1. 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

2. 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?

3. Hierarchical Routing
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/H
Proposed hierarchical schemes include:
Hierarchical State Routing (HSR)
Fisheye State Routing (FSR)
Landmark Routing
Zone routing (hybrid scheme)

4. 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

5. HSR - physical multilevel partitions5 1 7 6 11 4 2 3 10 9 8
Level = 1
Level = 2
HSR table at node 5:
DestID 1 6 7
<1-2->
<1-4->
<1-3>
Path
5-1
5-1-6
5-7
HID(5): <1-1-5>
HID(6): <3-2-6>
Hierarchical addresses
(MAC addresses)

6. 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

7. 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

8. Fisheye State Routing (FSR)1 2 3 4 5 6 7 8 9 10 11 12 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 34 35 36
Hop=1
Hop=2
Hop>2 13 1 2 3 4 5 6 7 8 9 10 11 12 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 34 35 36
Hop=1
Hop=2
Hop>2 13 1 2 3 4 5 6 7 8 9 10 11 12 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 34 35 36
Hop=1
Hop=2
Hop>2 13
Scope of Fisheye

9. 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

10. Message Reduction in FSR TC (Topology Control) message
LST
HOP
0:{1}
1:{0,2,3}
2:{5,1,4}
3:{1,4}
4:{5,2,3}
5:{2,4} 1 2
LST
HOP
0:{1}
1:{0,2,3}
2:{5,1,4}
3:{1,4}
4:{5,2,3}
5:{2,4} 2 1 1 3 2
LST
HOP
0:{1}
1:{0,2,3}
2:{5,1,4}
3:{1,4}
4:{5,2,3}
5:{2,4} 3 2 1 4 5

11. 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)

12. Scalability Property of OFLSR
Scalability to Node Mobility
100 nodes, 1600mX1600m field, 367m Tx range
IEEE 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
Data Packet Delivery Ratio
Node mobility speed (m/s)
Data Packet Delivery Ratio

13. Scalability Property of OFLSR
Scalability to Node Mobility
Total # of TC relayed
Total # of TC received

14. Scalability Property of OFLSR
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
Data Packet Delivery Ratio
Network Size (# of nodes)
Delivery rate vs Network Size

15. Scalability Property of OFLSR
Scalability to Network Size
Total # of TC relayed
Total # of TC received

16. 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

17. 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

18. 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 Subnet
Landmark

19. 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 Subnet
Landmark

20. 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
Logical Subnet
Landmark

21. Landmark Routing In action
LM2
LM1
LM3
Logical Subnet
dest
source
local routing
Long haul routing
Node address = {subnet ID, Host ID}
Look up local routing table to locate dest  fail
Look up landmark table to find destination subnet  LM1
Send a packet toward LM1

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

23. 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)
H (Routing overhead)
Total O/H
N: total # of nodes; d: avg # of one-hop neighbors (degree);
G - avg # of nodes in one group; m – avg # of nodes in one scope
h: scope size in hops; H: routing overhead in Bytes
The efficiency of lm operation largely depends on the scoped routing operation. Now let’s take a look at scope configuration.
The Q is:
The calculation here is based on an assumption that a group resides exactly into one scope. So the # of group members is same as # of nodes in a scope.
We give routing overhead as a function of scope size in hop distances.
This is how oh of landmark routing part relates to hop distance. When scope hop distance increase, groups size increases. The # of landmark table enties decrease. The oh decreases.
For local routing o/h, when scope becomes large, more nodes presented in local routing table, so oh increase with the scope size.
then, obviously the total overhead has a minimum value.
Local route O/H
Landmark O/H
h (scope size)

24. LANMAR enhances MANET routing schemes
We compare:
MANET routing schemes: DSDV, OLSR and FSR; and
(b) same MANET schemes, BUT with LANMAR overlay on top

25. Delivery Ratio
OLSR
DSDV
FSR
LANMAR-DSDV
LANMAR-OLSR
LANMAR-FSR
DSDV and FSR decrease quickly when number of nodes increases
OLSR generates excessive control packets, cannot exceed 400 nodes

26. 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

27. Fast BB links are “advertised” and immediately used
UAV
Backbone Node
Landmark
Logical Subnet
source
dest.
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

28. Backbone Node Automatic Deployment
Objectives
Robust and autonomous backbone network maintenance
Uniform distribution to cover the field
Approach
Dynamic backbone node election: Deploy redundant backbone capable nodes and select a few
Backbone node automatic placement: Relocate backbone nodes from dense to sparse regions

29. 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)

30. Backbone Node Deployment
Deployment algorithm
Assumption: Backbone nodes know their position (from GPS)
Each BN broadcasts its position periodically via scoped flooding.
Let the distance between x and y = Dxy. We define the repulsive force between them where A is a constant.
Vector sum of repulsive forces from neighbors determines direction and speed of motion

32. 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)

33. 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

34. Variable number of Backbone Nodes
Decrease of average end-to-end delay while increasing # of backbone nodes

35. Variable number of Backbone Nodes
Increase of delivery fraction while increasing # of backbone nodes

36. Variable Speed with 1000 nodes
Delivery fraction while increasing mobility speed

37. 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
48 bits
16 bits
64 bits
GroupID
Node ID
Network ID
Subnet
Mask
0000 … 000
11…11 …
IPv6: