DYMO: Dynamic MANET On-Demand DYMO: Dynamic MANET On-Demand IETF Draft submitted by MANET WG Work in progress Descendant of DSR and AODV A rewrite of AODV, using different terminology and packet format, but having the same basic functionality Table driven routing • Significantly smaller amount of routing information than DSR Path accumulation (cf. DSR) is optional No precursor list in routing table entries Makes use of the generalized MANET packet format Extensible through TLVs Basic Internet connectivity AODV and DSR are not consider Internet access DYMO maintains routing tables with gateway and prefix information DYMOcast Packet transmission to all MANET routers within reception range Broadcast in IPv4 or all node multicast in IPv6 Maintaining Local Connectivity may use any mechanisms Link layer feedback • difficulty of obtaining IEEE 802.11 feedback in real networks Hello messages • periodic one-hop L3 message • many ad hoc networks utilize hello messages • depends on many factors such as loss settings, message size, rate, ... Neighbor discovery • relay highly on broadcast/multicast capabilities of the underlying link layer • need optimization Route timeout • difficulty of determining the proper timeout because of dynamic mobility 1
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DYMO: Dynamic MANET On-Demand IETF Draft submitted by MANET WG Work in progress Descendant of DSR and AODV A rewrite of AODV, using different terminology.
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demand routing protocol which use a link reversal algorithm
Provides loop-free multi-path routes to a destination node
Route establishment function is performed only when a source does not have any directed link Query/Update Height of node from the
destination
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TORA Route MaintenanceTORA Route Maintenance
When a partition is detected, all nodes in the partition are informed, and link reversals in that partition cease
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LAR: Location-Aided Routing [7-LAR: Location-Aided Routing [7-13]13] Utilizes the location
information (form GPS) to reduce the control packets overhead Flooding is restricted to a
small RequestZone
LAR1 algorithm
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LAR2 algorithm RREQ packet includes the
distance S between source and destination
When an intermediate node i receives RREQ, computed the distance DISTi to the destination
• If DISTi < S + δ, forward RREQ• Otherwise, discard
DREAM : Distance Routing Effect DREAM : Distance Routing Effect Algorithm for MobilityAlgorithm for Mobility
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ABR: Associativity-Based Routing ABR: Associativity-Based Routing [7-14][7-14] A beacon-based on-demand
routing protocol Selects routes based on the
stability of the wireless link Only links that have been
stable for some minimum duration are utilized
motivation: If a link has been stable beyond some minimum threshold, it is likely to be stable for a longer interval. If it has not been stable longer than the threshold, then it may soon break (could be a transient link)
Association stability determined for each link measures duration for which
the link has been stable Prefer paths with high
aggregate association stability
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SSA: Signal Stability Based SSA: Signal Stability Based Adaptive Routing [7-15]Adaptive Routing [7-15]Similar to DSRSignal strength is measure for determining
signal stabilityStrong/stable linkWeak/unstable link
A node X re-broadcasts a Route Request received from Y only if the (X,Y) link is deemed to have a strong signal stability
Signal stability is evaluated as a moving average of the signal strength of packets received on the link in recent past
An alternative approach would be to assign a cost as a function of signal stability
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Hybrid Routing ProtocolsHybrid Routing Protocols
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ZRP: Zone Routing Protocol [7-18]ZRP: Zone Routing Protocol [7-18] Routing zone of a given node: a subset of the
network, within which all nodes are reachable within less than or equal to zone radius hops
Source S checks whether destination D is within its zone Source
• If D is within S’s zone, deliver the packet directly• Otherwise, bordercast the RREQ to its peripheral nodes
Peripheral nodes• If any peripheral node finds D to be its routing zone,
it sends RREP back to S• Otherwise, re-bordercast RREQ
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ZHLS: Zone-Based Hierachical Link ZHLS: Zone-Based Hierachical Link State Routing Protocol [7-19]State Routing Protocol [7-19] A hybrid routing protocol
Intra-zone routing:• Proactive routing• link state algorithm (SPF)
A hierarchical routing protocol Reactive routing Forms non-overlapping zones, using
the geographical location information of the nodes
Minimal energy consumption per packetMaximize network connectivityMinimum variance in node power levels
Distribute the load among all bodes
Minimum cost per packetRemaining battery charge cost factor for
routing
Minimize maximum node costMinimize the max cost per node for a packet
after routing a number of packets or after a specific period
This delays the failure of a node19
Power-Aware RoutingPower-Aware Routing [Singh98Mobicom,Chang00Infocom] Define optimization criteria as a function of energy
consumption. Examples: Minimize energy consumed per packet Minimize time to network partition due to energy depletion Maximize duration before a node fails due to energy depletion
Assign a weigh to each link Weight of a link may be a function of energy consumed
when transmitting a packet on that link, as well as the residual energy level low residual energy level may correspond to a high cost
Prefer a route with the smallest aggregate weight Possible modification to DSR to make it power aware (for
simplicity, assume no route caching): Route Requests aggregate the weights of all traversed links Destination responds with a Route Reply to a Route Request if
• it is the first RREQ with a given (“current”) sequence number, or• its weight is smaller than all other RREQs received with the current