040.92: EARN Regionalization by Frode Greisen The way EARN (and BITNET) networks function is by a store-and- forward system with permanent connections and fixed routing tables in the nodes, which are hosts running the IBM NJE protocol. Originally, the routing was a pure tree structure. About 18 months ago, EARN decided on a regionalization plan by which 13 core nodes were connected essentially all to all. This was done by setting up virtual NJE over IP links using available IP lines for research and education in Europe and across the Atlantic. A similar regionalization took place in BITNET in the so-called BITNET-II project somewhat earlier. When traffic conditions are good (i.e., when there are no link failures or traffic overload on a particular path), then mail and small files typically have end-to-end transfer times of a few seconds for international traffic involving half-a-dozen hops. When traffic conditions are bad, then files are queued at the intermediate hosts and the transfer can take minutes or longer. For the last year or so, EARN staff has monitored queue sizes at the international nodes. It has been very encouraging to note that from February 1991 to February 1992 the average number of files queued has been reduced by 67% while there was a slight increase in total traffic. The number of files queued is only an indirect service measure but there is no doubt that the end users have experienced a significant improvement in transmission times and we largely assign this improvement to the regionalization described above.