/tomcat-7.0-doc/config/cluster-receiver.html : In the section "Attributes -- Common Attributes", the description of Attribute "port" is slightly diffrent to the facts. It says "port <= bindPort <= port+autoBind", but this should be written "port <= bindPort < port+autoBind". And "port in the range 4000-4100." also shoud be written "port in the range 4000-4099." For example, I try (port=4000, and autoBind=10), then the receiver tried to open port in the range of 4000-4009. It didn't try port 4010.
Thanks for the report. Fixed in trunk and 7.0.x and will be included in 7.0.40 onwards.