ORA-12547: TNS:lost contact

Hi Experts
i have getting below error at the time of database conection can you please suggest me the solution

Thanks in advanced.

[oracle@ebs db]$ sqlplus '/as sysdba'

SQL*Plus: Release 11.1.0.7.0 - Production on Mon Feb 4 13:07:46 2013

Copyright (c) 1982, 2008, Oracle.  All rights reserved.

ERROR:
ORA-12547: TNS:lost contact

for above sitiuation i have done below steps but no use

1)

 

$ cd $ORACLE_HOME/bin

$ ls -ltr oracle

-rwxr-xr-x    1 oracle   dba       136803483 Mar 16 20:32 oracle

$

 

$ chmod 6751 oracle

$ ls -ltr oracle

-rwsr-s--x    1 oracle   dba       136803483 Mar 16 20:32 oracle<br/><br/><br/>2)<br/><br/>ulimit -a


3) relink oracle

4) relink all

But no use can you please any one share other steps.