Why System Registered with Red Hat Subscription Manager is not able to pull repositories?

Issue

• why System Registered with Red Hat Subscription Manager is not able to pull repositories ?
• /var/log/rhsm/rhsm.log show below traceback:

Traceback (most recent call last):
  File "/usr/share/rhsm/subscription_manager/certmgr.py", line 99, in update
    updates += lib.update()
  File "/usr/share/rhsm/subscription_manager/certlib.py", line 61, in update
    return self._do_update()
  File "/usr/share/rhsm/subscription_manager/cache.py", line 49, in _do_update
    return profile_mgr.update_check(self.uep, consumer_uuid)
  File "/usr/share/rhsm/subscription_manager/cache.py", line 214, in update_check
    if not uep.supports_resource(PACKAGES_RESOURCE):
  File "/usr/lib64/python2.6/site-packages/rhsm/connection.py", line 575, in supports_resource
    self._load_supported_resources()
  File "/usr/lib64/python2.6/site-packages/rhsm/connection.py", line 562, in _load_supported_resources
    resources_list = self.conn.request_get("/")
  File "/usr/lib64/python2.6/site-packages/rhsm/connection.py", line 437, in request_get
    return self._request("GET", method)
  File "/usr/lib64/python2.6/site-packages/rhsm/connection.py", line 387, in _request
    conn.request(request_type, handler, body=body, headers=headers)
  File "/usr/lib64/python2.6/httplib.py", line 914, in request
    self._send_request(method, url, body, headers)
  File "/usr/lib64/python2.6/httplib.py", line 951, in _send_request
    self.endheaders()
  File "/usr/lib64/python2.6/httplib.py", line 908, in endheaders
    self._send_output()
  File "/usr/lib64/python2.6/httplib.py", line 780, in _send_output
    self.send(msg)
  File "/usr/lib64/python2.6/httplib.py", line 739, in send
    self.connect()
  File "/usr/lib64/python2.6/site-packages/M2Crypto/httpslib.py", line 73, in connect
    raise error
timeout: timed out