This isn't rocket science, why won't RHL 7.x let anything talk to it or talk to anything else?
On same segment, same subnet, my 6.2 Sendmail server will ping, telnet, Sendmail, etc. to anything but my 7.x servers. My 7.x will not ping, telnet, etc. to anything. I've disabled iptables and ipchains. All machines are in each others' hosts file and will resolve IP addresses. Default server installs on all. Sometimes my Sendmail 6.2/7.2 servers will talk, sometimes they won't.
This is rediculous, give a machine an IP address and it should be able to at least ping and telnet.