Solaris client NFS mount with cachefs to RHEL server

[Marcelino Mata]

I am trying to NFS mount a folder from RHEL 3 server (Update6) for
Solaris client.  Solaris has no problems with standard NFS mount or when
NFS automounter is used but if I try to use the cachefs option, I get
"permission denied".
 
I think the problem is NFS V2 UDP/TCP or NFS V3 UDP/TCP issue.
Unfortunately, Solaris cachefs mount options does not have the option of
restricting mount operation to any particular protocol. 
 
 How do I disable NFS V2 UDP and/or TCP or NFS V3 TCP from the Redhat
server? I tried something from NFS sourceforge site but it did not seem
to apply to Redhat 3 (or I did it wrong).
 
Marcelino