Administrative Issues CMPE 257 Wireless and Mobile Networking Class newsgroup server Ucsc class cpme257 Project 1 graded Spring 2003 Status updates for project2 Week 5 First update due 05 13 Second update due 05 27 CMPE 257 Spring 2003 1 2 Multicast Communication in Ad Hoc Networks Multicast routing classification Group Communications Routing Protocols Conference Scenario Rescue Disaster Scenario Battlefield Scenario Table Driven Proactive AMRoute On Demand Reactive CAMP WRP MAODV 3 AMRIS ODMRP 4 Overview Multicasting A multicast group is defined with a unique group identifier ODMRP M AODV CAMP AMRIS Flooding and Variations Nodes may join or leave the multicast group anytime In traditional networks the physical network topology does not change often In MANET the physical topology can change often 5 6 On Demand Multicast Routing Protocol ODMRP Multicasting in MANET Need to take topology change into account when designing a multicast protocol ODMRP requires cooperation of nodes wishing to send data to the multicast group To construct the multicast mesh A sender node wishing to send multicast packets periodically floods a Join Query packet throughout the network Several new protocols have been proposed for multicasting in MANET Periodic transmissions are used to update the routes 7 8 On Demand Multicast Routing Protocol ODMRP On Demand Multicast Routing Protocol ODMRP Assume that S is a sender node Each multicast group member on receiving a Join Query broadcasts a Join Table to all its neighbors Join Table contains sender S next node N pairs next node N denotes the next node on the path from the group member to the multicast sender S S N M A D C B Join Query When node N receives the above broadcast N becomes member of the forwarding group T When node N becomes a forwarding group member it transmits Join Table containing the entry S M where M is the next hop towards node S Multicast group member 9 On Demand Multicast Routing Protocol ODMRP N S On Demand Multicast Routing Protocol ODMRP A M S Join Query Join Query 10 N D C A Join Table S M Join Query T M B T D C B Join Table S C Multicast group member Multicast group member 11 12 On Demand Multicast Routing Protocol ODMRP Join Table S N S F M N On Demand Multicast Routing Protocol ODMRP Join Table S S N A S F M A F C B F T F C D B T D Join Table S N F marks a forwarding group member Multicast group member 13 On Demand Multicast Routing Protocol ODMRP 14 On Demand Multicast Routing Protocol ODMRP F S N M F A S F T D N M A F F C Join Table T C F F C B T D Join Table T T Join Table T D Join Table T C B Join Query T Multicast group member Multicast group member 15 16 ODMRP Multicast Delivery ODMRP No explicit join or leave procedure A sender broadcasts data packets to all its neighbors A sender wishing to stop multicasting data simply stops sending Join Query messages Members of the forwarding group forward the packets A multicast group member wishing to leave the group stops sending Join Table messages Using ODMRP multiple routes from a sender to a multicast receiver may exist due to the mesh structure created by the forwarding group members A forwarding node ceases its forwarding status unless refreshed by receipt of a Join Table message Link failure repair taken into account when updating routes in response to periodic Join Query floods from the senders 17 AODV Multicasting Royer00Mobicom 18 AODV Group Sequence Number Each multicast group has a group leader Group leader is responsible for maintaining group sequence number which is used to ensure freshness of routing information In our illustrations we will ignore the group sequence numbers Similar to sequence numbers for AODV unicast However note that a node makes use of information received only with recent enough sequence number First node joining a group becomes group leader A node on becoming a group leader broadcasts a Group Hello message 19 20 AODV Multicast Tree Joining the Multicast Tree AODV Multicast tree links Group leader E Group leader E L L C C J J G G H D K H D K A A B B N Group and multicast tree member N N wishes to join the group it floods RREQ Route Request RREQ Tree but not group member 21 Joining the Multicast Tree AODV 22 Joining the Multicast Tree AODV Group leader E Group leader E L L C C J J G H G D K H A D K A B N N wishes to join the group Route Reply RREP B N N wishes to join the group Multicast Activation MACT 23 24 Joining the Multicast Tree AODV Sending Data on the Multicast Tree Data is delivered along the tree edges maintained by the Multicast AODV algorithm Multicast tree links Group leader E L C If a node which does not belong to the multicast group wishes to multicast a packet J It sends a non join RREQ which is treated similar in many ways to RREQ for joining the group As a result the sender finds a route to a multicast group member Once data is delivered to this group member the data is delivered to remaining members along multicast tree edges G H D K A B N Group member N has joined the group Tree but not group member 25 Leaving a Multicast Tree AODV 26 Leaving a Multicast Tree AODV Multicast tree links Group leader E L C J J wishes to leave the group Since J is not a leaf node it must remain a tree member L C J G H Group leader E J has left the group G D K H A D K A B B N N 27 28 Leaving a Multicast Tree AODV Leaving a Multicast Tree AODV Group leader E Group leader E L L C C J J G G H D K A H A MACT prune B MACT prune D K B N Node N has removed itself from the multicast group N wishes to leave the multicast group N Now node K has become a leaf and K is not in the group So node K removes itself from the tree as well 29 Leaving a Multicast Tree AODV Handling a Link Failure AODV Multicasting When a link X Y on the multicast tree breaks the node that is further away from the leader is responsible to reconstruct the tree say node X Group leader E L C 30 J G H Node X which is further downstream transmits a Route Request RREQ D K A Only nodes which are closer to the leader than node X s last known distance are allowed to send RREP in response to the RREQ to prevent nodes that are further downstream from node X from responding B N Nodes N and K are no more in the multicast tree 31 32 Handling Partitions AODV Merging Partitions AODV When failure of link X Y …