A small network will usually work just as well if every peer is an Ultrapeer.

However, instead of modifying allowConnection() (which is a bad idea because you don't really want clients that think they are leafs to connect to each other), just put the static addresses of a few seed Ultrapeers into LimeWire's gnutella.net file (and remove all other addresses). It's even possible to hardcode some of those addresses in the HostCatcher.java file.

If you force supernode mode for two or three seed ultrapeers, the others should go into leaf mode automatically.

- By the way, you should really consider modifying the number of ultrapeer connections, because an outdegree of 15 is probably far too much for a small network.

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