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H AZY S IGHTED L INK S TATE R OUTING P ROTOCOL

H AZY S IGHTED L INK S TATE R OUTING P ROTOCOL. Eleonora Borgia. Pervasive Computing & Networking Lab. PerLab IIT – CNR eleonora.borgia@iit.cnr.it. MobileMAN Project - Helsinki – June 7/8, 2004. Main Target. I dentify a routing protocol suitable for a c ross-layer architecture :

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H AZY S IGHTED L INK S TATE R OUTING P ROTOCOL

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  1. HAZY SIGHTED LINK STATE ROUTING PROTOCOL Eleonora Borgia Pervasive Computing & Networking Lab. PerLab IIT – CNR eleonora.borgia@iit.cnr.it MobileMAN Project - Helsinki – June 7/8, 2004

  2. Main Target • Identify a routing protocol suitable for a cross-layer architecture: • in term of scalability, performance and efficiency; • providing more advantages to the other protocols. reactive protocols are more efficient than proactive ones for the introduced overhead • MANET standpoint: • OUR standpoint: • The protocol overhead cannot be computed in isolation; • New cross-layer metrics must be applied to compute it; • It’s useful having a knowledge (at least partial) of the network topology, also to provide it to other protocol layers. proactive protocols are more suitable

  3. Overview of Link State Routing • In literature there are different approaches aimed to reduce the overhead introduced by protocols based on LS: • Efficient Dissemination : updates sent throughout the network more efficiently (e.g. OLSR, TBRF, STAR) • Limited Dissemination : restriction of the scope of routing updatesin space and time (e.g. hierarchicallyLS, FSR, GSR, HSLS)

  4. Total overhead(1) • TRADITIONALLY: • OVERHEAD  CONTROL OVERHEAD • Amount of bandwidth require to construct and maintain routes • PROACTIVE OVERHEAD: number of packets exchanged between nodes in order to maintain node’s routing table • REACTIVE OVERHEAD : consumed bandwidth for Request/Reply messages • As N increases, keeping route optimality is much expensive particularly in LS; • SUB-OPTIMAL paths may be used. The impact of SUB-OPTIMAL routes and its overhead must be taken into account.

  5. Total overhead(2) A S D B NEW DEFINITION* : TOTAL OVERHEADof protocol Xis the sum of: PROACTIVE OVERHEAD; REACTIVE OVERHEAD; SUB-OPTIMAL OVERHEAD: Difference between the bandwidth consumed using the sub-optimal paths and that eventually consumed if the data had followed the shortest available path(s). Ex: A = 3 hopsB = k hops SUB-OPT ov= (k-3)*Packet_length (*) C. Santivanez, I. Stavrakakis et al, “On the scalability of Ad Hoc Routing Protocols”, INFOCOM 2002

  6. Hazy Sighted Link State (HSLS)(1) • Proactive protocol with Limited Dissemination; • Scope’s restriction: LSU packetsare broadcasted periodically over the networkwith frequenciesfithatdecreaseswith the distance from the node itself; • Each node has a partial knowledge of the network (i.e. not real-time uploaded): • detailed view of 1-hop neighborhood; • “hazy” knowledge of distant nodes. • HSLS is based on the observation that nodes that are far away not need to have a complete topological information in order to make a good next hop decision

  7. Hazy Sighted Link State(HSLS)(2) • te:: period with which a LSU is sent through the network • TTL = 2i • A node wakes up every tesec and sends a LSU with TTL=2 if there has been a link status change in the last tesec; • Every 2i-1 * tesec (with i=1,2,3..) a node wakes up and sends a LSU with TTL= 2iif there has been a link status change in the last 2i-1 * tesec; • Every tbsec (tb>te) a global LSU (TTL=) is sent in the entire network to give a complete overview of the network topology, even if there’s no link changes. High mobility scenario:

  8. HSLS Example LSU packet LSU packet LSU packet Originator ID Originator ID Originator ID TTL =  TTL = 4 TTL = 2 Neighbor ID 1 Neighbor ID 1 Neighbor ID 1 G G G G Neighbor ID 2 Neighbor ID 2 Neighbor ID 2 A B U U U T = te : F F F F T = 4 te : T = 2 te : T T T A A A B B B H H H H E V V V C N N N N LSU packet LSU packet W W LSU packet LSU packet S E E E Originator ID C C C D O O O O X X X R R R TTL M M M M D D D Neighbor ID 1 J J J J Z Z Neighbor ID 2 L L L L P P P Q Q Q K K K K Broadcast transmission Network size: 5 hops

  9. Comparative study* (*) C. Santivanez, I. Stavrakakis et al, “On the scalability of Ad Hoc Routing Protocols”, INFOCOM 2002

  10. MobileMAN project Ad Hoc Framework (HUT) • HSLS software architecture design HSLS Subsystem Proactive Subsystem Hybrid Subsystem Reactive Subsystem Common Modules • Possible integrationwith HUTAd Hoc framework • Interface with the cross-layer architecture and cooperation with other protocol layers • Test and Performance evaluation

  11. Software Architecture Initialization Garbage Collector NEST Communication HSLS Packet Mangement Hello LSU Socket Management Processing

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