To Geeks...

1
From Greeks...
To Geeks...
2
MOBILE AD HOC NETWORKS APPLICATIONS AND ROUTING
PROTOCOLS
Presented By Geek
Gaurav Dawra
3
(No Transcript)
4
Ad Hoc Networks - An Insight
Pictures from www.cise.ufl.edu
5
Example Pictures Thousand words.
From www.cise.ufl.edu
6
(No Transcript)
7
(No Transcript)
8
(No Transcript)
9
(No Transcript)
10
Packet Hop
Connectivity that Moves You!!
11
Motivation

• Colleagues attending a conference wants to share
  information
• Without subscribing to a wireless service
  provider.
• People searching for missing child want to share
  location and
• other information.
• Teams of first responders from different
  agencies want to share
• plan of action.
• Children want to play a network game wirelessly.
  
• And many more..

12
Broadband Connectivity Anytime, Anywhere ..

• Instant Mobile Mesh Network with Peer-to-Peer
  Connectivity

13
Solving Problems
Packet hop addressed the complete set of mobile
mesh Networking Solutions
14

• Routing
• Mobile Mesh Routing Protocol has to adapt
  quickly
• to changing topology
• Each node maintains routing table
• Packets are forwarded based on number of hops,
  network
• congestion and link bandwidth.

15
Deployment
PacketHop deploys the first multi-agency,
mission-critical, mobile broadband
communications network for the homeland security
market
Pictures from Packet Hop Website
16
Topology Broadcast Based on Reverse-Path
Forwarding (TBRPF)
Overview of TBRPF

• Neighbor discovery
• Uses differential HELLOs, which include only the
  IDs of new neighbors and recently lost
  neighbors(Unlike OSPF which includes ID of all
  nodes).
• TBRPF Node Discovery (TND) completely modular,
  and performs only the discovery of new neighbors
  and the loss of old neighbors.
• Routing (including topology discovery) Each
  node reports only a portion of its source tree,
  called its reportable subtree (RT), to all
  neighbors
• using periodic updates (e.g., every 5 or 6 s)
• uses differential updates (e.g., every 1 or 2 s),
  which allow important updates to propagate
  quickly in small messages to all nodes affected
  by the update .
• without using sequence numbers for updates .

17
Overview of TBRPF (continue)
Each Node Maintaines a Neighbor Table for each
interface I---J
I--------------J
Neighbor Reply Neighbor Request Neighbor
Lost Maintains Special Count
LINK
1-Way 2-Way LOST
18
Changes from version 03 to version 05

• Introduction of support for multiple interfaces,
  associated hosts, and network prefixes.
• Introduction of support for link metrics.
• Option to report full source tree to provide
  increased robustness if sufficient bandwidth is
  available.

19
TBRPF Neighbor Discovery

• Uses differential HELLOs, which report only
  neighbors whose state has recently changed
  (unlike OSPF). This reduces overhead and allows
  HELLOs to be sent more frequently.
• All neighbors are reported periodically in
  topology updates (not part of neighbor discovery)
  less frequently.

20
Overview of TBRPF Routing module

• Each node i reports, in periodic(5sec) and
  differential updates(1-2 sec), its reportable
  subtree RT Links(U,V) of T is in RT such
  that u is in
• Reported Node Set (RN) , which is computed as
  follows
• Node I includes a neighbor J in RN iff the node
  I determines that one of its neighbors may select
  I to be its next hop on its shortest path to J.
• ---To accomplish this, each node computes the
  min-hop(upto 2 hops) paths from each neighbor to
  each other neighbor.
• ---As a result, each node reports only a
  relatively small part of its source tree.
  Each node computes its source tree T using
  a variation of Dijkstra
• TBRPF Do not Use sequence numbers for updates
  thus avoiding overhead
• Another approach--- A link (u,v) is in Topology
  Graph,TG (includes nodes that are UP) only if it
  is reported by the next hop p(u) on the shortest
  path to node u. Computes T as the shortest path
  tree within TG

21
Example of reportable subtrees
Node 2 selects itself as a parent for all
neighbors.
9
6
7
8
5
4
2
3
1
13
As a result, node 2 reports its entire source
tree, while nodes 6 and 10 report only a small
part of their trees.
12
10
11
15
14
Node 2s reportable subtree
Node 6s reportable subtree
Node 10s reportable subtree
22
Using link metrics

• Nodes may optionally include link metrics in
  Topology Update messages, and compute shortest
  paths w.r.t these metrics. (The proposed size of
  a metric is 8 bits.)
• Possible metrics can be based on signal strength,
  stability, reliability, bandwidth, power, delay,
  HELLO counts, etc.

.9
.9
.9
.9
.9
u
i
1.0
1.0
1.0
1.0
23
Multihop delay performance using ping tool
24
Simulation comparison of TBRPF and AODV50
nodes, 20 sources, 670x670 area, no mobility
DELAY
PERCENT DELIVERED
congested
25
Roof Net Hardware Software (NODE)

• Hyper link Technologies 8DBi Omni directional
  antenna on roof top.
• 50 m from antenna Cable Connects to lightning
  arrestor and
• then to 802.11 card.
• Use Linux HostAP 802.11 driver , not enabling
  software access point.
• Node are Wireless Router Appliances
• (Roofnet Source bundled with CLICK)

Communicating Packet Queuing packet
scheduling Modification
26
More on Node Software

• Redhat 9.0 2.4.20 kernel version
• Click eases routing by allowing upgrads without
  reboot of system
• Upgrade of software are easily done over the
  roofnet

Computer /ISP
Antenna
27
Routing Protocol

• Actually designed for static nodes
• Use SrcRR( new routing protocol) inspired by DSR
• Local Link State database

N0
Nd

• SrcRR uses ETX metric to help it choose good
  routes, it means
• loss rates in both directions.

28
How quality of route is determined?

• Updates ETX metric every time from preceding
  node.
• 802.11 card indicates if around 10 packets are
  lost ( link broken)
• Route is asymmetric or broken ( One way)
• Link quality averages over tens of seconds
• Source node sees new metric for link,
  recalculates metric?
• (Overhead but required)
• Discovers new route having better ETX metric, it
  will flood
• a new query? (Imagine in case of mobile
  nodes!!?)
• Why NAT is used??
• Roofnet uses internal IP addresses 10.x.x.x for
  management and
• for SrcRR routing.

29
Why NAT..
Each Node runs NAT thats makes packet connected
to Ethernet Appear to be coming from roofnets
node 10.x.x.x
30
Time to Compare!!...

• Designed for mobile nodes
• TBRPF based on OSPF(open
• Shortest path first)
• Maintains Neighbor table and
• Routing Table
• Also used modified dijkstra algo
• Uses TND protocol to discover the
• Neighbor nodes
• Avoids overhead by NOT using seq
• no. for topology updates.
• It might use ETX metric for
• Topology update
• And many more

• Designed for static nodes
• SrcRR based on DSR routing
• Algorithm
• Maintains routing table
• Max. hops used are 4
• Used dijkstra algo to find
• Source route by applying
• algorithm to the link state
• database of metrics.
• Protocol does put lot of over-
• -head while establishing routes.
• Routes are selected based on
• ETX metric , ETX measures
• loss rates in both directions.

31
From www.cise.ufl.edu
32
References
Books on MANET Charles Perkins Ad Hoc
Networking, Addison Wesley IETF MANET working
group http//www.ietf.org/html.charters/manet-c
harter.html W. Kellerer et al., (Auto) Mobile
Communication in a Heterogeneous and
Converged World, IEEE Personal
Communications, December 2001.
www.packethop.com http//citeseer.nj.nec.com/che
n01ad.html Internet draft for
TBRPF http//www.erg.sri.com/projects/tbrpf/docs/d
raft-ietf-manet-tbrpf-11.txt Proof of
Correctness for TBRF http//www.erg.sri.com/projec
ts/tbrpf/docs/tbrpf_proof.txt Autonomous teams
for unmanned aerial vehicles http//www.erg.sri.co
m/publications/429-PA-01-120_ieee.pdf
33
Thank You!!