diff --git a/gnpy/tools/json_io.py b/gnpy/tools/json_io.py
index ef75aa2d..55c6d795 100644
--- a/gnpy/tools/json_io.py
+++ b/gnpy/tools/json_io.py
@@ -547,7 +547,7 @@ def requests_from_json(json_data, equipment):
         params['format'] = params['trx_mode']
         params['spacing'] = req['path-constraints']['te-bandwidth']['spacing']
         try:
-            nd_list = req['explicit-route-objects']['route-object-include-exclude']
+            nd_list = sorted(req['explicit-route-objects']['route-object-include-exclude'], key=lambda x: x['index'])
         except KeyError:
             nd_list = []
         params['nodes_list'] = [n['num-unnum-hop']['node-id'] for n in nd_list]
diff --git a/tests/test_parser.py b/tests/test_parser.py
index 92afd121..3ff8d888 100644
--- a/tests/test_parser.py
+++ b/tests/test_parser.py
@@ -506,3 +506,71 @@ def test_eqpt_creation(tmpdir):
     # check that all amp in the converted files corresponds to an eqpt line
     for ampuid in jsonconverted.keys():
         assert ampuid in possiblename
+
+
+def test_service_json_constraint_order():
+    """test that the constraints are read in correct order"""
+
+    unsorted_request = {
+        "request-id": "unsorted",
+        "source": "trx Brest_KLA",
+        "destination": "trx Vannes_KBE",
+        "src-tp-id": "trx Brest_KLA",
+        "dst-tp-id": "trx Vannes_KBE",
+        "bidirectional": False,
+        "path-constraints": {
+            "te-bandwidth": {
+                "technology": "flexi-grid",
+                "trx_type": "Voyager",
+                "trx_mode": "mode 1",
+                "spacing": 50000000000.0,
+                "output-power": 0.001,
+                "path_bandwidth": 10000000000.0
+            }
+        },
+        "explicit-route-objects": {
+            "route-object-include-exclude": [
+                {
+                    "explicit-route-usage": "route-include-ero",
+                    "index": 2,
+                    "num-unnum-hop": {
+                        "node-id": "roadm Lorient_KMA",
+                        "link-tp-id": "link-tp-id is not used",
+                        "hop-type": "STRICT"
+                    }
+                },
+                {
+                    "explicit-route-usage": "route-include-ero",
+                    "index": 3,
+                    "num-unnum-hop": {
+                        "node-id": "roadm Vannes_KBE",
+                        "link-tp-id": "link-tp-id is not used",
+                        "hop-type": "STRICT"
+                    }
+                },
+                {
+                    "explicit-route-usage": "route-include-ero",
+                    "index": 1,
+                    "num-unnum-hop": {
+                        "node-id": "roadm Lannion_CAS",
+                        "link-tp-id": "link-tp-id is not used",
+                        "hop-type": "LOOSE"
+                    }
+                },
+                {
+                    "explicit-route-usage": "route-include-ero",
+                    "index": 0,
+                    "num-unnum-hop": {
+                        "node-id": "roadm Brest_KLA",
+                        "link-tp-id": "link-tp-id is not used",
+                        "hop-type": "STRICT"
+                    }
+                }
+            ]
+        }
+    }
+
+    data = {'path-request': [unsorted_request]}
+    rqs = requests_from_json(data, equipment)
+    assert rqs[0].nodes_list == ['roadm Brest_KLA', 'roadm Lannion_CAS', 'roadm Lorient_KMA', 'roadm Vannes_KBE']
+    assert rqs[0].loose_list == ['STRICT', 'LOOSE', 'STRICT', 'STRICT']