Ad-hoc Networking with AODV by Ashok Panwar

1. Presented By:-
Ashok Panwar
Technical Officer in ECIL(NPCIL)
Tarapur, Mumbai
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2. Outline of Presentation
 Ad Hoc Networks in general
 AODV in particular
 Recent results from MANET
 Internet Gateways for ad hoc networks
 Address auto configuration
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Ashok Panwar
Technical Officer in ECIL

3. Ad Hoc Network characteristics
 peer-to-peer
 Multi hop
 dynamic
 zero-administration
 low power
 autonomous
 Auto configured
But, most of these have exceptions!
Idea: let (?almost?) every node be a router
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Ashok Panwar
Technical Officer in ECIL

4. Commercial (or not!) Opportunities
 Conferencing
 Home networking
 Range extension for cellular base stations
 Emergency services
◦ Ambulance
◦ Police
 Hospitals
 Embedded computing applications
◦ Ubiquitous computers with short-range interactions
◦ Automotive/PC interaction
 Enable computing where subnets do not exist
 Jungle telemetry
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Ashok Panwar
Technical Officer in ECIL

5. Technical/Market/Political hurdles
 Scalability (memory search time, bandwidth, processing)
 Power budget vs. latency
 Protocol deployment, incompatible standards
 Why should one node “waste power'' to help a neighbor ?
 Wireless data rates
 Obsoletes the client/server model...  breaks a lot of
protocols
 User education, acculturation
 Antenna inconvenience (not anymore, really)
 Higher bit-error-rate (BER)
 Additional security exposure
 Non-ubiquitous coverage
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Ashok Panwar
Technical Officer in ECIL

6. On-Demand Routing Protocols
 Eliminate route table updates for routes that are not used
 Fewer control packets:
◦  better scalability, reduced congestion, better robustness
◦  reduced processing requirement
 Even more localization for topology changes if distance
vector
 Also can be made to work for (partial) link state
◦ or, better, hybridized distance vector and link state
 Downsides:
◦ Latency
◦ Route Discovery broadcasts
◦ ICMP Unreachable only after Route Discovery attempt
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Ashok Panwar
Technical Officer in ECIL

7. Mobile Ad Hoc Networking (MANET) / AODV
 AODV: on-demand, and distance vector
◦ Route caching & timeout offers improvement over others
◦ Proved “correct”
◦ Interoperability testing, and (soon?!) Experimental RFC status
 AODV uses network-wide RREQ, unicast RREP along
reverse path to source of the request.
 DSR uses similar route discovery, maintains source routes
 OLSR and TBRPF are link state, proactive protocols
 Active discussion about Internet Gateways
 Address Auto configuration
 Reducing retransmissions for system-wide flooding
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Ashok Panwar
Technical Officer in ECIL

8. AODV Features
 Reactive routing protocol; route discovery cycle for
route finding
 Route repairs and TTL restrictions reduce network-
wide flooding
 Maintenance of active routes
 Loop freedom achieved through sequence numbers
 No overhead on data packets
 Scalability shown to 10,000 nodes
◦ performance suffers
 Integrated multicast protocol (MAODV) specified
◦ multiple next hops
◦ group leader maintains sequence number
 QoS extension specified (undergoing revision)
 AODV for IPv6 is specified, built, and works
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Ashok Panwar
Technical Officer in ECIL

9. AODV Unicast Route Discovery Initiation
Route Request (RREQ) broadcast flood
Source
Destination
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Ashok Panwar
Technical Officer in ECIL

10. AODV Unicast Route Discovery Completion
Route Reply (RREP) propagation
Destination
Source
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Ashok Panwar
Technical Officer in ECIL

11. Internet Gateways for Ad Hoc Networks
 Our model: do not inject per-host routes into Internet
 Good start: ad hoc nodes use gateway as default router
◦ but it could be multiple hops away
◦ plus, the ad hoc nodes need to know its IP address
◦ router solicitation/advertisement “work”, with changes
 Gateway should be “protocol-agnostic” (for any MANET
protocol)
 Gateway needs a host route for each MANET node
Gateway
Entry node
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Ashok Panwar
Technical Officer in ECIL

12. Address Auto configuration
 Node discovers Internet-routable prefix from Internet Gateway, if any
 Otherwise, use canonical site-local address
 Required: some variety of Duplicate Address Detection (DAD)
 For connected networks, RREQ/RREP does the job
◦ tricky part: what is the source address?
◦ have specified AREQ and AREP for “general” case (should work with protocols other
than AODV)
 The hard part: dealing with network merge or healing
Gateway
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Ashok Panwar
Technical Officer in ECIL

13. Ad Hoc Networking Research
 MobiHoc (ACM SIGMOBILE) (plus quite a few others!)
◦ Third conference held in June – 150 papers submitted
 Active research areas (a few among many!)
◦ Inherent capacity bounds?
◦ Better Routing
◦ Automotive (“parallel” one-dimensional networks?)
◦ Backbones, Clustering
◦ Power control
◦ Simulations seem quite untrusted
 AODVng
◦ Gray zones (interference range vs. signal range; HELLO nonworking)
◦ QoS/Diffserv/”no free lunch”
◦ Security (!!)
◦ Implementer’s mailing list
◦ Multipath
◦ AODVjr.
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Ashok Panwar
Technical Officer in ECIL

14. Summary and Conclusions
 Ad Hoc Networking is well-established as a viable
research area
 Infrastructureless operation has many applications
 On-demand protocols offer many advantages
 AODV makes use of advantages from both Distance-
Vector and On-demand
 AODV has good chances for standardization
 Ad hoc networks can be glued to the Internet and then
provide wireless extension domains
 Address autoconfiguration techniques have been
adapted
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Ashok Panwar
Technical Officer in ECIL

15. Various Ad Hoc Routing Projects
 DSR (Dave Johnson, CMU)
 WINGs (JJ Garcia/UCSC)
 ROAM (JJ Garcia/UCSC)
 WAMIS (Gerla/UCLA)
 ODMRP (Gerla et.al/UCLA)
 TRAVLR (Kleinrock/UCLA)
 Tora/IMEP (Park, Corson/UMD)
 Link Quality (Rohit Dube/UMD)
 LAR (Texas A&M)
 TBRPF (SRI)
 OLSR (Inria: Clausen./Jacquet)
 DSDV (Dest. Sequence #'s)
 AODV (refinement of DSDV)
 AOMDV (Multipath – Das/Marina)
 Hierarchical (Akyildiz/Georgia Tech)
 GPSR (Karp/Harvard)
 CBRP (Singapore)
 Terminodes (EPFL)
 MMWN (Steenstrup/BBN)
 ABR (C.K. Toh)
 STAR (JJ Garcia/UCSC)
 ZRP (Zygmunt Haas/Cornell)
 Fisheye/Hierarchical (UCLA)
 CEDAR (Urbana-Champaign)
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Ashok Panwar
Technical Officer in ECIL

16. Any Questions???
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