Network ports need to be opened in your firewall in context of RHEV

Below services or operations happens on below mentioned ports.. So make sure that, those are opened..
54321                                : vdsm

22                                       : ssh

5634 – 6166                        : guest console access ports

49152 – 49216                   : VM migration port range

32023                                : Spice  usb redirection

It is already mentioned here .

http://docs.redhat.com/docs/en-US/Red_Hat_Enterprise_Linux/5/html/Hypervisor_Deployment_Guide/chap-Deployment_Guide-Security_topics.html