cassandra - cqlsh Connection refused -

when ever cassandra cqlsh connection error follows:

connection error: ('unable connect servers', {'127.0.0.1': error(111, "tried connecting [('127.0.0.1', 9042)]. last error: connection refused")})

another solution, type cqlsh <listen_address> [<port>] if not set 127.0.0.1 or localhost