Page 2 Lecture Notes in Computer Science 2865 Edited by G. Goos ...

88 P.M. Ruiz et al.Access NetworkCoreAS 6110RPMIGAS 766MSDP/MBGP DVMRP, PIM, IGMP MMARP IGMPRPPIM-SM MSDPGIGMPIP IPL2/PH L2/PHYARPIM-SMIGMPIP IPL2/PH L2/PHYMIGAppTCP/UDPMMARPIGMPIPL2/PHY...Ad hocAppTCP/UDPMMARIGMPIPL2/PHYStd-IPAppTCP/UDPIGMPIPL2/PHYFig. 1. Proposed multicast architectureThe AR and RP nodes in the figure represent standard multicast-enabledrouters running PIM-SM. ‘Ad hoc’ represent pure ad hoc nodes and ‘Std IP’represnts a standard IP multicast-enabled mobile host. The protocol providingefficient paths between the nodes within the ad hoc network fringe is theMMARP protocol presented below. From the point of view of the core networkand the AR, the ad hoc fringe is seen just as another BMA subnet (i.e. groupmembership are being dynamically updated by IGMP Report messages receivedby the ARs).3 The MMARP ProtocolThe MMARP protocol is especially designed for mobile ad hoc networks(MANETs). It is fully compatible with the standard IP Multicast model andit allows standard IP nodes to take part in multicast communications withoutrequiring any change because MMARP supports the IGMP protocol as a meansto interoperate both with access routers and standard IP nodes. The interoperationwith access routers is performed by the Multicast Internet Gateways(MIGs) which are the ad hoc nodes situated just one hop away from the fixednetwork. Every MMARP node may become a MIG at any time. The only differencebetween a MIG and a normal MMARP node is that the MIG is responsiblefor notifying the access routers about the groups memberships within the ad hocfringe. The mechanism allows MMARP to work with any IP multicast routingprotocol in the access network and, therefore, it shields the MMARP operationfrom the protocols performing the intra-domain or inter-domain multicastrouting.For the remaining text we use the terms standard IP source or standard IPreceiver to refer to a traditional IP Multicast source or receiver and we use theterm ad hoc sender or ad hoc receiver to refer to pure ad hoc nodes.