The WSR88D products and base data, like many other meteorological data, are currently distributed on the network via "unicasting". That is a copy of the data is send to each receiver separately. If multiple receivers request the same data, multiple copies of the same data must be sent through the network. In order to efficiently use the available bandwidth, which is often a precious resource, we need to consider the possibility of using multicasting.

Packet multicasting is supported by most of the current network infrastructure hardware. The technique is, however, not yet used for radar data distribution mainly because of the reliability concern. Although reliable unicasting protocol (e.g. TCP) has been available for many years, there is so far no standard protocol for reliable multicasting. Several experimental protocols have been proposed. These protocols are mostly designed for applications with large number of receivers and less strict reliability requirement.

Since FAA has made a decision to receive WSR88D products via multicasting, the Radar Operations Center of NWS is currently working on designing and implementing a reliable multicasting protocol for distributing radar products. The protocol is specifically designed for distributing operational data with acceptable high reliability. In this paper, we will present the protocol, the implementation and how this is used in WSR88D product distribution.