diff --git a/.travis.yml b/.travis.yml
index 32e6929..6784be1 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -1,13 +1,13 @@
 language: python
 
 python:
-- 2.7
-- 3.4
-- 3.5
+  - 2.7
+  - 3.4
+  - 3.5
 
 install:
-- pip install .
-- pip install -r requirements-dev.txt
+  - pip install tox-travis
+  - pip install coveralls
 
 deploy:
   provider: pypi
@@ -19,8 +19,8 @@ deploy:
     branch: master
 
 script:
-- py.test --cov-report= --cov=napalm_nxos test/
-- pylama .
+  - tox
 after_success:
-- coveralls
-- if [ $TRAVIS_TAG ]; then curl -X POST https://readthedocs.org/build/napalm; fi
+  - coveralls
+  - if [ $TRAVIS_TAG ]; then curl -X POST https://readthedocs.org/build/napalm; fi
+
diff --git a/napalm_nxos/nxos.py b/napalm_nxos/nxos.py
index 8791219..23d5e31 100644
--- a/napalm_nxos/nxos.py
+++ b/napalm_nxos/nxos.py
@@ -56,6 +56,7 @@ def __init__(self, hostname, username, password, timeout=60, optional_args=None)
         self.fc = None
         self.changed = False
         self.replace_file = None
+        self.merge_candidate = ''
 
         if optional_args is None:
             optional_args = {}
@@ -212,11 +213,12 @@ def load_merge_candidate(self, filename=None, config=None):
         if not filename and not config:
             raise MergeConfigException('filename or config param must be provided.')
 
+        self.merge_candidate += '\n'  # insert one extra line
         if filename is not None:
             with open(filename, "r") as f:
-                self.merge_candidate = f.read()
+                self.merge_candidate += f.read()
         else:
-            self.merge_candidate = config
+            self.merge_candidate += config
 
     def _send_file(self, filename, dest):
         self.fc = FileCopy(self.device, filename, dst=dest.split('/')[-1])
@@ -261,13 +263,21 @@ def _get_merge_diff(self):
             if line not in running_lines and line:
                 if line[0].strip() != '!':
                     diff.append(line)
-        self.merge_candidate = '\n'.join(diff)
+        return '\n'.join(diff)
+        # the merge diff is not necessarily what needs to be loaded
+        # for example under NTP, as the `ntp commit` command might be
+        # alread configured, it is mandatory to be sent
+        # otherwise it won't take the new configuration - see #59
+        # https://github.com/napalm-automation/napalm-nxos/issues/59
+        # therefore this method will return the real diff
+        # but the merge_candidate will remain unchanged
+        # previously: self.merge_candidate = '\n'.join(diff)
 
     def compare_config(self):
         if self.loaded:
             if not self.replace:
-                self._get_merge_diff()
-                return self.merge_candidate
+                return self._get_merge_diff()
+                # return self.merge_candidate
             diff = self._get_diff(self.fc.dst)
             return diff
         return ''
@@ -293,7 +303,7 @@ def _load_config(self):
         except ConnectionError:
             # requests will raise an error with verbose warning output
             return True
-        except:
+        except Exception:
             return False
         return True
 
@@ -307,6 +317,7 @@ def commit_config(self):
             else:
                 try:
                     self._commit_merge()
+                    self.merge_candidate = ''  # clear the merge buffer
                 except Exception as e:
                     raise MergeConfigException(str(e))
 
@@ -321,6 +332,8 @@ def _delete_file(self, filename):
         self.device.show('no terminal dont-ask', raw_text=True)
 
     def discard_config(self):
+        if self.loaded:
+            self.merge_candidate = ''  # clear the buffer
         if self.loaded and self.replace:
             try:
                 self._delete_file(self.fc.dst)
@@ -812,7 +825,8 @@ def traceroute(self,
                    destination,
                    source=c.TRACEROUTE_SOURCE,
                    ttl=c.TRACEROUTE_TTL,
-                   timeout=c.TRACEROUTE_TIMEOUT):
+                   timeout=c.TRACEROUTE_TIMEOUT,
+                   vrf=c.TRACEROUTE_VRF):
         _HOP_ENTRY_PROBE = [
             '\s+',
             '(',  # beginning of host_name (ip_address) RTT group
diff --git a/napalm_nxos/templates/delete_ntp_peers.j2 b/napalm_nxos/templates/delete_ntp_peers.j2
index cee41bf..85f89c7 100644
--- a/napalm_nxos/templates/delete_ntp_peers.j2
+++ b/napalm_nxos/templates/delete_ntp_peers.j2
@@ -1,3 +1,4 @@
 {% for peer in peers %}
 no ntp peer {{peer}}
 {% endfor %}
+ntp commit
diff --git a/napalm_nxos/templates/delete_ntp_servers.j2 b/napalm_nxos/templates/delete_ntp_servers.j2
index 38accdf..ed15abf 100644
--- a/napalm_nxos/templates/delete_ntp_servers.j2
+++ b/napalm_nxos/templates/delete_ntp_servers.j2
@@ -1,3 +1,4 @@
 {% for server in servers %}
 no ntp server {{server}}
 {% endfor %}
+ntp commit
diff --git a/napalm_nxos/templates/delete_users.j2 b/napalm_nxos/templates/delete_users.j2
new file mode 100644
index 0000000..41e0a37
--- /dev/null
+++ b/napalm_nxos/templates/delete_users.j2
@@ -0,0 +1,16 @@
+{%- for user_name, user_details in users.items() %}
+{%- if user_details -%}
+{%- if user_details.get('sshkeys') %}
+{%- for sshkey in user_details.sshkeys %}
+no username {{user_name}} sshkey {{ sshkey }}
+{%- endfor %}
+{%- endif %}
+{%- if user_details.get('password') %}
+no username {{user_name}} password
+{%- endif %}
+{%- if user_details.get('level') %}
+no username {{user_name}} role priv-{{user_details.level}}
+{%- endif %}
+{%- endfor %}
+{%- else -%}
+{%- endif -%}
diff --git a/napalm_nxos/templates/set_ntp_peers.j2 b/napalm_nxos/templates/set_ntp_peers.j2
index 1dd886b..57b16ed 100644
--- a/napalm_nxos/templates/set_ntp_peers.j2
+++ b/napalm_nxos/templates/set_ntp_peers.j2
@@ -1,3 +1,4 @@
 {% for peer in peers %}
 ntp peer {{peer}}
 {% endfor %}
+ntp commit
diff --git a/napalm_nxos/templates/set_ntp_servers.j2 b/napalm_nxos/templates/set_ntp_servers.j2
index 1cebc15..b4758d2 100644
--- a/napalm_nxos/templates/set_ntp_servers.j2
+++ b/napalm_nxos/templates/set_ntp_servers.j2
@@ -1,3 +1,4 @@
 {% for server in servers %}
 ntp server {{server}}
 {% endfor %}
+ntp commit
diff --git a/napalm_nxos/templates/set_users.j2 b/napalm_nxos/templates/set_users.j2
new file mode 100644
index 0000000..c49f783
--- /dev/null
+++ b/napalm_nxos/templates/set_users.j2
@@ -0,0 +1,13 @@
+{%- for user_name, user_details in users.items() %}
+{%- if user_details.get('sshkeys') %}
+{%- for sshkey in user_details.sshkeys %}
+username {{user_name}} sshkey {{ sshkey }}
+{%- endfor %}
+{%- endif %}
+{%- if user_details.get('password') %}
+username {{user_name}} password 5 {{user_details.password}}
+{%- endif %}
+{%- if user_details.get('level') %}
+username {{user_name}} role priv-{{user_details.level}}
+{%- endif %}
+{%- endfor %}
diff --git a/requirements-dev.txt b/requirements-dev.txt
index 6b6a977..f42a250 100644
--- a/requirements-dev.txt
+++ b/requirements-dev.txt
@@ -4,4 +4,6 @@ pytest-cov
 pytest-json
 pytest-pythonpath
 pylama
+flake8-import-order
 -r requirements.txt
+
diff --git a/setup.cfg b/setup.cfg
index 559b516..b946a3e 100644
--- a/setup.cfg
+++ b/setup.cfg
@@ -1,15 +1,16 @@
 [pylama]
 linters = mccabe,pep8,pyflakes
 ignore = D203,C901
+skip = build/*,.tox/*
 
 [pylama:pep8]
 max_line_length = 100
 
-[tool:pytest]
-addopts = --cov=./ -vs
+[pytest]
+addopts = --cov=napalm_nxos --cov-report term-missing -vs --pylama
 json_report = report.json
 jsonapi = true
 
 [coverage:run]
-include =
-  napalm_nxos/*
+source = napalm_nxos
+
diff --git a/tox.ini b/tox.ini
new file mode 100644
index 0000000..5ae5d81
--- /dev/null
+++ b/tox.ini
@@ -0,0 +1,9 @@
+[tox]
+envlist = py27,py34,py35
+
+[testenv]
+deps =
+    -rrequirements-dev.txt
+
+commands=
+   py.test