H AZY S IGHTED L INK S TATE R OUTING P ROTOCOL Eleonora Borgia Pervasive Computing & Networking Lab. PerLab IIT – CNR MobileMAN Project - Helsinki – June 7/8, 2004

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.  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. reactive protocols are more efficient than proactive ones for the introduced overhead proactive protocols are more suitable

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 updates in space and time (e.g. hierarchically LS, FSR, GSR, HSLS)

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 Total overhead (1) The impact of SUB-OPTIMAL routes and its overhead must be taken into account. As N increases, keeping route optimality is much expensive particularly in LS; SUB-OPTIMAL paths may be used.

Ex: A = 3 hops B = k hops SUB-OPT ov = (k-3)*Packet_length Total overhead (2) NEW DEFINITION * : TOTAL OVERHEAD of protocol X is the sum of: 1.PROACTIVE OVERHEAD; 2.REACTIVE OVERHEAD; 3.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). SD A B (*) C. Santivanez, I. Stavrakakis et al, “On the scalability of Ad Hoc Routing Protocols”, INFOCOM 2002

Proactive protocol with Limited Dissemination ; Scope’s restriction: LSU packets are broadcasted periodically over the network with frequencies f i that decreases with 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 Hazy Sighted Link State (HSLS) (1)

Hazy Sighted Link State (HSLS) (2) 1.A node wakes up every t e sec and sends a LSU with TTL=2 if there has been a link status change in the last t e sec; 2.Every 2 i-1 * t e sec (with i=1,2,3..) a node wakes up and sends a LSU with TTL= 2 i if there has been a link status change in the last 2 i-1 * t e sec; 3.Every t b sec (t b >t e ) 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. t e: : period with which a LSU is sent through the network TTL = 2 i High mobility scenario:

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

Comparative study * Routing ProtocolTotal_overhead SLS (proactive) (N2)(N2) DSR (reactive)  ( N 2 +N 2 *log 2 N ) ZRP (hybrid) (N2)(N2) HSLS  ( N 1.5 ) (*) C. Santivanez, I. Stavrakakis et al, “On the scalability of Ad Hoc Routing Protocols”, INFOCOM 2002

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

Software Architecture HSLS Initialization Garbage Collector N E S T Communication Packet Mangement Socket Management Processing LSU Hello