Download presentation
Presentation is loading. Please wait.
Published bySteven Hunt Modified over 9 years ago
1
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 routi ng 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
2
DYMO – Route Discovery Similar to the route discovery of the AODV DYMO uses only RE although AODV and DSR use RREQ, RREP DYMOcast RE with A flag: Route Request Unicast RE: Route Reply RE packet format 2
3
DYMO – Route discovery Comparison 3 DSRAODVDYMO Path way Bi-directionOptional bi- direction Bi-direction Seq. number XOO Message type RREQ, RREP RE Message information Path- accumulation No path- accumulation Optional path- accumulation The other features Caching Multi-path Pre-cursor listHandling unsupportable message, Fixed control packet header
4
Flooding Advantages Simplicity May be more efficient than other protocols when rate of information transmission is low enough Potentially higher reliability of data delivery Multiple path Disadvantages Potentially, very high overhead Potentially lower reliability of data delivery Flooding uses broadcasting -- hard to implement reliable broadcast delivery without significantly increasing overhead –Broadcasting in IEEE 802.11 MAC is unreliable nodes J and K may transmit to node D simultaneously, resulting in loss of the packet 4
5
Flooding of Control Packets Used for route discovery How to reduce the scope of the route request flood ? LAR Query localization How to reduce redundant broadcasts ? The Broadcast Storm Problem 5 Collision!
6
TORA: Temporally-Ordered Routing Algorithm [7-12] A source-initiated on- 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 6
7
TORA Route Maintenance When a partition is detected, all nodes in the partition are informed, and link reversals in that partition cease 7
8
LAR: Location-Aided Routing [7-13] Utilizes the location information (form GPS) to reduce the control packets overhead Flooding is restricted to a small RequestZone LAR1 algorithm 8 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
9
DREAM : Distance Routing Effect Algorithm for Mobility 9
10
ABR: Associativity-Based Routing [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 10
11
SSA: Signal Stability Based Adaptive Routing [7-15] Similar to DSR Signal strength is measure for determining signal stability Strong/stable link Weak/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 11
12
Hybrid Routing Protocols 12
13
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 Intra-zone routing (IARP): employs proactive routing Inter-zone routing (IERP): uses reactive routing 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 13
14
ZHLS: Zone-Based Hierachical Link 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 Hierarchical address: (zone ID, node ID) Zone-level connectivity Zone LSP are propagated by the gateway nodes 14
15
Hierarchical Routing Protocols 15
16
HSR: Hierarchical State Routing [7-23] A distributed multi-level hierarchical routing protocol Employs clustering at different levels Clustering enhances resource allocation and mgmt e.g) allocation of different frequency or spreading codes to different clusters Physical clustering, logical clustering Link state information is broadcast within the cluster at regular intervals Cluster leader exchanges the topology and link state routing information with neighbor clusters 16
17
FSR: Fisheye State Routing [7-23] To reduce information to represent graphical data for reducing routing overhead Keep accurate information about near nodes, but not- so-accurate information about far-away nodes Hybrid approach Link-level information exchange: use distance vector protocol Network topology information : link state protocol Frequency of exchange decreases with an increase in scope 17
18
Power-Aware Routing Protocols 18
19
Power-Aware Routing Metrics Minimal energy consumption per packet Maximize network connectivity Minimum variance in node power levels Distribute the load among all bodes Minimum cost per packet Remaining battery charge cost factor for routing Minimize maximum node cost Minimize 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 node 19
20
Power-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 sequence number 20
Similar presentations
© 2025 SlidePlayer.com. Inc.
All rights reserved.