diff --git a/examples/path_requests_run.py b/examples/path_requests_run.py
index 83432c1a..43fd8d9f 100755
--- a/examples/path_requests_run.py
+++ b/examples/path_requests_run.py
@@ -62,10 +62,17 @@ def requests_from_json(json_data,equipment):
         params['spacing'] = req['path-constraints']['te-bandwidth']['spacing']
 
         # recover trx physical param (baudrate, ...) from type and mode
+        # in trx_mode_params optical power is read from equipment['SI']['default'] and
+        # nb_channel is computed based on min max frequency and spacing
         trx_params = trx_mode_params(equipment,params['trx_type'],params['trx_mode'],True)
         params.update(trx_params)
-        params['power'] = req['path-constraints']['te-bandwidth']['output-power']
-        params['nb_channel'] = req['path-constraints']['te-bandwidth']['max-nb-of-channel']
+        # optical power might be set differently in the request. if it is indicated then the 
+        # params['power'] is updated
+        if req['path-constraints']['te-bandwidth']['output-power']:
+            params['power'] = req['path-constraints']['te-bandwidth']['output-power']
+        # same process for nb-channel
+        if req['path-constraints']['te-bandwidth']['max-nb-of-channel'] :
+            params['nb_channel'] = req['path-constraints']['te-bandwidth']['max-nb-of-channel']
         requests_list.append(Path_request(**params))
     return requests_list
 
diff --git a/gnpy/core/request.py b/gnpy/core/request.py
index 04222641..580d6759 100644
--- a/gnpy/core/request.py
+++ b/gnpy/core/request.py
@@ -68,7 +68,8 @@ class Path_request:
                             f'baud_rate:\t{self.baud_rate * 1e-9} Gbaud',
                             f'bit_rate:\t{self.bit_rate * 1e-9} Gb/s',
                             f'spacing:\t{self.spacing * 1e-9} GHz',
-                            f'power:  \t{round(lin2db(self.power)+30,2)} dBm'
+                            f'power:  \t{round(lin2db(self.power)+30,2)} dBm',
+                            f'nb channels: \t{self.nb_channel}'
                             '\n'])
 class Disjunction:
     def __init__(self, *args, **params):
@@ -570,6 +571,7 @@ def compute_path_dsjctn(network, equipment, pathreqlist, disjunctions_list):
     for d in disjunctions_list  :
         test_sol = True
         while test_sol:
+            # print('coucou')
             if candidates[d.disjunction_id] :
                 for p in candidates[d.disjunction_id][0]:
                     if allpaths[id(p)].req in pathreqlist_disjt: 
diff --git a/gnpy/core/service_sheet.py b/gnpy/core/service_sheet.py
index 4af835c3..84e2fcbc 100644
--- a/gnpy/core/service_sheet.py
+++ b/gnpy/core/service_sheet.py
@@ -32,7 +32,7 @@ logger = getLogger(__name__)
 # Type for input data
 class Request(namedtuple('Request', 'request_id source destination trx_type mode \
     spacing power nb_channel disjoint_from nodes_list is_loose')):
-    def __new__(cls, request_id, source, destination, trx_type,  mode , spacing , power , nb_channel , disjoint_from ='' ,  nodes_list = None, is_loose = ''):
+    def __new__(cls, request_id, source, destination, trx_type,  mode , spacing , power = None, nb_channel = None , disjoint_from ='' ,  nodes_list = None, is_loose = ''):
         return super().__new__(cls, request_id, source, destination, trx_type, mode, spacing, power, nb_channel, disjoint_from,  nodes_list, is_loose)
 
 # Type for output data:  // from dutc
@@ -73,8 +73,14 @@ class Request_element(Element):
             exit()
         # excel input are in GHz and dBm
         self.spacing = Request.spacing * 1e9
-        self.power =  db2lin(Request.power) * 1e-3
-        self.nb_channel = int(Request.nb_channel)
+        if Request.power :
+            self.power =  db2lin(Request.power) * 1e-3
+        else:
+            self.power = None
+        if Request.nb_channel :
+            self.nb_channel = int(Request.nb_channel)
+        else:
+            self.nb_channel = None
         if not isinstance(Request.disjoint_from,str):
             value = str(int(Request.disjoint_from))
             if value.endswith('.0'):