Feat: add detailed ROADM impairments per roadm-path

Signed-off-by: EstherLerouzic <esther.lerouzic@orange.com>
Change-Id: I09c55dcff53ffb264609654cde0f1d8b9dc7fe9b

gnpy/core/elements.py

@@ -30,9 +30,10 @@ from logging import getLogger
 
 from gnpy.core.utils import lin2db, db2lin, arrange_frequencies, snr_sum, per_label_average, pretty_summary_print, \
     watt2dbm, psd2powerdbm
-from gnpy.core.parameters import RoadmParams, FusedParams, FiberParams, PumpParams, EdfaParams, EdfaOperational
+from gnpy.core.parameters import RoadmParams, FusedParams, FiberParams, PumpParams, EdfaParams, EdfaOperational, \
+    RoadmPath, RoadmImpairment
 from gnpy.core.science_utils import NliSolver, RamanSolver
-from gnpy.core.info import SpectralInformation, ReferenceCarrier
+from gnpy.core.info import SpectralInformation
 from gnpy.core.exceptions import NetworkTopologyError, SpectrumError, ParametersError
 
 
@@ -259,6 +260,17 @@ class Roadm(_Node):
         self.per_degree_pch_psw = self.params.per_degree_pch_psw
         self.ref_pch_in_dbm = {}
         self.ref_carrier = None
+        # Define the nature of from-to internal connection: express-path, drop-path, add-path
+        # roadm_paths contains a list of RoadmPath object for each path crossing the ROADM
+        self.roadm_paths = []
+        # roadm_path_impairments contains a dictionnary of impairments profiles corresponding to type_variety
+        # first listed add, drop an express constitute the default
+        self.roadm_path_impairments = self.params.roadm_path_impairments
+        # per degree definitions, in case some degrees have particular deviations with respect to default.
+        self.per_degree_impairments = {f'{i["from_degree"]}-{i["to_degree"]}': {"from_degree": i["from_degree"],
+                                                                                "to_degree": i["to_degree"],
+                                                                                "impairment_id": i["impairment_id"]}
+                                       for i in self.params.per_degree_impairments}
 
     @property
     def to_json(self):
@@ -289,6 +301,9 @@ class Roadm(_Node):
             to_json['params']['per_degree_psd_out_mWperGHz'] = self.per_degree_pch_psd
         if self.per_degree_pch_psw:
             to_json['params']['per_degree_psd_out_mWperSlotWidth'] = self.per_degree_pch_psw
+        if self.per_degree_impairments:
+            to_json['per_degree_impairments'] = list(self.per_degree_impairments.values())
+
         return to_json
 
     def __repr__(self):
@@ -404,11 +419,68 @@ class Roadm(_Node):
         delta_power = watt2dbm(input_power) - new_target
 
         spectral_info.apply_attenuation_db(delta_power)
-        spectral_info.pmd = sqrt(spectral_info.pmd ** 2 + self.params.pmd ** 2)
+        spectral_info.pmd = sqrt(spectral_info.pmd ** 2
-        spectral_info.pdl = sqrt(spectral_info.pdl ** 2 + self.params.pdl ** 2)
+                                 + self.get_roadm_path(from_degree=from_degree, to_degree=degree).impairment.pmd ** 2)
+        spectral_info.pdl = sqrt(spectral_info.pdl ** 2
+                                 + self.get_roadm_path(from_degree=from_degree, to_degree=degree).impairment.pdl ** 2)
         self.pch_out_dbm = watt2dbm(spectral_info.signal + spectral_info.nli + spectral_info.ase)
         self.propagated_labels = spectral_info.label
 
+    def set_roadm_paths(self, from_degree, to_degree, path_type, impairment_id=None):
+        """set internal path type: express, drop or add with corresponding impairment
+
+        If no impairment id is defined, then use the first profile that matches the path_type in the
+        profile dictionnary.
+        """
+        # initialize impairment with params.pmd, params.cd
+        # if more detailed parameters are available for the Roadm, the use them instead
+        roadm_global_impairment = {'roadm-pmd': self.params.pmd,
+                                   'roadm-pdl': self.params.pdl}
+        if path_type in ['add', 'drop']:
+            # without detailed imparments, we assume that add OSNR contribution is the same as drop contribution
+            # add_drop_osnr_db = - 10log10(1/add_osnr + 1/drop_osnr) with add_osnr = drop_osnr
+            # = add_osnr_db + 10log10(2)
+            roadm_global_impairment['roadm-osnr'] = self.params.add_drop_osnr + lin2db(2)
+        impairment = RoadmImpairment(roadm_global_impairment)
+
+        if impairment_id is None:
+            # get the first item in the type variety that matches the path_type
+            for path_impairment_id, path_impairment in self.roadm_path_impairments.items():
+                if path_impairment.path_type == path_type:
+                    impairment = path_impairment
+                    impairment_id = path_impairment_id
+                    break
+            # at this point, path_type is not part of roadm_path_impairment, impairment and impairment_id are None
+        else:
+            if impairment_id in self.roadm_path_impairments:
+                impairment = self.roadm_path_impairments[impairment_id]
+            else:
+                msg = f'ROADM {self.uid}: impairment profile id {impairment_id} is not defined in library'
+                raise NetworkTopologyError(msg)
+        # print(from_degree, to_degree, path_type)
+        self.roadm_paths.append(RoadmPath(from_degree=from_degree, to_degree=to_degree, path_type=path_type,
+                                          impairment_id=impairment_id, impairment=impairment))
+
+    def get_roadm_path(self, from_degree, to_degree):
+        """Get internal path type impairment"""
+        for roadm_path in self.roadm_paths:
+            if roadm_path.from_degree == from_degree and roadm_path.to_degree == to_degree:
+                return roadm_path
+        msg = f'Could not find from_degree-to_degree {from_degree}-{to_degree} path in ROADM {self.uid}'
+        raise NetworkTopologyError(msg)
+
+    def get_per_degree_impairment_id(self, from_degree, to_degree):
+        """returns the id of the impairment if the degrees are in the per_degree tab"""
+        if f'{from_degree}-{to_degree}' in self.per_degree_impairments.keys():
+            return self.per_degree_impairments[f'{from_degree}-{to_degree}']["impairment_id"]
+        return None
+
+    def get_path_type_per_id(self, impairment_id):
+        """returns the path_type of the impairment if the is is defined"""
+        if impairment_id in self.roadm_path_impairments.keys():
+            return self.roadm_path_impairments[impairment_id].path_type
+        return None
+
     def __call__(self, spectral_info, degree, from_degree):
         self.propagate(spectral_info, degree=degree, from_degree=from_degree)
         return spectral_info

gnpy/core/network.py

@@ -530,6 +530,62 @@ def set_fiber_input_power(network, fiber, equipment, pref_ch_db):
         fiber.ref_pch_in_dbm = pref_ch_db - loss
 
 
+def set_roadm_internal_paths(roadm, network):
+    """Set ROADM path types (express, add, drop)
+
+    Uses implicit guess if no information is set in ROADM
+    """
+    next_oms = [n.uid for n in network.successors(roadm) if not isinstance(n, elements.Transceiver)]
+    previous_oms = [n.uid for n in network.predecessors(roadm) if not isinstance(n, elements.Transceiver)]
+    drop_port = [n.uid for n in network.successors(roadm) if isinstance(n, elements.Transceiver)]
+    add_port = [n.uid for n in network.predecessors(roadm) if isinstance(n, elements.Transceiver)]
+
+    default_express = 'express'
+    default_add = 'add'
+    default_drop = 'drop'
+    # take user defined element impairment id if it exists
+    correct_from_degrees = []
+    correct_add = []
+    correct_to_degrees = []
+    correct_drop = []
+    for from_degree in previous_oms:
+        correct_from_degrees.append(from_degree)
+        for to_degree in next_oms:
+            correct_to_degrees.append(to_degree)
+            impairment_id = roadm.get_per_degree_impairment_id(from_degree, to_degree)
+            roadm.set_roadm_paths(from_degree=from_degree, to_degree=to_degree, path_type=default_express,
+                                  impairment_id=impairment_id)
+        for drop in drop_port:
+            correct_drop.append(drop)
+            impairment_id = roadm.get_per_degree_impairment_id(from_degree, drop)
+            path_type = roadm.get_path_type_per_id(impairment_id)
+            # a degree connected to a transceiver MUST be add or drop
+            # but a degree connected  to something else could be an express, add or drop
+            # (for example case of external shelves)
+            if path_type and path_type != 'drop':
+                msg = f'Roadm {roadm.uid} path_type is defined as {path_type} but it should be drop'
+                raise NetworkTopologyError(msg)
+            roadm.set_roadm_paths(from_degree=from_degree, to_degree=drop, path_type=default_drop,
+                                  impairment_id=impairment_id)
+    for to_degree in next_oms:
+        for add in add_port:
+            correct_add.append(add)
+            impairment_id = roadm.get_per_degree_impairment_id(add, to_degree)
+            path_type = roadm.get_path_type_per_id(impairment_id)
+            if path_type and path_type != 'add':
+                msg = f'Roadm {roadm.uid} path_type is defined as {path_type} but it should be add'
+                raise NetworkTopologyError(msg)
+            roadm.set_roadm_paths(from_degree=add, to_degree=to_degree, path_type=default_add,
+                                  impairment_id=impairment_id)
+    # sanity check: raise an error if per_degree from or to degrees are not in the correct list
+    # raise an error if user defined path_type is not consistent with inferred path_type:
+    for item in roadm.per_degree_impairments.values():
+        if item['from_degree'] not in correct_from_degrees + correct_add or \
+                item['to_degree'] not in correct_to_degrees + correct_drop:
+            msg = f'Roadm {roadm.uid} has wrong from-to degree uid {item["from_degree"]} - {item["to_degree"]}'
+            raise NetworkTopologyError(msg)
+
+
 def add_roadm_booster(network, roadm):
     next_nodes = [n for n in network.successors(roadm)
                   if not (isinstance(n, elements.Transceiver) or isinstance(n, elements.Fused)
@@ -777,6 +833,7 @@ def build_network(network, equipment, pref_ch_db, pref_total_db, set_connector_l
         set_egress_amplifier(network, roadm, equipment, pref_ch_db, pref_total_db, verbose)
     for roadm in roadms:
         set_roadm_input_powers(network, roadm, equipment, pref_ch_db)
+        set_roadm_internal_paths(roadm, network)
     for fiber in [f for f in network.nodes() if isinstance(f, (elements.Fiber, elements.RamanFiber))]:
         set_fiber_input_power(network, fiber, equipment, pref_ch_db)
 

gnpy/core/parameters.py

@@ -113,8 +113,68 @@ class RoadmParams(Parameters):
             self.pmd = kwargs['pmd']
             self.pdl = kwargs['pdl']
             self.restrictions = kwargs['restrictions']
+            self.roadm_path_impairments = self.get_roadm_path_impairments(kwargs['roadm-path-impairments'])
         except KeyError as e:
             raise ParametersError(f'ROADM configurations must include {e}. Configuration: {kwargs}')
+        self.per_degree_impairments = kwargs.get('per_degree_impairments', [])
+
+    def get_roadm_path_impairments(self, path_impairments_list):
+        """Get the ROADM list of profiles for impairments definition
+
+        transform the ietf model into gnpy internal model: add a path-type in the attributes
+        """
+        if not path_impairments_list:
+            return {}
+        authorized_path_types = {
+            'roadm-express-path': 'express',
+            'roadm-add-path': 'add',
+            'roadm-drop-path': 'drop',
+        }
+        roadm_path_impairments = {}
+        for path_impairment in path_impairments_list:
+            index = path_impairment['roadm-path-impairments-id']
+            path_type = next(key for key in path_impairment if key in authorized_path_types.keys())
+            impairment_dict = dict({'path-type': authorized_path_types[path_type]}, **path_impairment[path_type])
+            roadm_path_impairments[index] = RoadmImpairment(impairment_dict)
+        return roadm_path_impairments
+
+
+class RoadmPath:
+    def __init__(self, from_degree, to_degree, path_type, impairment_id=None, impairment=None):
+        """Records roadm internal paths, types and impairment
+
+        path_type must be in "express", "add", "drop"
+        impairment_id must be one of the id detailed in equipement
+        """
+        self.from_degree = from_degree
+        self.to_degree = to_degree
+        self.path_type = path_type
+        self.impairment_id = impairment_id
+        self.impairment = impairment
+
+
+class RoadmImpairment:
+    """Generic definition of impairments for express, add and drop"""
+    def __init__(self, params):
+        """Records roadm internal paths and types"""
+        self.path_type = params.get('path-type')
+        self.pmd = params.get('roadm-pmd')
+        self.cd = params.get('roadm-cd')
+        self.pdl = params.get('roadm-pdl')
+        self.inband_crosstalk = params.get('roadm-inband-crosstalk')
+        self.maxloss = params.get('roadm-maxloss', 0)
+        if params.get('frequency-range') is not None:
+            self.fmin = params.get('frequency-range')['lower-frequency']
+            self.fmax = params.get('frequency-range')['upper-frequency']
+        else:
+            self.fmin, self.fmax = None, None
+        self.osnr = params.get('roadm-osnr', None)
+        self.pmax = params.get('roadm-pmax', None)
+        self.nf = params.get('roadm-noise-figure', None)
+        self.minloss = params.get('minloss', None)
+        self.typloss = params.get('typloss', None)
+        self.pmin = params.get('pmin', None)
+        self.ptyp = params.get('ptyp', None)
 
 
 class FusedParams(Parameters):

gnpy/example-data/eqpt_config.json

@@ -217,7 +217,70 @@
             "restrictions": {
                 "preamp_variety_list": [],
                 "booster_variety_list": []
-            }
+            },
+            "roadm-path-impairments": []
+        }, {
+            "type_variety": "detailed_impairments",
+            "target_pch_out_db": -20,
+            "add_drop_osnr": 38,
+            "pmd": 0,
+            "pdl": 0,
+            "restrictions": {
+                "preamp_variety_list":[],
+                "booster_variety_list":[]
+            },
+            "roadm-path-impairments": [
+                {
+                    "roadm-path-impairments-id": 0,
+                    "roadm-express-path": {
+                        "frequency-range": {
+                            "lower-frequency": 191.3e12,
+                            "upper-frequency": 196.1e12
+                            },
+                        "roadm-pmd": 0,
+                        "roadm-cd": 0,
+                        "roadm-pdl": 0,
+                        "roadm-inband-crosstalk": 0,
+                        "roadm-maxloss": 16.5
+                        }
+                }, {
+                    "roadm-path-impairments-id": 1,
+                    "roadm-add-path": {
+                        "frequency-range": {
+                            "lower-frequency": 191.3e12,
+                            "upper-frequency": 196.1e12
+                        },
+                        "roadm-pmd": 0,
+                        "roadm-cd": 0,
+                        "roadm-pdl": 0,
+                        "roadm-inband-crosstalk": 0,
+                        "roadm-maxloss": 11.5,
+                        "roadm-pmax": 2.5,
+                        "roadm-osnr": 41,
+                        "roadm-noise-figure": 23
+                    }
+                }, {
+                    "roadm-path-impairments-id": 2,
+                    "roadm-drop-path": {
+                        "frequency-range": {
+                            "lower-frequency": 191.3e12,
+                            "upper-frequency": 196.1e12
+                            },
+                        "roadm-pmd": 0,
+                        "roadm-cd": 0,
+                        "roadm-pdl": 0,
+                        "roadm-inband-crosstalk": 0,
+                        "roadm-maxloss": 11.5,
+                        "roadm-minloss": 7.5,
+                        "roadm-typloss": 10,
+                        "roadm-pmin": -13.5,
+                        "roadm-pmax": -9.5,
+                        "roadm-ptyp": -12,
+                        "roadm-osnr": 41,
+                        "roadm-noise-figure": 15
+                    }
+                }
+            ]
         }
     ],
     "SI": [{

gnpy/tools/json_io.py

@@ -102,7 +102,8 @@ class Roadm(_JsonThing):
         'restrictions': {
             'preamp_variety_list': [],
             'booster_variety_list': []
-        }
+        },
+        'roadm-path-impairments': []
     }
 
     def __init__(self, **kwargs):

tests/data/eqpt_config.json

@@ -86,7 +86,69 @@
             "restrictions": {
                 "preamp_variety_list": [],
                 "booster_variety_list": []
-            }
+            },
+            "roadm-path-impairments": []
+        }, {
+            "type_variety": "example_detailed_impairments",
+            "target_pch_out_db": -20,
+            "add_drop_osnr": 35,
+            "pmd": 0,
+            "pdl": 0,
+            "restrictions": {
+                "preamp_variety_list":[],
+                "booster_variety_list":[]
+                            },
+            "roadm-path-impairments": [
+                  {
+                    "roadm-path-impairments-id": 0,
+                    "roadm-express-path": {
+                        "frequency-range": {
+                            "lower-frequency": 191.3e12,
+                            "upper-frequency": 196.1e12
+                            },
+                        "roadm-pmd": 0,
+                        "roadm-cd": 0,
+                        "roadm-pdl": 0,
+                        "roadm-inband-crosstalk": 0,
+                        "roadm-maxloss": 16.5
+                        }
+                }, {
+                    "roadm-path-impairments-id": 1,
+                    "roadm-add-path": {
+                        "frequency-range": {
+                            "lower-frequency": 191.3e12,
+                            "upper-frequency": 196.1e12
+                        },
+                        "roadm-pmd": 0,
+                        "roadm-cd": 0,
+                        "roadm-pdl": 0,
+                        "roadm-inband-crosstalk": 0,
+                        "roadm-maxloss": 11.5,
+                        "roadm-pmax": 2.5,
+                        "roadm-osnr": 41,
+                        "roadm-noise-figure": 23
+                    }
+                }, {
+                    "roadm-path-impairments-id": 2,
+                    "roadm-drop-path": {
+                        "frequency-range": {
+                            "lower-frequency": 191.3e12,
+                            "upper-frequency": 196.1e12
+                            },
+                        "roadm-pmd": 0,
+                        "roadm-cd": 0,
+                        "roadm-pdl": 0,
+                        "roadm-inband-crosstalk": 0,
+                        "roadm-maxloss": 11.5,
+                        "roadm-minloss": 7.5,
+                        "roadm-typloss": 10,
+                        "roadm-pmin": -13.5,
+                        "roadm-pmax": -9.5,
+                        "roadm-ptyp": -12,
+                        "roadm-osnr": 41,
+                        "roadm-noise-figure": 15
+                    }
+                }]
         }, {
             "target_pch_out_db": -20,
             "add_drop_osnr": 38,

tests/invocation/logs_path_request

@@ -2,6 +2,9 @@ INFO     gnpy.tools.cli_examples:cli_examples.py Computing path requests meshTop
 WARNING  gnpy.tools.json_io:json_io.py 
  WARNING missing type_variety attribute in eqpt_config.json[Roadm]
  default value is type_variety = default
+WARNING  gnpy.tools.json_io:json_io.py 
+ WARNING missing roadm-path-impairments attribute in eqpt_config.json[Roadm]
+ default value is roadm-path-impairments = []
 INFO     gnpy.tools.json_io:json_io.py Automatically converting requests from XLS to JSON
 INFO     gnpy.topology.request:request.py 
 	request 0

tests/invocation/logs_path_requests_run_CD_PMD_PDL_missing

@@ -2,6 +2,9 @@ INFO     gnpy.tools.cli_examples:cli_examples.py Computing path requests CORONET
 WARNING  gnpy.tools.json_io:json_io.py 
  WARNING missing type_variety attribute in eqpt_config.json[Roadm]
  default value is type_variety = default
+WARNING  gnpy.tools.json_io:json_io.py 
+ WARNING missing roadm-path-impairments attribute in eqpt_config.json[Roadm]
+ default value is roadm-path-impairments = []
 INFO     gnpy.topology.request:request.py 
 	request 0
 	Computing path from trx Abilene to trx Albany

tests/invocation/logs_power_sweep_example

@@ -1,6 +1,9 @@
 WARNING  gnpy.tools.json_io:json_io.py 
  WARNING missing type_variety attribute in eqpt_config.json[Roadm]
  default value is type_variety = default
+WARNING  gnpy.tools.json_io:json_io.py 
+ WARNING missing roadm-path-impairments attribute in eqpt_config.json[Roadm]
+ default value is roadm-path-impairments = []
 INFO     gnpy.tools.cli_examples:cli_examples.py source = 'brest'
 INFO     gnpy.tools.cli_examples:cli_examples.py destination = 'rennes'
 WARNING  gnpy.core.network:network.py 

tests/invocation/logs_transmission_saturated

@@ -1,6 +1,9 @@
 WARNING  gnpy.tools.json_io:json_io.py 
  WARNING missing type_variety attribute in eqpt_config.json[Roadm]
  default value is type_variety = default
+WARNING  gnpy.tools.json_io:json_io.py 
+ WARNING missing roadm-path-impairments attribute in eqpt_config.json[Roadm]
+ default value is roadm-path-impairments = []
 INFO     gnpy.tools.cli_examples:cli_examples.py source = 'lannion'
 INFO     gnpy.tools.cli_examples:cli_examples.py destination = 'lorient'
 WARNING  gnpy.core.network:network.py 

tests/test_equalization.py

@@ -69,10 +69,12 @@ def test_equalization_combination_degree(delta_pdb_per_channel, degree, equaliza
             "restrictions": {
                 "preamp_variety_list": [],
                 "booster_variety_list": []
-            }
+            },
+            "roadm-path-impairments": []
         }
     }
     roadm = Roadm(**roadm_config)
+    roadm.set_roadm_paths(from_degree='tata', to_degree=degree, path_type='express')
     roadm.ref_pch_in_dbm['tata'] = 0
     roadm.ref_carrier = ReferenceCarrier(baud_rate=32e9, slot_width=50e9)
     frequency = 191e12 + array([0, 50e9, 150e9, 225e9, 275e9])
@@ -231,7 +233,8 @@ def test_low_input_power(target_out, delta_pdb_per_channel, correction):
             "restrictions": {
                 "preamp_variety_list": [],
                 "booster_variety_list": []
-            }
+            },
+            "roadm-path-impairments": []
         },
         "metadata": {
             "location": {
@@ -243,6 +246,7 @@ def test_low_input_power(target_out, delta_pdb_per_channel, correction):
         }
     }
     roadm = Roadm(**roadm_config)
+    roadm.set_roadm_paths(from_degree='tata', to_degree='toto', path_type='express')
     roadm.ref_pch_in_dbm['tata'] = 0
     roadm.ref_carrier = ReferenceCarrier(baud_rate=32e9, slot_width=50e9)
     si = roadm(si, degree='toto', from_degree='tata')
@@ -283,7 +287,8 @@ def test_2low_input_power(target_out, delta_pdb_per_channel, correction):
             "restrictions": {
                 "preamp_variety_list": [],
                 "booster_variety_list": []
-            }
+            },
+            "roadm-path-impairments": []
         },
         "metadata": {
             "location": {
@@ -295,6 +300,7 @@ def test_2low_input_power(target_out, delta_pdb_per_channel, correction):
         }
     }
     roadm = Roadm(**roadm_config)
+    roadm.set_roadm_paths(from_degree='tata', to_degree='toto', path_type='express')
     roadm.ref_pch_in_dbm['tata'] = 0
     roadm.ref_carrier = ReferenceCarrier(baud_rate=32e9, slot_width=50e9)
     si = roadm(si, degree='toto', from_degree='tata')

tests/test_roadm_restrictions.py

@@ -23,8 +23,8 @@ from gnpy.tools.json_io import network_from_json, load_equipment, load_json, Amp
 from gnpy.core.equipment import trx_mode_params
 from gnpy.topology.request import PathRequest, compute_constrained_path, propagate
 from gnpy.core.info import create_input_spectral_information, Carrier
-from gnpy.core.utils import db2lin, dbm2watt
+from gnpy.core.utils import db2lin, dbm2watt, merge_amplifier_restrictions
-from gnpy.core.exceptions import ConfigurationError
+from gnpy.core.exceptions import ConfigurationError, NetworkTopologyError
 
 
 TEST_DIR = Path(__file__).parent
@@ -549,3 +549,141 @@ def test_wrong_restrictions(restrictions, fail):
     else:
         equipment = _equipment_from_json(json_data, EQPT_LIBRARY_NAME)
         assert equipment['Roadm']['example_test'].restrictions == restrictions
+
+
+@pytest.mark.parametrize('roadm, from_degree, to_degree, expected_impairment_id, expected_type', [
+    ('roadm Lannion_CAS', 'trx Lannion_CAS', 'east edfa in Lannion_CAS to Corlay', 1, 'add'),
+    ('roadm Lannion_CAS', 'west edfa in Lannion_CAS to Stbrieuc', 'east edfa in Lannion_CAS to Corlay', 0, 'express'),
+    ('roadm Lannion_CAS', 'west edfa in Lannion_CAS to Stbrieuc', 'trx Lannion_CAS', 2, 'drop'),
+    ('roadm h', 'west edfa in h to g', 'trx h', None, 'drop')
+])
+def test_roadm_impairments(roadm, from_degree, to_degree, expected_impairment_id, expected_type):
+    """Check that impairment id and types are correct
+    """
+    json_data = load_json(NETWORK_FILE_NAME)
+    for el in json_data['elements']:
+        if el['uid'] == 'roadm Lannion_CAS':
+            el['type_variety'] = 'example_detailed_impairments'
+    equipment = load_equipment(EQPT_LIBRARY_NAME)
+    network = network_from_json(json_data, equipment)
+    build_network(network, equipment, 0.0, 20.0)
+    roadm = next(n for n in network.nodes() if n.uid == roadm)
+    assert roadm.get_roadm_path(from_degree, to_degree).path_type == expected_type
+    assert roadm.get_roadm_path(from_degree, to_degree).impairment_id == expected_impairment_id
+
+
+@pytest.mark.parametrize('type_variety, from_degree, to_degree, impairment_id, expected_type', [
+    (None, 'trx Lannion_CAS', 'east edfa in Lannion_CAS to Corlay', 1, 'add'),
+    ('default', 'trx Lannion_CAS', 'east edfa in Lannion_CAS to Corlay', 3, 'add'),
+    (None, 'west edfa in Lannion_CAS to Stbrieuc', 'east edfa in Lannion_CAS to Corlay', None, 'express')
+])
+def test_roadm_per_degree_impairments(type_variety, from_degree, to_degree, impairment_id, expected_type):
+    """Check that impairment type is correct also if per degree impairment is defined
+    """
+    json_data = load_json(EQPT_LIBRARY_NAME)
+    assert 'type_variety' not in json_data['Roadm'][2]
+    json_data['Roadm'][2]['roadm-path-impairments'] = [
+        {
+            "roadm-path-impairments-id": 1,
+            "roadm-add-path": {
+                "roadm-osnr": 41,
+            }
+        }, {
+            "roadm-path-impairments-id": 3,
+            "roadm-add-path": {
+                "roadm-inband-crosstalk": 0,
+                "roadm-osnr": 20,
+                "roadm-noise-figure": 23
+            }
+        }]
+    equipment = _equipment_from_json(json_data, EQPT_LIBRARY_NAME)
+    assert equipment['Roadm']['default'].type_variety == 'default'
+
+    json_data = load_json(NETWORK_FILE_NAME)
+    for el in json_data['elements']:
+        if el['uid'] == 'roadm Lannion_CAS' and type_variety is not None:
+            el['type_variety'] = type_variety
+            el['params'] = {
+                "per_degree_impairments": [
+                    {
+                        "from_degree": from_degree,
+                        "to_degree": to_degree,
+                        "impairment_id": impairment_id
+                    }]
+            }
+    network = network_from_json(json_data, equipment)
+    build_network(network, equipment, 0.0, 20.0)
+    roadm = next(n for n in network.nodes() if n.uid == 'roadm Lannion_CAS')
+    assert roadm.get_roadm_path(from_degree, to_degree).path_type == expected_type
+    assert roadm.get_roadm_path(from_degree, to_degree).impairment_id == impairment_id
+
+
+@pytest.mark.parametrize('from_degree, to_degree, impairment_id, error, message', [
+    ('trx Lannion_CAS', 'east edfa in Lannion_CAS to Corlay', 2, NetworkTopologyError,
+     'Roadm roadm Lannion_CAS path_type is defined as drop but it should be add'),  # wrong path_type
+    ('trx Lannion_CAS', 'east edfa toto', 1, ConfigurationError,
+     'Roadm roadm Lannion_CAS has wrong from-to degree uid trx Lannion_CAS - east edfa toto'),  # wrong degree
+    ('trx Lannion_CAS', 'east edfa in Lannion_CAS to Corlay', 11, NetworkTopologyError,
+     'ROADM roadm Lannion_CAS: impairment profile id 11 is not defined in library')  # wrong impairment_id
+])
+def test_wrong_roadm_per_degree_impairments(from_degree, to_degree, impairment_id, error, message):
+    """Check that wrong per degree definitions are correctly catched
+    """
+    equipment = load_equipment(EQPT_LIBRARY_NAME)
+    json_data = load_json(NETWORK_FILE_NAME)
+    for el in json_data['elements']:
+        if el['uid'] == 'roadm Lannion_CAS':
+            el['type_variety'] = 'example_detailed_impairments'
+            el['params'] = {
+                "per_degree_impairments": [
+                    {
+                        "from_degree": from_degree,
+                        "to_degree": to_degree,
+                        "impairment_id": impairment_id
+                    }]
+            }
+    network = network_from_json(json_data, equipment)
+    with pytest.raises(error, match=message):
+        build_network(network, equipment, 0.0, 20.0)
+
+
+@pytest.mark.parametrize('path_type, type_variety, expected_pmd, expected_pdl, expected_osnr', [
+    ('express', 'default', 5.0e-12, 0.5, None),  # roadm instance parameters pre-empts library
+    ('express', 'example_test', 5.0e-12, 0.5, None),
+    ('express', 'example_detailed_impairments', 0, 0, None),  # detailed parameters pre-empts global instance ones
+    ('add', 'default', 5.0e-12, 0.5, None),
+    ('add', 'example_test', 5.0e-12, 0.5, None),
+    ('add', 'example_detailed_impairments', 0, 0, 41)])
+def test_impairment_initialization(path_type, type_variety, expected_pmd, expected_pdl, expected_osnr):
+    """Check that impairments are correctly initialized, with this order:
+    - use equipment roadm impairments if no impairment are set in the ROADM instance
+    - use roadm global impairment if roadm global impairment are set
+    - use roadm detailed impairment for the corresponding path_type if roadm type_variety has detailed impairments
+    - use roadm per degree impairment if they are defined
+    """
+    equipment = load_equipment(EQPT_LIBRARY_NAME)
+    extra_params = equipment['Roadm'][type_variety].__dict__
+    roadm_config = {
+        "uid": "roadm Lannion_CAS",
+        "params": {
+            "add_drop_osnr": 38,
+            "pmd": 5.0e-12,
+            "pdl": 0.5
+        }
+    }
+    if type_variety != 'default':
+        roadm_config["type_variety"] = type_variety
+    roadm_config['params'] = merge_amplifier_restrictions(roadm_config['params'], extra_params)
+    roadm = Roadm(**roadm_config)
+    roadm.set_roadm_paths(from_degree='tata', to_degree='toto', path_type=path_type)
+    assert roadm.get_roadm_path(from_degree='tata', to_degree='toto').path_type == path_type
+    assert roadm.get_roadm_path(from_degree='tata', to_degree='toto').impairment.pmd == expected_pmd
+    assert roadm.get_roadm_path(from_degree='tata', to_degree='toto').impairment.pdl == expected_pdl
+    if path_type == 'add':
+        # we assume for simplicity that add contribution is the same as drop contribution
+        # add_drop_osnr_db = 10log10(1/add_osnr + 1/drop_osnr)
+        if type_variety in ['default', 'example_test']:
+            assert roadm.get_roadm_path(from_degree='tata',
+                                        to_degree='toto').impairment.osnr == roadm.params.add_drop_osnr + lin2db(2)
+        else:
+            assert roadm.get_roadm_path(from_degree='tata', to_degree='toto').impairment.osnr == expected_osnr