Page 2 Lecture Notes in Computer Science 2865 Edited by G. Goos ...
Page 2 Lecture Notes in Computer Science 2865 Edited by G. Goos ...
Page 2 Lecture Notes in Computer Science 2865 Edited by G. Goos ...
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Extend<strong>in</strong>g Seamless IP Multicast Edge-Coverage 85<strong>in</strong>clude ad-hoc wireless elements with<strong>in</strong> the access <strong>in</strong>frastructure as a naturalevolution towards ‘beyond 3G’ systems. In this ad hoc fr<strong>in</strong>ge, a user term<strong>in</strong>alemploys those of other users as relay po<strong>in</strong>ts to provide multi-hop paths betweenmobile nodes and the fixed access network architecture.The provision of an <strong>in</strong>tegrated IP multicast service <strong>in</strong> such an heterogeneousscenario consist<strong>in</strong>g on traditional IP core networks <strong>in</strong>terconnect<strong>in</strong>g a variety ofwireless and wired access networks and technologies is extremely complex. Thereare specific solutions for wireless ad hoc networks, but the real challenge is theireffective and efficient <strong>in</strong>tegration with (fixed) IP multicast protocols to achieve aseamless IP multicast service <strong>in</strong> which group members from any of these networktypes can take part <strong>in</strong> the same IP multicast session. Furthermore, mobile nodesshould be allowed to move among these types of networks without any servicedisruption.To our knowledge, for the specific problem of IP multicast <strong>in</strong>terwork<strong>in</strong>g betweenIP access networks and wireless and mobile ad hoc networks, there arenot satisfactory solutions so far. The typical <strong>in</strong>tra-doma<strong>in</strong> IP multicast protocolsfor fixed networks (i.e. IGMPv2[2] for multicast group membership and PIM-SM[3] for IP multicast rout<strong>in</strong>g) are not able to deal with the quick and unpredictablel<strong>in</strong>k changes which characterise ad hoc networks. They would consumetoo much overhead to keep updated distribution paths <strong>in</strong> such variable topologies.In addition, multicast ad hoc rout<strong>in</strong>g protocols like CAMP[4], ODMRP[5],and ADMR[6] among others, <strong>in</strong>corporate specific functionality which enablesthem to cope with the particular characteristics of ad hoc networks but theyare only suitable for isolated ad hoc networks. These protocols do not provideany means to <strong>in</strong>teroperate with the protocols used <strong>in</strong> the fixed IP networks andthey do not support the attachment of standard IP multicast nodes to the adhoc extension. In fact, the only few proposals to connect ad hoc networks tothe Internet, like the one <strong>by</strong> Lei and Perk<strong>in</strong>s[7] have only considered the case ofunicast traffic.In this paper we propose an <strong>in</strong>tegrated IP Multicast solution for ad hoc networkextensions consist<strong>in</strong>g of a novel IP multicast architecture and the MulticastMAnet Rout<strong>in</strong>g Protocol (MMARP). MMARP is a new multicast ad hoc rout<strong>in</strong>gprotocol based on the same basic mechanisms as other ad hoc multicast rout<strong>in</strong>gprotocols. However, it <strong>in</strong>corporates additional functionalities to deal with thecomplexity of support<strong>in</strong>g traditional IP nodes whilst <strong>in</strong>teroperat<strong>in</strong>g smoothlywith fixed IP networks. MMARP nodes are able to <strong>in</strong>tercept and process standardIP multicast messages. They further permit standard IP nodes to seamlesslyparticipate <strong>in</strong> IP multicast communications as they do when attached to a fixedIP network. The novelty of our approach is not only the provision of such an<strong>in</strong>tegrated IP multicast solution, but also the way <strong>in</strong> which the functions aredivided among the fixed and ad hoc nodes so that the <strong>in</strong>terwork<strong>in</strong>g is achievedwithout a noticeable impairment <strong>in</strong> the overall performance.The rema<strong>in</strong>der of the paper is organised as follows: section 2 comments onthe problems, requirements, and proposed architecture for ad hoc access networkextensions. A detailed description of the MMARP protocol is given <strong>in</strong> section 3.