT)
Dest
ID
Next
Hop
Dest
ID
Next
Hop
Beam
ID
Dest IDs
(% of Certainty)
Beam
ID
B
C
D
:
Z
B
B
Z
:
Z
B
C
D
:
Z
B
B
Z
:
Z
1
1
3
:
3
B(90%), C(30%)
.
Z(90%), D(40%)
.
1
2
3
4
ID
ID
ID
set of IDs
Set of IDs
set of IDs
• Destination ID % of Certainties for each Beam ID stored within a Decaying
Bloom Filter
• Bloom Filter – A space-efficient probabilistic data structure that is used to
test whether an element is a member of a set.
 Consist of a bit array and a set of k linearly independent hash functions
 Storage: IDs are hashed to each of the k hash functions  stores a ``1’’ in
position in the bit array for each hash function.
 Search: IDs are hashed through each of the k hash functions  if all positions
have a “1”, then the ID is in the set. Otherwise, the ID is not in the set
Introduction
Wireless Mesh Networks
Mobile Ad-Hoc Networks
Overlay Networks
20
DRT: Decaying Bloom Filter Primer
ID: 1
4 Hash h (x) = (x2 + 20) % 32
1
Funcs:
hh11(6)
h(1)
==24
= 24
21
1(2)
ID: 2
h2(x) = x % 32
hh22(6)
h
(1)
==61= 2
2(2)
ID: 6
h3(x) = (x + 5) % 32
hh33(6)
h(1)
==11
6= 7
3(2)
h4(x) = (x3 + 25) % 32
hh44(6)
h(1)
==17
26
=1
4(2)
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31
32 Bit Array: 0 1
0 1
0 0 0 0 1
0 1
0 0 0 0 0 0 0 0 0 0 0 0 0 0 1
0 0 0 1
0 0 1
0 0 0 0 0 0
What policies
Traditional Bloom Filter
For decaying
Search ID 1 – 4 of 4 bits match (IN set)
bits can we
Search ID 6 – 2 of 4 bit match (Not in set) employ?
Decaying Bloom Filter (DBF)
Search ID 1 – 4 of 4 bits match (100% chance in set)
Search ID 6 – 2 of 4 bit match (50% chance in set)
Introduction
Wireless Mesh Networks
DRT
Dest Prob. Beam
ID
(DBF)
7 8
6
5
A
4 3
Mobile Ad-Hoc Networks
1
2
0010..1000
0000..1001
0011..0101
0101..1001
0010..0000
0000..0001
0011..1011
0111..1001
Overlay Networks
1
2
3
4
5
6
7
8
21
DRT Inter-Node Decay
DRT at Node A
S
A
Strong Info
B
Med Info
C
Low Info
D
Noise
0 0 1 0 0 1 0 0 0 0 0
…
1 0 0 0 0 BEAM ID: 1
0 0 0 0 0 1 0 0 0 0 0
…
0 0 1 0 0
BEAM ID: 2
0 1 0 0 1 0 0 0 1 0 0
…
0 0 0 0 1
BEAM ID: 3
0 0 1 0 0 0 1 0 0 0 1
…
0 0 1 0 0
BEAM ID: 4
…
1 0 1 0 1
Merged DBF (Update DBF)
…
1 0 0 0 1
Decayed DBF (50% bits dropped)
B is now 100% sure A is 1 hop
away while only 50% sure C can be
reached through sending out
interface 1
4
3
B
1
A
C
2
Bitwise-OR
0 1 1 0 1 1 1 0 1 0 1
Decay 50% of Bits
0 0 1 0 0 1 0 0 1 0 0
My ID (A)
h1(x), h2(x), …, hn(x)
0 0 1 1 0 1 1 0 1 0 0
Introduction
…
1 0 1 0 1
Wireless Mesh Networks
Broadcasted by A to all Neighbors
Mobile Ad-Hoc Networks
Overlay Networks
22
DRT Intra-node Decay
Time Decay with Mobility
Spread Decay with Mobility
a
q2
7
x
x
q2 > q 1 > q3
q3
q1
8
a
As node moves in direction +x, bits in
DBF of region 8 should decay faster
than of region 7 depending on speed
As node moves in direction +x, bits in DBF of region
2 should be SPREAD to region 1 and 3 faster than
the opposite direction
Beam ID 1
0 1
0 0 0 0 0 0 0 1
0 0 0 0 0 1
0 0 0 0 0 0 0 0 1
0 0 0 0 0 0 0 0 0 0
Beam ID 2
0 0
1 1 0 0 0 0
1 0 0
1 1 0
1 0 0 0
1 0 0 0 0 1 0
1 0 0
1 0 0 0 1 0 0 0 0
1 0
Beam ID 3
0 0 0 0 0 0 1
0 0 0 0 1
0 0 0 0 0 0 0 0 0 1
0 0 0 0 0 0 0 0 0 0 1
0 0
Introduction
Wireless Mesh Networks
Mobile Ad-Hoc Networks
Overlay Networks
23
MORRP Fields of Operation
N
N
N
N
N
N
S
N
R
N
N
N
N
N
N
• Near Field Operation
 Uses “Near Field DRT” to match for
nodes 2-3 hops away
• Far Field Operation
 RREQ/RREP much like ORRP except
nodes along path store info in “FarField DRT”
Introduction
Wireless Mesh Networks
N
N
N
D
N
Mobile Ad-Hoc Networks
N
N
Overlay Networks
24
Performance Evaluation of MORRP
• Metrics Evaluated
 Reachability – Percentage of nodes reachable by each node in network
(Hypothesis: high reachability)
 Delivery Success – Percentage of packets successfully delivered network-wide
 Scalability – The total state control packets flooding the network (Hypothesis:
higher than ORRP but lower than current protocols out there)
 Average Path Length
 End to End Delay (Latency)
 Aggregate Network Goodput
• Scenarios Evaluated




Affect of Time Decay Factor on Reach for various mobility speeds
Affect of Distance Decay Factor on Reach for various mobility speeds
Affect of NF and FF Threshold on Reach for various mobility speeds
Evaluation of metrics vs. AODV (reactive), OLSR (proactive), GPSR with GLS
(position-based), and ORRP under various node velocities, densities,
topology-sizes, transmission rates.
 Evaluation of metrics vs. AODV and OLSR modified to support directional
antennas.
Introduction
Wireless Mesh Networks
Mobile Ad-Hoc Networks
Overlay Networks
25
MORRP: Aggregate Goodput Results
•
•
Aggregate Network Goodput vs.
Traditional Routing Protocols
 MORRP achieves from 10-14X the
goodput of AODV, OLSR, and GPSR
w/ GLS with an omni-directional
antenna
 Gains come from the move toward
directional antennas (more efficient
medium usage)
Aggregate Network Goodput vs. AODV
and OLSR modified with directional
antennas
 MORRP achieves about 15-20%
increase in goodput vs. OLSR with
multiple directional antennas
 Gains come from using directionality
more efficiently
Introduction
Wireless Mesh Networks
Mobile Ad-Hoc Networks
Overlay Networks
26
MORRP: Simulations Summary
• MORRP achieves high reachability (93% in mid-sized, 1300x1300m2
and 87% in large-sized, 2000x2000 m2 topologies) with high mobility
(30m/s).
• With sparser and larger networks, MORRP performs fairly poorly (83%
reach) suggesting additional research into proper DRT tuning is
required.
• In lightly loaded networks, MORRP end-to-end latency is double of
OLSR and about 7x smaller than AODV and 40x less than GPSR w/ GLS
• MORRP scales well by minimizing control packets sent
• MORRP yields over 10-14X the aggregate network throughput
compared to traditional routing protocols with one omnidirectional
interface  gains from using directional interfaces
• MORRP yields over 15-20% the aggregate network goodput compared
to traditional routing protocols modified with 8 directional interfaces
 gains from using directionality constructively
Introduction
Wireless Mesh Networks
Mobile Ad-Hoc Networks
Overlay Networks
27
MORRP: Key Contributions
• The Directional Routing Table
 A replacement for traditional routing tables that routes based on
probabilistic hints
 Gives a basic building block for using directionality to overcome issues
with high mobility in MANET and DTNs
• Using directionality in layer 3 to solve the issues caused by high mobility
in MANETs
• MORRP achieves high reachability (87% - 93%) in high mobility (30m/s)
• MORRP scales well by minimizing control packets sent
• MORRP shows that high reach can be achieved in probabilistic routing
without the need to frequently disseminate node position information.
• MORRP yields high aggregate network goodput with the gains coming not
only from utilizing directional antennas, but utilizing the concept of
directionality itself.
• MORRP is scalable and routes successfully with more relaxed
requirements (No need for coordinate space embedding)
Relevant Papers
•
B. Cheng, M. Yuksel, and S. Kalyanaraman, Using Directionality in Wireless Routing, Under Review in IEEE International Conference on Mobile Ad-hoc and
Sensor Systems (MASS) 2008.
Introduction
Wireless Mesh Networks
Mobile Ad-Hoc Networks
Overlay Networks
28
Wireless Nets: Key Concepts to Abstract
• Directionality CAN be used to provide high reach, high
goodput, low latency routing in wireless mesh (ORRP) and
highly mobile adhoc networks (MORRP)
• Primitives:
 Local directionality is enough to maintain forwarding
along a straight line
 Two sets of orthogonal lines intersect with a high
probability in a bounded region
• Overlay Networks:
 Can we take these concepts to scale unstructured, flat,
overlay networks?
Introduction
Wireless Mesh Networks
Mobile Ad-Hoc Networks
Overlay Networks
29
Virtual Direction Routing Introduction
•
Structured vs. Unstructured Overlay Networks
 Unstructured P2P systems make little or no requirement
on how overlay topologies are established and are easy to
build and robust to churn
•
Typical Search Technique (Unstructured Networks)
Flooding
Normalized
Flooding
 Flooding / Normalized Flooding
• High Reach
• Low path stretch
• Not scalable
 Random Walk
Virtual Direction
Routing
• Need high TTL for high reach
• Long paths
• Scalable, but hard to find rare objects
•
Virtual Direction Routing
 Globally consistent sense of direction (west is always
west)  Scalable interface to neighbor mapping
 Routing can be done similarly to ORRP
•
Random Walk
Focus (for now)
 Small world approximations
Introduction
Wireless Mesh Networks
Mobile Ad-Hoc Networks
Overlay Networks
30
VDR: Neighbor to Virtual Interface Map
Example: Neighbor IDs used
Instead Of SHA-1 Hashes
30 % 8 = 6
15 15 % 8 = 7
30
10 % 8 = 2
8 Virtual Interfaces
26
10
2
10
1
3
0
1
4
68
26
26 % 8 = 2
1
68
5
7
6
15
30
68 % 8 = 4
• Neighbors are either physical neighbors connected by interfaces or
neighbors under a certain RTT latency away (logical neighbors)
• Neighbor to Virtual Interface Mapping
 Each neighbor ID is hashed to 160 bit IDs using SHA-1 (to standardize small or
large IDs)
 The virtual interface assigned to the neighbor is a function of its hashed ID
(Hashed ID % number of virtual interfaces)
Introduction
Wireless Mesh Networks
Mobile Ad-Hoc Networks
Overlay Networks
31
VDR: State Seeding and Route Request
State Seeding –
|10 – 1| = 9
|26 – 1| = 25
10
26
State info forwarded
in orthogonal
2 1
directions, biasing
3
0
packets toward IDs
1
that are closer to
4
7
68
SOURCE ID. Packets
5 6
are forwarded in
virtual straight lines.
30
Ex: Seed Source: Node 1
Route Request –
RREQ packets are
forwarded in
orthogonal
directions, biasing
packets towards
REQUESTED ID
26
1
3
0
1
4
68
5
2
67
48
3
10
4
28
15
5
|5 – 1| = 4
5
|13 – 1| = 12
30
2
7
4
28
|5 – 12| = 7 5
|13 – 12| = 1
5
1
0
5
5
7
6
|14 – 1| = 13
|22 – 1| = 21
14
2
0
3
7
4
6
13
Mobile Ad-Hoc Networks
55
22
10
1
10
4
Wireless Mesh Networks
3
6
3
15
0
1
7
6
2
13
67
48
10
1
|10 – 12| = 2
|26 – 12| = 15
2
Ex: Route Request: Node 12
RREQ Source: Node 1
Introduction
10
1
1
0
13
5
|6 – 12| = 6
|38 – 12| = 26
7
6
38
6
Overlay Networks
32
VDR: Simulation Parameters
46
68
RREQ Path
30
1
5
10
13
26
48
Flooding
RREP Path
Rendezvous Node
6
38
2
RREQ: Node 12
Seed Path
VDR Route Request
Virtual View
•
12
Simulation of VDR vs. RWR, VDR-R
PeerSim – 50,000 Nodes, Static + Dynamic Network
 Reach Probability – High (98% w/ TTL of 100)
 Average Path Stretch – High (16)
 State and Load Spread – Not evenly distributed
Introduction
Wireless Mesh Networks
Virtual Direction
Routing
VDR – Random NB
Send (VDR-R)
 VDR-R: VDR with random neighbor forwarding (no biasing)
 RWR: Data is seeded in 4 random walks and 4 walkers are sent
for search
•
Normalized
Flooding
Random Walk
Routing (RWR)
Random Walk
Mobile Ad-Hoc Networks
Overlay Networks
33
VDR: Robustness Results
• State Distribution Network-wide
 Average States maintained
relatively equal for VDR, VDR-R
and RWR at 350-390
 VDR States are not very evenly
distributed, with some nodes
having more state than others.
This is due to the sending bias
• Robustness to Network Churn
 VDR drops only 5% compared to
VDR-R and RWR which drop 1215% reach when going from 0% to
50% network churn
 Even with a TTL of 50, VDR reaches
a good amount of the network
Introduction
Wireless Mesh Networks
5% drop
15% drop
12% drop
Mobile Ad-Hoc Networks
Overlay Networks
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VDR: Key Contributions
• Introduction of the concept of Virtual Directions to eliminate
need for structure (coordinate space, DHT structures) to scale
flat, unstructured overlay networks
• A flat, highly scalable, and resilient to churn routing algorithm
for overlay networks
• VDR provides high reach (98% even only for a TTL of 100 in a
50,000 node network)
• VDR drops only 2-5% going from 0% churn to 50% churn
Relevant Papers
•
B. Cheng, M. Yuksel, and S. Kalyanaraman, Virtual Direction Routing for Overlay Networks, In preparation for submission to IEEE Peer to Peer
Computing (P2P) 2008.
Introduction
Wireless Mesh Networks
Mobile Ad-Hoc Networks
Overlay Networks
35
Conclusion / Future Work
• Used Directionality to scale wireless networks (ORRP, MORRP)
• Used concept of Virtual Directions to scale overlay networks
(VDR)
• Future Work: Extensions
 Virtual direction abstraction analysis
 Hybrid ORRP (that works with omnidirectional and directional
antennas)
 Analysis of Effect of knobs in MORRP
• New Directions with Directionality
 Multi-path / multi-interface diversity
 Directional Network Coding
 Destination-based routing based on local directions
Introduction
Wireless Mesh Networks
Mobile Ad-Hoc Networks
Overlay Networks
36
Thank You!
• Questions and Comments?
• Papers / Posters / Slides / Code
[ http://networks.ecse.rpi.edu/~bownan ]
• [email protected]
Introduction
Wireless Mesh Networks
Mobile Ad-Hoc Networks
Overlay Networks
37