Unable to mount a NFS share of new installed NFS Server

Issue

• Installed a new RHEL6 system and configured NFS share but the NFS clients are unable to mount the share.

• From the NFS client below output were showing:

 # rpcinfo -p <NFS-SERVER-IP>
 rpcinfo: can't contact portmapper: RPC: Remote system error - No route to host

 # showmount -e <NFS-SERVER-IP>
 clnt_create: RPC: Port mapper failure - Unable to receive: errno 113 (No route to host)