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An Interest-Driven Approach to Integrated Unicast and Multicast Routing in MANETs. Protocol for Routing in Interest-defined Mesh Enclaves PRIME. Rolando Menchaca-Mendez J.J. Garcia-Luna-Aceves 280N Seminar: 4/28/2008 - Santa Cruz, CA. Presentation Outline. Introduction
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An Interest-Driven Approach to Integrated Unicast and Multicast Routing in MANETs Protocol for Routing in Interest-defined MeshEnclaves PRIME Rolando Menchaca-Mendez J.J. Garcia-Luna-Aceves 280N Seminar: 4/28/2008 - Santa Cruz, CA
Presentation Outline • Introduction • The Protocol for Routing in Interest-defined MeshEnclaves (PRIME) • Mesh Activation and Deactivation • Mesh Establishment and Maintenance • Opportunistic Transmission of Mesh Announcements • Enclaves vs. Meshes • Packet Forwarding and Local Repairs • Core Election • Adaptive Strategies • Performance Results • Conclusions
Introduction • MANET applications require point-to-point andmany-to-many communication, and very few destinations aresuch that a large percentage of the nodes in the network have interestin them. • These applicationrequirements are in stark contrast with the way in which today's MANETrouting protocols operate. • They supporteither unicast routing or multicast routing • Proactive and on-demand routing protocols for unicasting andmulticasting proposed to date are such that the network is floodedfrequently • This is the case even when the protocolsmaintain routing information on demand (e.g., AODV and ODMRP)
Introduction • The main contribution of this work is to introduce an integrated frameworkfor routing in MANETs. • The samecontrol signaling is used to support unicast and multicast routing, • The distinction between on-demand and proactive signaling forrouting is eliminated and interest-driven signaling is used instead. • Interest-defined mesh enclaves are established andmaintained • Such meshes are connected components of a MANET overwhich control signaling and data packets for unicast ormulticast flows are disseminated.
PRIME: Mesh Activation and Deactivation • The first source that becomes active for a given unicast ormulticast destination sends its first data packet piggybacked in amesh-activation request (MR) • A MR contains,among other fields, an horizon threshold and the persistence of theinterest • Destinations, relaysneeded between them, and interested sources remain active for as longas there are active sources in the connected component of thenetwork.
PRIME: Mesh Establishment and Maintenance • Once a destination becomes active, it startsadvertising its existence using mesh announcements (MA). • A MA contains the following fields: • Message type • Destination address • Core address • unicastdestination, core of a multicast group, a flag that indicates that the MA isa partition confirmation request, or a neighbor request • Sequencenumber • Distance to the destination • Next hop • Membership code • mesh member, receiver, both, or regular node; in the case of a unicast flow, the membership code isused to indicate the scope of the dissemination of a MA; namely,flood or restricted to the enclave
PRIME: Mesh Establishment and Maintenance Rg uses the transmission of d’s MA as an implicit ACK e Receiver Rg forces its parent to join the multicast mesh a d Core Node b selects the core as its parent or next hop c Rg b Transmission of MA f Parent Pointer
Mesh composed of braided paths 3 1 4 2 2 3 1 1 2 Multicast Mesh PRIME: Mesh Establishment and Maintenance A similar structure would be used to route unicast packets from s to the core
PRIME:Enclaves vs. Meshes The frequency with which multicast-MAs are forwarded outside of the enclave decreases exponentially MAs are not forwarded beyond a unicast enclave
PRIME: Packet Forwarding • Upon reception of a data packet, nodes first check for a hit in their datapacket cache • If the (sender's address, seq. num.) pair is already in the cache, the packet is silently dropped. • Otherwise, the receiving node inserts the pair in its cache anddetermines whether it has to relay the data packet or not, and passesthe packet to the upper layers if it is also a receiver for the flow. • The two rules used to decide when to relay a multicast data packet are: • First, if the node is part of the multicast mesh it broadcasts the packet without furtherprocessing. • Second, a node located outside of the multicast meshrelays a data packet it receives from a neighbor if it was selectedby that neighbor as one of its next hops to the core. • data packetstravel along meshes consisting of braided paths, until they reacheither the first mesh member or the core
PRIME: Packet Forwarding and Local Repairs • Unicast data packets are also routed using meshes composed of braided shortest paths from sources to destinations • Nodes forward a unicast datapacket they receive if they were selected as a next hop to the destination bythe previous relay of the data packet • Nodes located outside of the multicast mesh of a groupemploy the transmission of data packets bytheir next hops as implicit ACKs. • If a node fails to receive threeconsecutive implicit ACKs from a neighbor, then it removes that node fromthe neighborhood list and takes one of three actions to locallyrepair the braided path to the core or unicast destination.
b PRIME: Packet Forwarding and Local Repairs • If after removing the neighbor from the neighborhood list, the currentnode is left with no paths to the core, then it broadcasts a neighborrequest. • Neighbor requests are replied by nodes with MAs that advertisetheir latest routing information regarding a given destination. d a
PRIME: Local Repairs • If the distanceto the destination of the current node increases, then it broadcasts anew MA that informs other nodes of its new state. • This way, a new set ofneighbors will beselected as this node's next hops and previous upstreamnodes may select new nodes as their next hops to the destination. b d a e c
PRIME: Local Repairs • If the distance to the destination of the current node does notincrease, then it checks its neighborhood list for other potentialnext hops to the destination. • If atleast one of these potential nodes exists, then a MA is transmitted toinform the potential next hop that it has been selected as nexthop. • If no potential nodes are found, no further action is taken. b e d a c
PRIME: Core Election • Core elections are held only if the MR contains a multicastaddress. • Upon reception of a MR, a receiver first determines whetherit has received a MA from the core of the multicast group within thelast two MA-intervals. • If the node has, no furtheraction in this regard is needed. • Otherwise, the receiver considersitself the core of the group and starts transmitting MAs to itsneighbors, stating itself as the core of the group. • Nodes propagateMAs based on the best announcements they receive from theirneighbors. • A MA with a higher core id is considered better than onewith a lower core id. • Eventually, eachconnected component has only one core. • A core election is also held if the network is partitioned. • A node detects a partition if it does notreceive a fresh MA from the core for three consecutiveMA-intervals and if it has received data packets withinthe last four MA-intervals.
PRIME: Adaptive Strategies • Nodes employ informationcollected at the MAC layer to select the strategy that best fits thenodes' perceived channel conditions. • We use the following three strategies to take advantage of that information: • Adjust the size of the mesh • Adjust the mesh dynamics • Adjust timers
Performance Results • We present simulation results comparing PRIME against ODMRPand PUMA for the case of multicast traffic, as well as against AODVwith ODMRP and OLSR with ODMRP for the case of combined unicast andmulticast traffic. • We usepacket delivery ratio, generalized groupdelivery ratio, end-to-end delay, and total overhead as ourperformance metrics. • The generalized group delivery ratio is anextension of the group reliability metric, in which a packet is considered as delivered, ifand only if it is received by a given proportion of the receivers, • This metric emphasizes the importance of groupdelivery by not considering packets that are received by a smallsubset of the group members.
Conclusions • We have shown by example that it is possible and perhaps desirable tosupport the dissemination of information for end user applicationsusing a single routing protocol, and that interest-driven routingshould be adopted for MANETs • PRIME redefines howsignaling is done for routing in MANETs by integrating unicast andmulticast routing using interest-driven establishment of meshes andenclaves. • PRIME establishes meshes (connected components of a MANET)that are activated and deactivated by the presence or absence of datatraffic. • Enclaves confine most of the dissemination of control packetsto those that actually need the information. • This property has apositive impact over the scalability of the protocol, particularly inmedium to large networks in which the members of the same multicastgroup tend to be close by. • The results of a seriesof simulation experiments illustrate that PRIME attains higherdelivery ratios than ODMRP and PUMA for multicast traffic, and higherdelivery ratios than AODV and OLSR for unicast traffic. At the sametime, PRIME induces much less communication overhead and attains lowerdelays than the other routing protocols.
