IP switching over fast ATM cell transport (IPSOFACTO): IP multicast over wireless ATM

IPSOFACTO is an IP switching technique that directly maps IP flows to ATM VCs without any signalling. This paper extends IP multicast using IPSOFACTO over wireless ATM. A wireless ATM system consists of a fixed core network and a shared wireless access link for mobile terminals. Unlike point-to-point ATM links within the fixed/wired network, wireless ATM link uses a common VC space for all mobile terminals and the medium access (MAC) protocol supports shared multiple access on the downlink, but only point-to-point unicast access on the uplink. This paper describes how IP multicast can be natively supported on such WATM links using IPSOFACTO along with specific extensions to the Internet Group Management Protocol (IGMP). In addition, a cell-level error recovery scheme at the DLC (data link control) layer is described to enhance the packet-level throughput of the transport layer.