Fix some compilation warnings
[transportpce.git] / pce / src / main / java / org / opendaylight / transportpce / pce / graph / PostAlgoPathValidator.java
index c2832074cbaf8ead9cbd139d0885be340c00a4b8..544fb40d320bd1b6d8c5ebc8e209c33a91548602 100644 (file)
@@ -9,6 +9,7 @@
 package org.opendaylight.transportpce.pce.graph;
 
 import edu.umd.cs.findbugs.annotations.SuppressFBWarnings;
+import java.math.BigDecimal;
 import java.math.RoundingMode;
 import java.util.ArrayList;
 import java.util.Arrays;
@@ -37,10 +38,9 @@ import org.opendaylight.transportpce.pce.networkanalyzer.PceNode;
 import org.opendaylight.transportpce.pce.networkanalyzer.PceResult;
 import org.opendaylight.yang.gen.v1.http.org.opendaylight.transportpce.pce.rev220808.SpectrumAssignment;
 import org.opendaylight.yang.gen.v1.http.org.opendaylight.transportpce.pce.rev220808.SpectrumAssignmentBuilder;
-import org.opendaylight.yang.gen.v1.http.org.openroadm.network.topology.rev211210.TerminationPoint1;
-import org.opendaylight.yang.gen.v1.http.org.openroadm.network.topology.rev211210.networks.network.node.termination.point.XpdrNetworkAttributes;
-import org.opendaylight.yang.gen.v1.http.org.openroadm.network.types.rev211210.OpenroadmLinkType;
-import org.opendaylight.yang.gen.v1.http.org.openroadm.network.types.rev211210.OpenroadmNodeType;
+import org.opendaylight.yang.gen.v1.http.org.openroadm.network.topology.rev230526.TerminationPoint1;
+import org.opendaylight.yang.gen.v1.http.org.openroadm.network.types.rev230526.OpenroadmLinkType;
+import org.opendaylight.yang.gen.v1.http.org.openroadm.network.types.rev230526.OpenroadmNodeType;
 import org.opendaylight.yang.gen.v1.http.org.openroadm.otn.common.types.rev210924.OpucnTribSlotDef;
 import org.opendaylight.yang.gen.v1.urn.ietf.params.xml.ns.yang.ietf.network.rev180226.NodeId;
 import org.opendaylight.yang.gen.v1.urn.ietf.params.xml.ns.yang.ietf.network.topology.rev180226.LinkId;
@@ -66,7 +66,6 @@ public class PostAlgoPathValidator {
     @SuppressFBWarnings(
         value = "SF_SWITCH_FALLTHROUGH",
         justification = "intentional fallthrough")
-
     public PceResult checkPath(GraphPath<String, PceGraphEdge> path, Map<NodeId, PceNode> allPceNodes,
             Map<LinkId, PceLink> allPceLinks, PceResult pceResult, PceConstraints pceHardConstraints,
             String serviceType) {
@@ -76,8 +75,8 @@ public class PostAlgoPathValidator {
             pceResult.setRC(ResponseCodes.RESPONSE_FAILED);
             return pceResult;
         }
-        int spectralWidthSlotNumber = GridConstant.SPECTRAL_WIDTH_SLOT_NUMBER_MAP
-            .getOrDefault(serviceType, GridConstant.NB_SLOTS_100G);
+        int spectralWidthSlotNumber =
+            GridConstant.SPECTRAL_WIDTH_SLOT_NUMBER_MAP.getOrDefault(serviceType, GridConstant.NB_SLOTS_100G);
         SpectrumAssignment spectrumAssignment = null;
         //variable to deal with 1GE (Nb=1) and 10GE (Nb=10) cases
         switch (serviceType) {
@@ -85,8 +84,8 @@ public class PostAlgoPathValidator {
             case StringConstants.SERVICE_TYPE_OTUC3:
             case StringConstants.SERVICE_TYPE_OTUC4:
             case StringConstants.SERVICE_TYPE_400GE:
-                spectralWidthSlotNumber = GridConstant.SPECTRAL_WIDTH_SLOT_NUMBER_MAP
-                    .getOrDefault(serviceType, GridConstant.NB_SLOTS_400G);
+                spectralWidthSlotNumber =
+                    GridConstant.SPECTRAL_WIDTH_SLOT_NUMBER_MAP.getOrDefault(serviceType, GridConstant.NB_SLOTS_400G);
             //fallthrough
             case StringConstants.SERVICE_TYPE_100GE_T:
             case StringConstants.SERVICE_TYPE_OTU4:
@@ -104,8 +103,7 @@ public class PostAlgoPathValidator {
                 } else {
                     LOG.debug("Spectrum assignment fixedgrid mode");
                     pceResult.setResultWavelength(
-                            GridUtils.getWaveLengthIndexFromSpectrumAssigment(spectrumAssignment.getBeginIndex()
-                                .toJava()));
+                        GridUtils.getWaveLengthIndexFromSpectrumAssigment(spectrumAssignment.getBeginIndex().toJava()));
                 }
                 pceResult.setMinFreq(GridUtils.getStartFrequencyFromIndex(spectrumAssignment.getBeginIndex().toJava()));
                 pceResult.setMaxFreq(GridUtils.getStopFrequencyFromIndex(spectrumAssignment.getStopIndex().toJava()));
@@ -133,49 +131,44 @@ public class PostAlgoPathValidator {
                     LOG.info("In PostAlgoPathValidator: Operational mode Catalog not filled, delegate OSNR calculation"
                         + " to GNPy and margin set to 0");
                 }
-
                 // Check if MaxLatency is defined in the hard constraints
-                if ((pceHardConstraints.getMaxLatency() != -1)
-                        && (!checkLatency(pceHardConstraints.getMaxLatency(), path))) {
+                if (pceHardConstraints.getMaxLatency() != -1
+                        && !checkLatency(pceHardConstraints.getMaxLatency(), path)) {
                     pceResult.setRC(ResponseCodes.RESPONSE_FAILED);
                     pceResult.setLocalCause(PceResult.LocalCause.TOO_HIGH_LATENCY);
                     return pceResult;
                 }
-
                 // Check if nodes are included in the hard constraints
                 if (!checkInclude(path, pceHardConstraints)) {
                     pceResult.setRC(ResponseCodes.RESPONSE_FAILED);
                     pceResult.setLocalCause(PceResult.LocalCause.HD_NODE_INCLUDE);
                     return pceResult;
                 }
-
                 // TODO here other post algo validations can be added
                 // more data can be sent to PceGraph module via PceResult structure if required
-
                 pceResult.setRC(ResponseCodes.RESPONSE_OK);
                 pceResult.setLocalCause(PceResult.LocalCause.NONE);
-                break;
+                return pceResult;
             case StringConstants.SERVICE_TYPE_100GE_M:
             case StringConstants.SERVICE_TYPE_10GE:
             case StringConstants.SERVICE_TYPE_1GE:
-                Map<String, Integer> tribSlotNbMap = Map.of(
-                    StringConstants.SERVICE_TYPE_100GE_M, 20,
-                    StringConstants.SERVICE_TYPE_10GE, 8,
-                    StringConstants.SERVICE_TYPE_1GE, 1);
-                int tribSlotNb = tribSlotNbMap.get(serviceType);
+                int tribSlotNb = Map.of(
+                        StringConstants.SERVICE_TYPE_100GE_M, 20,
+                        StringConstants.SERVICE_TYPE_10GE, 8,
+                        StringConstants.SERVICE_TYPE_1GE, 1)
+                    .get(serviceType);
                 pceResult.setRC(ResponseCodes.RESPONSE_FAILED);
                 pceResult.setServiceType(serviceType);
                 Map<String, List<Uint16>> tribSlot = chooseTribSlot(path, allPceNodes, tribSlotNb);
                 Map<String, Uint16> tribPort = chooseTribPort(path, allPceNodes, tribSlot, tribSlotNb);
                 List<OpucnTribSlotDef> resultTribPortTribSlot = getMinMaxTpTs(tribPort, tribSlot);
-
                 if (resultTribPortTribSlot.get(0) != null && resultTribPortTribSlot.get(1) != null) {
                     pceResult.setResultTribPortTribSlot(resultTribPortTribSlot);
                     pceResult.setRC(ResponseCodes.RESPONSE_OK);
                     LOG.info("In PostAlgoPathValidator: found TribPort {} - tribSlot {} - tribSlotNb {}",
                         tribPort, tribSlot, tribSlotNb);
                 }
-                break;
+                return pceResult;
             case StringConstants.SERVICE_TYPE_ODU4:
             case StringConstants.SERVICE_TYPE_ODUC2:
             case StringConstants.SERVICE_TYPE_ODUC3:
@@ -184,20 +177,18 @@ public class PostAlgoPathValidator {
                 pceResult.setRC(ResponseCodes.RESPONSE_OK);
                 pceResult.setServiceType(serviceType);
                 LOG.info("In PostAlgoPathValidator: ODU4/ODUCn path found {}", path);
-                break;
+                return pceResult;
             default:
                 pceResult.setRC(ResponseCodes.RESPONSE_FAILED);
                 LOG.warn("In PostAlgoPathValidator checkPath: unsupported serviceType {} found {}",
                     serviceType, path);
-                break;
+                return pceResult;
         }
-        return pceResult;
     }
 
     // Check the latency
     private boolean checkLatency(Long maxLatency, GraphPath<String, PceGraphEdge> path) {
         double latency = 0;
-
         for (PceGraphEdge edge : path.getEdgeList()) {
             if (edge.link() == null || edge.link().getLatency() == null) {
                 LOG.warn("- In checkLatency: the link {} does not contain latency field",
@@ -218,45 +209,38 @@ public class PostAlgoPathValidator {
         if (listToInclude.isEmpty()) {
             return true;
         }
-
         List<PceGraphEdge> pathEdges = path.getEdgeList();
         LOG.debug(" in checkInclude vertex list: [{}]", path.getVertexList());
-
         List<String> listOfElementsSubNode = new ArrayList<>();
         listOfElementsSubNode.add(pathEdges.get(0).link().getsourceNetworkSupNodeId());
-        listOfElementsSubNode.addAll(listOfElementsBuild(pathEdges, PceConstraints.ResourceType.NODE,
-            pceHardConstraintsInput));
-
+        listOfElementsSubNode.addAll(
+            listOfElementsBuild(pathEdges, PceConstraints.ResourceType.NODE, pceHardConstraintsInput));
         List<String> listOfElementsCLLI = new ArrayList<>();
         listOfElementsCLLI.add(pathEdges.get(0).link().getsourceCLLI());
-        listOfElementsCLLI.addAll(listOfElementsBuild(pathEdges, PceConstraints.ResourceType.CLLI,
-            pceHardConstraintsInput));
-
+        listOfElementsCLLI.addAll(
+            listOfElementsBuild(pathEdges, PceConstraints.ResourceType.CLLI, pceHardConstraintsInput));
         List<String> listOfElementsSRLG = new ArrayList<>();
         // first link is XPONDEROUTPUT, no SRLG for it
         listOfElementsSRLG.add("NONE");
-        listOfElementsSRLG.addAll(listOfElementsBuild(pathEdges, PceConstraints.ResourceType.SRLG,
-            pceHardConstraintsInput));
-
+        listOfElementsSRLG.addAll(
+            listOfElementsBuild(pathEdges, PceConstraints.ResourceType.SRLG, pceHardConstraintsInput));
         // validation: check each type for each element
-        List<String> listNodeToInclude = listToInclude
-                .stream().filter(rp -> PceConstraints.ResourceType.NODE.equals(rp.getType()))
-                .map(ResourcePair::getName).collect(Collectors.toList());
-        List<String> listSrlgToInclude = listToInclude
-                .stream().filter(rp -> PceConstraints.ResourceType.SRLG.equals(rp.getType()))
-                .map(ResourcePair::getName).collect(Collectors.toList());
-        List<String> listClliToInclude = listToInclude
-                .stream().filter(rp -> PceConstraints.ResourceType.CLLI.equals(rp.getType()))
-                .map(ResourcePair::getName).collect(Collectors.toList());
-
-        return listOfElementsSubNode.containsAll(listNodeToInclude)
-                && listOfElementsSRLG.containsAll(listSrlgToInclude)
-                && listOfElementsCLLI.containsAll(listClliToInclude);
+        return listOfElementsSubNode.containsAll(
+                listToInclude
+                    .stream().filter(rp -> PceConstraints.ResourceType.NODE.equals(rp.getType()))
+                    .map(ResourcePair::getName).collect(Collectors.toList()))
+            && listOfElementsSRLG.containsAll(
+                listToInclude
+                    .stream().filter(rp -> PceConstraints.ResourceType.SRLG.equals(rp.getType()))
+                    .map(ResourcePair::getName).collect(Collectors.toList()))
+            && listOfElementsCLLI.containsAll(
+                listToInclude
+                    .stream().filter(rp -> PceConstraints.ResourceType.CLLI.equals(rp.getType()))
+                    .map(ResourcePair::getName).collect(Collectors.toList()));
     }
 
     private List<String> listOfElementsBuild(List<PceGraphEdge> pathEdges, PceConstraints.ResourceType type,
-        PceConstraints pceHardConstraints) {
-
+            PceConstraints pceHardConstraints) {
         List<String> listOfElements = new ArrayList<>();
         for (PceGraphEdge link : pathEdges) {
             switch (type) {
@@ -297,33 +281,34 @@ public class PostAlgoPathValidator {
     }
 
     private Map<String, Uint16> chooseTribPort(GraphPath<String,
-        PceGraphEdge> path, Map<NodeId, PceNode> allPceNodes, Map<String, List<Uint16>> tribSlotMap, int nbSlot) {
+            PceGraphEdge> path, Map<NodeId, PceNode> allPceNodes, Map<String, List<Uint16>> tribSlotMap, int nbSlot) {
         LOG.debug("In choosetribPort: edgeList = {} ", path.getEdgeList());
         Map<String, Uint16> tribPortMap = new HashMap<>();
-
         for (PceGraphEdge edge : path.getEdgeList()) {
-            NodeId linkSrcNode = edge.link().getSourceId();
-            String linkSrcTp = edge.link().getSourceTP().getValue();
-            NodeId linkDestNode = edge.link().getDestId();
-            String linkDestTp = edge.link().getDestTP().getValue();
-            PceNode pceOtnNodeSrc = allPceNodes.get(linkSrcNode);
-            PceNode pceOtnNodeDest = allPceNodes.get(linkDestNode);
-            List<Uint16> srcTpnPool = pceOtnNodeSrc.getAvailableTribPorts().get(linkSrcTp);
-            List<Uint16> destTpnPool = pceOtnNodeDest.getAvailableTribPorts().get(linkDestTp);
+            List<Uint16> srcTpnPool =
+                allPceNodes
+                    .get(edge.link().getSourceId())
+                    .getAvailableTribPorts()
+                    .get(edge.link().getSourceTP().getValue());
+            List<Uint16> destTpnPool =
+                allPceNodes
+                    .get(edge.link().getDestId())
+                    .getAvailableTribPorts()
+                    .get(edge.link().getDestTP().getValue());
             List<Uint16> commonEdgeTpnPool = new ArrayList<>();
             for (Uint16 srcTpn : srcTpnPool) {
                 if (destTpnPool.contains(srcTpn)) {
                     commonEdgeTpnPool.add(srcTpn);
                 }
             }
-
-            if (!commonEdgeTpnPool.isEmpty()) {
-                Integer startTribSlot = tribSlotMap.values().stream().findFirst().get().get(0).toJava();
-                Integer tribPort = (int) Math.ceil((double)startTribSlot / nbSlot);
-                for (Uint16 commonTribPort : commonEdgeTpnPool) {
-                    if (tribPort.equals(commonTribPort.toJava())) {
-                        tribPortMap.put(edge.link().getLinkId().getValue(), commonTribPort);
-                    }
+            if (commonEdgeTpnPool.isEmpty()) {
+                continue;
+            }
+            Integer startTribSlot = tribSlotMap.values().stream().findFirst().orElseThrow().get(0).toJava();
+            Integer tribPort = (int) Math.ceil((double)startTribSlot / nbSlot);
+            for (Uint16 commonTribPort : commonEdgeTpnPool) {
+                if (tribPort.equals(commonTribPort.toJava())) {
+                    tribPortMap.put(edge.link().getLinkId().getValue(), commonTribPort);
                 }
             }
         }
@@ -332,19 +317,20 @@ public class PostAlgoPathValidator {
     }
 
     private Map<String, List<Uint16>> chooseTribSlot(GraphPath<String,
-        PceGraphEdge> path, Map<NodeId, PceNode> allPceNodes, int nbSlot) {
+            PceGraphEdge> path, Map<NodeId, PceNode> allPceNodes, int nbSlot) {
         LOG.debug("In choosetribSlot: edgeList = {} ", path.getEdgeList());
         Map<String, List<Uint16>> tribSlotMap = new HashMap<>();
-
         for (PceGraphEdge edge : path.getEdgeList()) {
-            NodeId linkSrcNode = edge.link().getSourceId();
-            String linkSrcTp = edge.link().getSourceTP().getValue();
-            NodeId linkDestNode = edge.link().getDestId();
-            String linkDestTp = edge.link().getDestTP().getValue();
-            PceNode pceOtnNodeSrc = allPceNodes.get(linkSrcNode);
-            PceNode pceOtnNodeDest = allPceNodes.get(linkDestNode);
-            List<Uint16> srcTsPool = pceOtnNodeSrc.getAvailableTribSlots().get(linkSrcTp);
-            List<Uint16> destTsPool = pceOtnNodeDest.getAvailableTribSlots().get(linkDestTp);
+            List<Uint16> srcTsPool =
+                allPceNodes
+                    .get(edge.link().getSourceId())
+                    .getAvailableTribSlots()
+                    .get(edge.link().getSourceTP().getValue());
+            List<Uint16> destTsPool =
+                allPceNodes
+                    .get(edge.link().getDestId())
+                    .getAvailableTribSlots()
+                    .get(edge.link().getDestTP().getValue());
             List<Uint16> commonEdgeTsPoolList = new ArrayList<>();
             List<Uint16> tribSlotList = new ArrayList<>();
             for (Uint16 integer : srcTsPool) {
@@ -355,8 +341,7 @@ public class PostAlgoPathValidator {
             Collections.sort(commonEdgeTsPoolList);
             List<Uint16> commonGoodStartEdgeTsPoolList = new ArrayList<>();
             for (Uint16 startEdgeTsPool : commonEdgeTsPoolList) {
-                if (Integer.valueOf(1).equals(startEdgeTsPool.toJava() % nbSlot)
-                        || nbSlot == 1) {
+                if (Integer.valueOf(1).equals(startEdgeTsPool.toJava() % nbSlot) || nbSlot == 1) {
                     commonGoodStartEdgeTsPoolList.add(startEdgeTsPool);
                 }
             }
@@ -385,16 +370,23 @@ public class PostAlgoPathValidator {
 
     private List<OpucnTribSlotDef> getMinMaxTpTs(Map<String, Uint16> tribPort, Map<String, List<Uint16>> tribSlot) {
         String tribport = tribPort.values().toArray()[0].toString();
-        @SuppressWarnings("unchecked")
-        List<Uint16> tsList = (List<Uint16>) tribSlot.values().toArray()[0];
-        OpucnTribSlotDef minOpucnTs = OpucnTribSlotDef
-            .getDefaultInstance(String.join(".", tribport, tsList.get(0).toString()));
-        OpucnTribSlotDef maxOpucnTs = OpucnTribSlotDef
-            .getDefaultInstance(String.join(".", tribport, tsList.get(tsList.size() - 1).toString()));
-        List<OpucnTribSlotDef> minmaxTpTsList = new ArrayList<>();
-        minmaxTpTsList.add(minOpucnTs);
-        minmaxTpTsList.add(maxOpucnTs);
-        return minmaxTpTsList;
+        @SuppressWarnings("unchecked") List<Uint16> tsList = (List<Uint16>) tribSlot.values().toArray()[0];
+        return new ArrayList<>(List.of(
+            OpucnTribSlotDef.getDefaultInstance(String.join(".", tribport, tsList.get(0).toString())),
+            OpucnTribSlotDef.getDefaultInstance(String.join(".", tribport, tsList.get(tsList.size() - 1).toString()))));
+    }
+
+    private double checkOSNR(GraphPath<String, PceGraphEdge> path, Map<NodeId, PceNode> allPceNodes,
+            Map<LinkId, PceLink> allPceLinks, String serviceType, String direction, CatalogUtils cu) {
+        switch (direction) {
+            case StringConstants.SERVICE_DIRECTION_AZ:
+                return checkOSNRaz(path, allPceNodes, allPceLinks, serviceType, cu);
+            case StringConstants.SERVICE_DIRECTION_ZA:
+                return checkOSNRza(path, allPceNodes, allPceLinks, serviceType, cu);
+            default:
+                LOG.error("PostAlgoPathValidator.CheckOSNR : unsupported direction {}", direction);
+                return 0.0;
+        }
     }
 
     /**
@@ -404,357 +396,583 @@ public class PostAlgoPathValidator {
      * @param allPceNode                The map of chosen/relevant PceNodes build from topology pruning.
      * @param allPceLinks               The map of PceLinks build corresponding to the whole topology.
      * @param serviceType               The service Type used to extrapolate Operational mode when it is not provided.
-     * @param direction                 The direction used to scan provided path in a direct or reverse way.
      * @param cu                        CatalogUtils instance.
      * @return the calculated margin according to the Transponder performances and path impairments.
      */
-    @SuppressWarnings("deprecation")
-    @edu.umd.cs.findbugs.annotations.SuppressWarnings("DLS_DEAD_LOCAL_STORE")
-    private double checkOSNR(GraphPath<String, PceGraphEdge> path, Map<NodeId, PceNode> allPceNodes,
-        Map<LinkId, PceLink> allPceLinks, String serviceType, String direction, CatalogUtils cu) {
-        double spacing = 50.0;
-        double calcPdl2 = 0;
-        double calcOsnrdB = 0;
-        double calcCd = 0;
-        double calcPmd2 = 0;
-        double calcOnsrLin = 0.0001;
+    private double checkOSNRaz(GraphPath<String, PceGraphEdge> path, Map<NodeId, PceNode> allPceNodes,
+            Map<LinkId, PceLink> allPceLinks, String serviceType, CatalogUtils cu) {
+        Map<String, Double> signal = new HashMap<>(
+            Map.of(
+                "spacing", Double.valueOf(50.0),
+                "calcPdl2", Double.valueOf(0),
+                "calcCd", Double.valueOf(0),
+                "calcPmd2", Double.valueOf(0),
+                "calcOnsrLin", Double.valueOf(0.0001),
+                "pwrIn", Double.valueOf(-60.0),
+                "pwrOut", Double.valueOf(-60.0)));
+        double calcOnsrdB = 0;
         double margin = 0;
-        double pwrIn = -60.0;
-        double pwrOut = -60.0;
-        int pathElement = 0;
-        int increment = 1;
-        int offsetLink = 0;
         boolean transponderPresent = false;
-        if ((StringConstants.SERVICE_DIRECTION_ZA).equals(direction)) {
-            increment = - 1;
-            offsetLink = -1;
-        }
-        CatalogNodeType cnt;
         List<String> vertices = path.getVertexList();
         List<PceGraphEdge> edges = path.getEdgeList();
-        String opMode = "";
         // LOOP that scans the different Nodes/Links of the path and calculates
         // associated degradations
         // using CatalogUtils primitives to retrieve physical parameters and make a
         // first level calculation
-        Map<String, Double> impairments = new HashMap<>();
-        for (int n = 0; n < vertices.size(); n++) {
-            InstanceIdentifier<TerminationPoint1> nwTpIid;
-            PceNode nextNode = null;
-            if ((StringConstants.SERVICE_DIRECTION_AZ).equals(direction)) {
-                pathElement = n ;
-            } else {
-                pathElement = vertices.size() - n - 1;
-            }
+        int bypassDegree = 0;
+        for (int pathElement = 0; pathElement < 2; pathElement++) {
+            bypassDegree = 0;
             PceNode currentNode = allPceNodes.get(new NodeId(vertices.get(pathElement)));
-            if (((pathElement != vertices.size() - 1) && (StringConstants.SERVICE_DIRECTION_AZ).equals(direction))
-                    || ((pathElement != 0) && (StringConstants.SERVICE_DIRECTION_ZA).equals(direction))) {
-                nextNode = allPceNodes.get(new NodeId(vertices.get(pathElement + increment)));
-            }
-            LOG.debug("loop of check OSNR, n = {} Path Element = {}", n, pathElement);
+            PceNode nextNode = allPceNodes.get(new NodeId(vertices.get(pathElement + 1)));
+            LOG.debug("loop of check OSNR direction AZ, Path Element = {}", pathElement);
             switch (currentNode.getORNodeType()) {
                 case XPONDER:
+                    LOG.debug("loop of check OSNR direction AZ: XPDR, Path Element = {}", pathElement);
                     transponderPresent = true;
-                    String nwTpId = "";
-                    if (((pathElement == 0) && (StringConstants.SERVICE_DIRECTION_AZ).equals(direction))
-                            || ((pathElement == (vertices.size() - 1)) && (StringConstants.SERVICE_DIRECTION_ZA)
-                                .equals(direction))) {
-                        //First Xponder of the path TX side
-                        nwTpId = getAppropriatePceLink((pathElement + offsetLink), edges, allPceLinks, direction)
-                            .getSourceTP().getValue();
-                    } else {
-                        // last Xponder of the path (RX side)
-                        nwTpId = getAppropriatePceLink((pathElement - offsetLink - 1), edges, allPceLinks, direction)
-                        .getDestTP().getValue();
-                    }
-                    nwTpIid = InstanceIdentifiers.createNetworkTerminationPoint1IIDBuilder(
-                            vertices.get(pathElement), nwTpId);
-                    LOG.debug("loop of check OSNR : XPDR, n = {} Path Element = {}", n, pathElement);
-                    try {
-                        if (networkTransactionService.read(LogicalDatastoreType.CONFIGURATION, nwTpIid)
-                                .get().isPresent()) {
-                            XpdrNetworkAttributes xna = networkTransactionService
-                                .read(LogicalDatastoreType.CONFIGURATION, nwTpIid)
-                                .get().get().getXpdrNetworkAttributes();
-                            // If the operational mode of the Xponder is not consistent or
-                            // if the operational mode of the Xponder is not declared in the topology
-                            // (Network TP)
-                            if (currentNode.getXponderOperationalMode(xna).contentEquals(StringConstants.UNKNOWN_MODE)
-                                    || currentNode.getXponderOperationalMode(xna) == null
-                                    || currentNode.getXponderOperationalMode(xna).isEmpty()) {
-                                // Operational mode is retrieved from the service Type assuming it is supported
-                                // by the Xponder
-                                opMode = cu.getPceOperationalModeFromServiceType(
-                                    CatalogConstant.CatalogNodeType.TSP, serviceType);
-                            } else {
-                                // Operational mode is found as an attribute of the network TP
-                                opMode = currentNode.getXponderOperationalMode(xna);
-                            }
-                            LOG.debug("Transponder {} corresponding to path Element {} in the path has {} operational "
-                                    + "mode", currentNode.getNodeId().getValue(), pathElement, opMode);
-                        } else {
-                            LOG.error("Issue accessing the XponderNetworkAttributes of {} for Transponder {}"
-                                + " corresponding to path Element {} in the path ",
-                                nwTpId, currentNode.getNodeId().getValue(), pathElement);
-                            opMode = cu.getPceOperationalModeFromServiceType(
-                                CatalogConstant.CatalogNodeType.TSP, serviceType);
-                            LOG.info("Did not succeed finding network TP {} in Configuration Datastore. Retrieve"
-                                + " default Operational Mode {} from serviceType {}", nwTpId, opMode, serviceType);
-                        }
-                    } catch (InterruptedException | ExecutionException e1) {
-                        opMode = cu.getPceOperationalModeFromServiceType(CatalogConstant.CatalogNodeType.TSP,
-                            serviceType);
-                        LOG.info("Did not succeed finding network TP {} in Configuration Datastore. Retrieve"
-                            + " default Operational Mode {} from serviceType {}", nwTpId, opMode, serviceType);
+                    calcXpdrOSNR(cu, signal,
+                        pathElement == 0
+                            // First transponder on the Path (TX side) / Last Xponder of the path (RX side)
+                            ? edges.get(pathElement).link().getSourceTP().getValue()
+                            : edges.get(pathElement - 1).link().getDestTP().getValue(),
+                        serviceType, currentNode, nextNode, vertices.get(pathElement), pathElement);
+                    break;
+                case SRG:
+                    LOG.debug("loop of check OSNR direction AZ: SRG, Path Element = {}", pathElement);
+                    // This is ADD case : First (optical-tunnel) or 2nd (Regular E2E service from
+                    // Xponder to Xponder) node element of the path is the ADD SRG.
+                    if (edges.get(pathElement).link().getlinkType() != OpenroadmLinkType.ADDLINK) {
+                        LOG.error("Error processing Node {} for which output link {} is not an ADDLINK Type",
+                            currentNode.getNodeId(), pathElement);
                     }
-                    // If TSP is the last of the path
-                    if (((pathElement == (vertices.size() - 1))
-                            && (StringConstants.SERVICE_DIRECTION_AZ).equals(direction))
-                            || ((pathElement == 0) && (StringConstants.SERVICE_DIRECTION_ZA).equals(direction))) {
-                        LOG.debug("Loop n = {}, Step5.1, XPDR, tries calculating Margin, just before call", n);
-                        // Check that accumulated degradations are compatible with TSP performances
-                        // According to OpenROADM spec :
-                        // margin = cu.getPceRxTspParameters(opMode, calcCd, Math.sqrt(calcPmd2), Math.sqrt(calcPdl2),
-                        //              getOsnrDbfromOnsrLin(calcOnsrLin));
-                        // Calculation modified for pdl according to calculation in Julia's Tool
-                        margin = cu.getPceRxTspParameters(opMode, calcCd, Math.sqrt(calcPmd2),
-                            (Math.sqrt(calcPdl2)), getOsnrDbfromOnsrLin(calcOnsrLin));
-                        LOG.info("Loop n = {}, XPDR, calcosnrdB= {}", n, getOsnrDbfromOnsrLin(calcOnsrLin));
-                    } else {
-                        // TSP is first element of the path . To correctly evaluate the TX OOB OSNR from
-                        // its operational mode, we need to know the type of ADD/DROP Mux it is
-                        // connected to
-                        String adnMode = "";
-                        // If the operational mode of the ADD/DROP MUX is not consistent or
-                        // if the operational mode of the ADD/DROP MUX is not declared in the topology
-                        // (Network TP)
-                        if (StringConstants.UNKNOWN_MODE.equals(nextNode.getOperationalMode())
-                                || nextNode.getOperationalMode() == null
-                                || nextNode.getOperationalMode().isEmpty()) {
-                            // Operational mode is set by default to standard opMode for ADD SRGs
-                            adnMode = CatalogConstant.MWWRCORE;
-                        } else {
-                            // Operational mode is found in SRG attributes of the Node
-                            adnMode = nextNode.getOperationalMode();
-                        }
-                        LOG.debug("Transponder {} corresponding to path Element {} in the path is connected to SRG "
-                            + "which has {} operational mode", currentNode.getNodeId().getValue(), pathElement,
-                            adnMode);
-                        // Retrieve the Tx ONSR of the Xponder which results from IB and OOB OSNR
-                        // contributions
-                        calcOnsrLin = cu.getPceTxTspParameters(opMode, adnMode);
-                        // Retrieve the spacing associated with Xponder operational mode that is needed
-                        // to calculate OSNR
-                        spacing = cu.getPceTxTspChannelSpacing(opMode);
-                        LOG.info("Transponder {} corresponding to path Element {} in the path has a TX OSNR of {} dB",
-                            currentNode.getNodeId().getValue(), pathElement, getOsnrDbfromOnsrLin(calcOnsrLin));
+                    signal.put("pwrIn", Double.valueOf(0));
+                    calcAddContrib(cu, signal, currentNode, edges.get(pathElement + 1).link());
+                    LOG.debug("loop of check OSNR direction AZ: SRG, pathElement = {} link {} Pout = {}",
+                        pathElement, pathElement + 1, signal.get("pwrOut"));
+                    double calcOnsr = signal.get("calcOnsrLin").doubleValue();
+                    if (calcOnsr == Double.NEGATIVE_INFINITY || calcOnsr == Double.POSITIVE_INFINITY) {
+                        return -1.0;
                     }
+                    // For the ADD, degradation brought by the node are calculated from the MW-WR spec.
+                    // The Degree is not considered. This means we must bypass the add-link (ADD)
+                    // and the next node (Degree) which are not considered in the impairments.
+                    pathElement++;
+                    bypassDegree = 1;
                     break;
+                case DEGREE:
+                default:
+                    LOG.error("PostAlgoPathValidator.CheckOSNR : unsupported resource type in the path chain");
+            }
+        }
+        for (int pathElement = 2 + bypassDegree; pathElement < vertices.size() - 1; pathElement++) {
+            PceNode currentNode = allPceNodes.get(new NodeId(vertices.get(pathElement)));
+            PceNode nextNode = allPceNodes.get(new NodeId(vertices.get(pathElement + 1)));
+            LOG.debug("loop of check OSNR direction AZ: Path Element = {}", pathElement);
+            switch (currentNode.getORNodeType()) {
                 case SRG:
-                    String srgMode = "";
-                    // If the operational mode of the ADD/DROP MUX is not consistent or
-                    // if the operational mode of the ADD/DROP MUX is not declared in the topology
-                    // (Network TP)
-                    if (StringConstants.UNKNOWN_MODE.equals(currentNode.getOperationalMode())
-                            || currentNode.getOperationalMode() == null
-                            || currentNode.getOperationalMode().isEmpty()) {
-                        // Operational mode is set by default to standard opMode for ADD/DROP SRGs
-                        srgMode = CatalogConstant.MWWRCORE;
-                    } else {
-                        // Operational mode is found in SRG attributes of the Node
-                        srgMode = currentNode.getOperationalMode();
+                    LOG.debug("loop of check OSNR direction AZ: SRG, Path Element = {}", pathElement);
+                    // Other case is DROP, for which cnt is unchanged (.DROP)
+                    if (edges.get(pathElement - 1).link().getlinkType() != OpenroadmLinkType.DROPLINK) {
+                        LOG.error("Error processing Node {} for which input link {} is not a DROPLINK Type",
+                            currentNode.getNodeId(), pathElement - 1);
                     }
-                    cnt = CatalogConstant.CatalogNodeType.DROP;
-                    LOG.debug("loop of check OSNR : SRG, n = {} Path Element = {}", n, pathElement);
-                    if ((pathElement <= 1) && (StringConstants.SERVICE_DIRECTION_AZ).equals(direction)
-                            || (pathElement >= vertices.size() - 2)
-                            && (StringConstants.SERVICE_DIRECTION_ZA).equals(direction)) {
-                        // This is ADD case : First (optical-tunnel) or 2nd (Regular E2E service from
-                        // Xponder to Xponder) node element of the path is the ADD SRG.
-                        if (!(getAppropriatePceLink((pathElement + offsetLink), edges, allPceLinks, direction)
-                                .getlinkType() == OpenroadmLinkType.ADDLINK)) {
-                            LOG.error("Error processing Node {} for which output link {} is not an ADDLINK Type",
-                                currentNode.getNodeId().toString(), pathElement + offsetLink);
-                        }
-                        cnt = CatalogConstant.CatalogNodeType.ADD;
-                        pwrIn = 0.0;
-                        pwrOut = cu.getPceRoadmAmpOutputPower(cnt, srgMode,
-                            getAppropriatePceLink((pathElement + 1 + offsetLink * 3), edges, allPceLinks, direction)
-                            .getspanLoss(), spacing,
-                            getAppropriatePceLink((pathElement + 1 + offsetLink * 3), edges, allPceLinks, direction)
-                            .getpowerCorrection());
-                        LOG.debug("loop of check OSNR : SRG, n = {} link {} Pout = {}",
-                            pathElement, pathElement + 1 + offsetLink * 3, pwrOut);
-                    } else {
-                        // Other case is DROP, for which cnt is unchanged (.DROP)
-                        if (!(getAppropriatePceLink((pathElement - 1 - offsetLink), edges, allPceLinks, direction)
-                                .getlinkType() == OpenroadmLinkType.DROPLINK)) {
-                            LOG.error("Error processing Node {} for which input link {} is not a DROPLINK Type",
-                                currentNode.getNodeId().toString(), pathElement - 1 - offsetLink);
-                        }
-                        pwrIn = pwrOut - getAppropriatePceLink((pathElement - offsetLink * 3 - 2), edges, allPceLinks,
-                            direction).getspanLoss();
-                        // Calculate degradation accumulated across incoming Link and add them to
-                        // accumulated impairments
-                        calcCd += getAppropriatePceLink((pathElement - offsetLink * 3 - 2), edges, allPceLinks,
-                            direction).getcd();
-                        LOG.info("loop of check OSNR : SRG, n = {} CD on preceeding link {} = {} ps", pathElement,
-                            pathElement - offsetLink * 3 - 2, getAppropriatePceLink((pathElement - offsetLink * 3 - 2),
-                                edges, allPceLinks, direction).getcd());
-                        calcPmd2 += getAppropriatePceLink((pathElement - offsetLink * 3 - 2), edges, allPceLinks,
-                            direction).getpmd2();
-                        // This also includes Non Linear Contribution from the path
-                        calcOnsrLin += cu.calculateNLonsrContribution(pwrOut, getAppropriatePceLink((pathElement
-                            - offsetLink * 3 - 2), edges, allPceLinks, direction).getLength(), spacing);
-                    }
-                    //calculation of the SRG contribution either for Add and Drop
-                    impairments = cu.getPceRoadmAmpParameters(cnt, srgMode,
-                        pwrIn, calcCd, calcPmd2, calcPdl2, calcOnsrLin, spacing);
-                    calcCd = impairments.get("CD").doubleValue();
-                    calcPmd2 = impairments.get("DGD2").doubleValue();
-                    calcPdl2 = impairments.get("PDL2").doubleValue();
-                    calcOnsrLin = impairments.get("ONSRLIN").doubleValue();
-                    if (calcOnsrLin == Double.NEGATIVE_INFINITY || calcOnsrLin == Double.POSITIVE_INFINITY) {
+                    PceLink pceLink = edges.get(pathElement - 2).link();
+                    LOG.info("loop of check OSNR : SRG, pathElement = {} CD on preceeding link {} = {} ps",
+                        pathElement, pathElement - 2, pceLink.getcd());
+                    calcDropContrib(cu, signal, currentNode, pceLink);
+                    double calcOnsr = signal.get("calcOnsrLin").doubleValue();
+                    if (calcOnsr == Double.NEGATIVE_INFINITY || calcOnsr == Double.POSITIVE_INFINITY) {
                         return -1.0;
                     }
-                    if (pathElement > 1) {
-                        // If SRG is not the first or the second element of the Path, it is the DROP
-                        // side.
-                        // After accumulated degradations are calculated, we also need to calculate
-                        // resulting OSNR in dB to pass it to the method that verifies end Xponder
-                        // performances are compatible with degradations experienced on the path
-                        try {
-                            calcOsnrdB = getOsnrDbfromOnsrLin(calcOnsrLin);
-                            LOG.info("checkOSNR loop, last SRG osnr is {} dB", calcOsnrdB);
-                            LOG.info("Loop n = {}, DROP, calcOsnrdB= {}", n, calcOsnrdB);
-                        } catch (ArithmeticException e) {
-                            LOG.debug("In checkOSNR: OSNR is equal to 0 and the number of links is: {}",
-                                path.getEdgeList().size());
-                            return -1.0;
-                        }
-                    }
-                    if (CatalogConstant.CatalogNodeType.ADD.equals(cnt)) {
-                        // For the ADD, degradation brought by the node are calculated from the MW-WR spec.
-                        // The Degree is not considered. This means we must bypass the add-link (ADD)
-                        // and the next node (Degree) which are not considered in the impairments.
-                        n++;
+                    // If SRG is not the first or the second element of the Path, it is the DROP
+                    // side.
+                    // After accumulated degradations are calculated, we also need to calculate
+                    // resulting OSNR in dB to pass it to the method that verifies end Xponder
+                    // performances are compatible with degradations experienced on the path
+                    try {
+                        calcOnsrdB = getOsnrDbfromOnsrLin(calcOnsr);
+                        LOG.info("checkOSNR loop, last SRG osnr is {} dB", calcOnsrdB);
+                        LOG.info("Loop pathElement = {}, DROP, calcOnsrdB= {}", pathElement, calcOnsrdB);
+                    } catch (ArithmeticException e) {
+                        LOG.debug("In checkOSNR: OSNR is equal to 0 and the number of links is: {}",
+                            path.getEdgeList().size());
+                        return -1.0;
                     }
-                    impairments.clear();
                     break;
                 case DEGREE:
                     if (nextNode.getORNodeType() != OpenroadmNodeType.DEGREE) {
                         //This is the case of DROP, ROADM degree is not considered
                         break;
                     }
-                    LOG.info("loop of check OSNR : DEGREE, n = {} Path Element = {}", n, pathElement);
-                    cnt = CatalogConstant.CatalogNodeType.EXPRESS;
-                    String degree1Mode = "";
-                    String degree2Mode = "";
-                    // If the operational mode of the Degree is not consistent or if the operational
-                    // mode is not declared in the topology
-                    if (StringConstants.UNKNOWN_MODE.equals(currentNode.getOperationalMode())
-                            || currentNode.getOperationalMode() == null
-                            || currentNode.getOperationalMode().isEmpty()) {
-                        // Operational mode is set by default to standard opMode for Degree
-                        degree1Mode = CatalogConstant.MWMWCORE;
-                    } else {
-                        // Operational mode is found in degree-attributes of the Node
-                        degree1Mode = currentNode.getOperationalMode();
+                    LOG.info("loop of check OSNR direction AZ: DEGREE, Path Element = {}", pathElement);
+                    calcBypassContrib(cu, signal, currentNode, nextNode,
+                        edges.get(pathElement - 1).link(), edges.get(pathElement + 1).link());
+                    double calcOnsrLin = signal.get("calcOnsrLin").doubleValue();
+                    LOG.debug(
+                        "Loop pathElement= {}, DEGREE, calcOnsrdB= {}", pathElement, getOsnrDbfromOnsrLin(calcOnsrLin));
+                    if (calcOnsrLin == Double.NEGATIVE_INFINITY || calcOnsrLin == Double.POSITIVE_INFINITY) {
+                        return -1.0;
+                    }
+                    // increment pathElement so that in next step we will not point to Degree2 but
+                    // next node
+                    pathElement++;
+                    LOG.info("Accumulated degradations in the path including ROADM {} + {} are CD: {}; PMD2: "
+                        + "{}; Pdl2 : {}; ONSRdB : {}", currentNode.getNodeId(), nextNode.getNodeId(),
+                        signal.get("calcCd"), signal.get("calcPmd2"), signal.get("calcPdl2"),
+                        getOsnrDbfromOnsrLin(calcOnsrLin));
+                    break;
+                case XPONDER:
+                    LOG.debug("loop of check OSNR direction AZ: XPDR, Path Element = {}", pathElement);
+                    LOG.error("unsupported back to back transponder configuration");
+                    return -1.0;
+                default:
+                    LOG.error("PostAlgoPathValidator.CheckOSNR : unsupported resource type in the path chain");
+            }
+        }
+        PceNode currentNode = allPceNodes.get(new NodeId(vertices.get(vertices.size() - 1)));
+        LOG.debug("loop of check OSNR, Path Element = {}", vertices.size() - 1);
+        switch (currentNode.getORNodeType()) {
+            case XPONDER:
+                LOG.debug("loop of check OSNR direction AZ: XPDR, Path Element = {}", vertices.size() - 1);
+                transponderPresent = true;
+                // TSP is the last of the path
+                margin = getLastXpdrMargin(cu, signal, edges.get(vertices.size() - 2).link().getDestTP().getValue(),
+                    serviceType, currentNode, vertices.get(vertices.size() - 1), vertices.size() - 1);
+                break;
+            case SRG:
+                LOG.debug("loop of check OSNR direction AZ: SRG, Path Element = {}", vertices.size() - 1);
+                // Other case is DROP, for which cnt is unchanged (.DROP)
+                if (edges.get(vertices.size() - 2).link().getlinkType() != OpenroadmLinkType.DROPLINK) {
+                    LOG.error("Error processing Node {} for which input link {} is not a DROPLINK Type",
+                        currentNode.getNodeId(), vertices.size() - 2);
+                }
+                PceLink pceLink = edges.get(vertices.size() - 3).link();
+                LOG.info("loop of check OSNR : SRG, pathElement = {} CD on preceeding link {} = {} ps",
+                    vertices.size() - 1, vertices.size() - 3, pceLink.getcd());
+                calcDropContrib(cu, signal, currentNode, pceLink);
+                double calcOnsr = signal.get("calcOnsrLin").doubleValue();
+                //commented out to avoid spotbug DLS_DEAD_LOCAL_STORE pwrIn = impairments.get("pwrIn");
+                if (calcOnsr == Double.NEGATIVE_INFINITY || calcOnsr == Double.POSITIVE_INFINITY) {
+                    return -1.0;
+                }
+                // If SRG is not the first or the second element of the Path, it is the DROP
+                // side.
+                // After accumulated degradations are calculated, we also need to calculate
+                // resulting OSNR in dB to pass it to the method that verifies end Xponder
+                // performances are compatible with degradations experienced on the path
+                try {
+                    calcOnsrdB = getOsnrDbfromOnsrLin(calcOnsr);
+                    LOG.info("checkOSNR loop, last SRG osnr is {} dB", calcOnsrdB);
+                    LOG.info("Loop pathElement = {}, DROP, calcOnsrdB= {}", vertices.size() - 1, calcOnsrdB);
+                } catch (ArithmeticException e) {
+                    LOG.debug("In checkOSNR: OSNR is equal to 0 and the number of links is: {}",
+                        path.getEdgeList().size());
+                    return -1.0;
+                }
+                break;
+            case DEGREE:
+            default:
+                LOG.error("PostAlgoPathValidator.CheckOSNR : unsupported resource type in the path chain last element");
+        }
+        LOG.info("- In checkOSNR: accumulated CD = {} ps, PMD = {} ps, PDL = {} dB, and resulting OSNR calcOnsrdB = {} "
+            + "dB and ONSR dB exterapolated from calcosnrlin = {} including non linear contributions",
+            signal.get("calcCd"), Math.sqrt(signal.get("calcPmd2").doubleValue()),
+            Math.sqrt(signal.get("calcPdl2").doubleValue()), calcOnsrdB,
+            getOsnrDbfromOnsrLin(signal.get("calcOnsrLin").doubleValue()));
+        if (!transponderPresent) {
+            LOG.info("No transponder in the path, User shall check from CD, PMD, and OSNR values provided "
+                + "that optical tunnel degradations are compatible with external transponder performances");
+            return 0.0;
+        }
+        double delta = margin - SYS_MARGIN;
+        LOG.info("In checkOSNR: Transponder Operational mode results in a residual margin of {} dB, according "
+            + "to CD, PMD and DGD induced penalties and set System Margin of {} dB.",
+            delta, SYS_MARGIN);
+        String validationMessage = delta >= 0 ? "VALIDATED" : "INVALIDATED";
+        LOG.info("- In checkOSNR: A to Z Path from {} to {} {}",
+                vertices.get(0), vertices.get(vertices.size() - 1), validationMessage);
+        return delta;
+    }
+
+    /**
+     * Calculates the OSNR of a path, according to the direction (AtoZ/ZtoA), using the operational-modes Catalog.
+     *
+     * @param path                      the AtoZ path provided by the PCE.
+     * @param allPceNode                The map of chosen/relevant PceNodes build from topology pruning.
+     * @param allPceLinks               The map of PceLinks build corresponding to the whole topology.
+     * @param serviceType               The service Type used to extrapolate Operational mode when it is not provided.
+     * @param cu                        CatalogUtils instance.
+     * @return the calculated margin according to the Transponder performances and path impairments.
+     */
+    private double checkOSNRza(GraphPath<String, PceGraphEdge> path, Map<NodeId, PceNode> allPceNodes,
+            Map<LinkId, PceLink> allPceLinks, String serviceType, CatalogUtils cu) {
+        Map<String, Double> signal = new HashMap<>(
+            Map.of(
+                "spacing", Double.valueOf(50.0),
+                "calcPdl2", Double.valueOf(0),
+                "calcCd", Double.valueOf(0),
+                "calcPmd2", Double.valueOf(0),
+                "calcOnsrLin", Double.valueOf(0.0001),
+                "pwrIn", Double.valueOf(-60.0),
+                "pwrOut", Double.valueOf(-60.0)));
+        double calcOnsrdB = 0;
+        double margin = 0;
+        boolean transponderPresent = false;
+        List<String> vertices = path.getVertexList();
+        List<PceGraphEdge> edges = path.getEdgeList();
+        // LOOP that scans the different Nodes/Links of the path and calculates
+        // associated degradations
+        // using CatalogUtils primitives to retrieve physical parameters and make a
+        // first level calculation
+        int bypassDegree = 0;
+        for (int pathElement = vertices.size() - 1; pathElement > vertices.size() - 3; pathElement--) {
+            bypassDegree = 0;
+            PceNode currentNode = allPceNodes.get(new NodeId(vertices.get(pathElement)));
+            PceNode nextNode = allPceNodes.get(new NodeId(vertices.get(pathElement - 1)));
+            LOG.debug("loop of check OSNR direction ZA:  Path Element = {}", pathElement);
+            switch (currentNode.getORNodeType()) {
+                case XPONDER:
+                    LOG.debug("loop of check OSNR direction ZA: XPDR, Path Element = {}", pathElement);
+                    transponderPresent = true;
+                    calcXpdrOSNR(cu, signal,
+                        pathElement == vertices.size() - 1
+                            // First transponder on the Path (TX side) / Last Xponder of the path (RX side)
+                            ? getOppPceLink(pathElement - 1, edges, allPceLinks).getSourceTP().getValue()
+                            : getOppPceLink((pathElement), edges, allPceLinks).getDestTP().getValue(),
+                        serviceType, currentNode, nextNode, vertices.get(pathElement), pathElement);
+                    break;
+                case SRG:
+                    LOG.debug("loop of check OSNR direction ZA: SRG, Path Element = {}", pathElement);
+                    // This is ADD case : First (optical-tunnel) or 2nd (Regular E2E service from
+                    // Xponder to Xponder) node element of the path is the ADD SRG.
+                    if (getOppPceLink(pathElement - 1, edges, allPceLinks).getlinkType() != OpenroadmLinkType.ADDLINK) {
+                        LOG.error("Error processing Node {} for which output link {} is not an ADDLINK Type",
+                            currentNode.getNodeId(), pathElement - 1);
+                    }
+                    signal.put("pwrIn", Double.valueOf(0));
+                    calcAddContrib(cu, signal, currentNode, getOppPceLink(pathElement - 2, edges, allPceLinks));
+                    double calcOnsr = signal.get("calcOnsrLin").doubleValue();
+                    if (calcOnsr == Double.NEGATIVE_INFINITY || calcOnsr == Double.POSITIVE_INFINITY) {
+                        return -1.0;
                     }
-                    // Same for next node which is the second degree of a ROADM node
-                    if (StringConstants.UNKNOWN_MODE.equals(nextNode.getOperationalMode())
-                            || nextNode.getOperationalMode() == null
-                            || nextNode.getOperationalMode().isEmpty()) {
-                        degree2Mode = CatalogConstant.MWMWCORE;
-                    } else {
-                        degree2Mode = currentNode.getOperationalMode();
+                    // For the ADD, degradation brought by the node are calculated from the MW-WR spec.
+                    // The Degree is not considered. This means we must bypass the add-link (ADD)
+                    // and the next node (Degree) which are not considered in the impairments.
+                    pathElement--;
+                    bypassDegree = 1;
+                    break;
+                case DEGREE:
+                default:
+                    LOG.error("PostAlgoPathValidator.CheckOSNR : unsupported resource type in the path chain");
+            }
+        }
+        for (int pathElement = vertices.size() - 3 - bypassDegree; pathElement > 0; pathElement--) {
+            PceNode currentNode = allPceNodes.get(new NodeId(vertices.get(pathElement)));
+            PceNode nextNode = allPceNodes.get(new NodeId(vertices.get(pathElement - 1)));
+            LOG.debug("loop of check OSNR direction ZA: Path Element = {}", pathElement);
+            switch (currentNode.getORNodeType()) {
+                case SRG:
+                    LOG.debug("loop of check OSNR direction ZA: SRG, Path Element = {}", pathElement);
+                    if (getOppPceLink(pathElement, edges, allPceLinks).getlinkType() != OpenroadmLinkType.DROPLINK) {
+                        LOG.error("Error processing Node {} for which input link {} is not a DROPLINK Type",
+                            currentNode.getNodeId(), pathElement);
+                    }
+                    PceLink pceLink = getOppPceLink(pathElement + 1, edges, allPceLinks);
+                    LOG.info("loop of check OSNR direction ZA: SRG, path Element = {} CD on preceeding link {} = {} ps",
+                        pathElement, pathElement + 1, pceLink.getcd());
+                    calcDropContrib(cu, signal, currentNode, pceLink);
+                    double calcOnsr = signal.get("calcOnsrLin").doubleValue();
+                    if (calcOnsr == Double.NEGATIVE_INFINITY || calcOnsr == Double.POSITIVE_INFINITY) {
+                        return -1.0;
                     }
-                    // At that time OpenROADM provides only one spec for the ROADM nodes
-                    if (!degree1Mode.equals(degree2Mode)) {
-                        LOG.info("Unsupported Hybrid ROADM configuration with Degree1 {} of {} operational mode"
-                            + "and Degree2 {} of {} operational mode. Will by default use operational mode"
-                            + "of Degree2", currentNode.getNodeId().toString(),
-                            degree1Mode, nextNode.getNodeId().toString(), degree2Mode);
+                    // If SRG is not the first or the second element of the Path, it is the DROP
+                    // side.
+                    // After accumulated degradations are calculated, we also need to calculate
+                    // resulting OSNR in dB to pass it to the method that verifies end Xponder
+                    // performances are compatible with degradations experienced on the path
+                    try {
+                        calcOnsrdB = getOsnrDbfromOnsrLin(calcOnsr);
+                        LOG.info("checkOSNR loop, last SRG osnr is {} dB", calcOnsrdB);
+                        LOG.info("Loop Path Element = {}, DROP, calcOnsrdB= {}", pathElement, calcOnsrdB);
+                    } catch (ArithmeticException e) {
+                        LOG.debug("In checkOSNR: OSNR is equal to 0 and the number of links is: {}",
+                            path.getEdgeList().size());
+                        return -1.0;
                     }
-                    pwrIn = pwrOut - getAppropriatePceLink((pathElement - offsetLink - 1), edges, allPceLinks,
-                        direction).getspanLoss();
-                    // Calculate degradation accumulated across incoming Link and add them to
-                    // accumulated impairments
-                    calcCd += getAppropriatePceLink((pathElement - offsetLink - 1), edges, allPceLinks, direction)
-                        .getcd();
-                    calcPmd2 += getAppropriatePceLink((pathElement - offsetLink - 1), edges, allPceLinks, direction)
-                        .getpmd2();
-                    // This also includes Non Linear Contribution from the path
-                    calcOnsrLin += cu.calculateNLonsrContribution(pwrOut, getAppropriatePceLink((pathElement
-                        - offsetLink - 1), edges, allPceLinks, direction).getLength(), spacing);
-                    // Calculate output power for next span (Output of degree 2)
-                    pwrOut = cu.getPceRoadmAmpOutputPower(cnt, degree2Mode, getAppropriatePceLink((pathElement
-                        + 3 * offsetLink + 1), edges, allPceLinks, direction).getspanLoss(), spacing,
-                        getAppropriatePceLink((pathElement + 3 * offsetLink + 1), edges, allPceLinks, direction)
-                        .getpowerCorrection());
-                    // Adds to accumulated impairments the degradation associated with the Express
-                    // path of ROADM : Degree1, express link, Degree2
-                    impairments = cu.getPceRoadmAmpParameters(cnt, degree2Mode,
-                        pwrIn, calcCd, calcPmd2, calcPdl2, calcOnsrLin, spacing);
-                    calcCd = impairments.get("CD").doubleValue();
-                    calcPmd2 = impairments.get("DGD2").doubleValue();
-                    calcPdl2 = impairments.get("PDL2").doubleValue();
-                    calcOnsrLin = impairments.get("ONSRLIN").doubleValue();
-                    LOG.debug("Loop n = {}, DEGREE, calcOsnrdB= {}", n, getOsnrDbfromOnsrLin(calcOnsrLin));
+                    break;
+                case DEGREE:
+                    if (nextNode.getORNodeType() != OpenroadmNodeType.DEGREE) {
+                        //This is the case of DROP, ROADM degree is not considered
+                        break;
+                    }
+                    LOG.info("loop of check OSNR direction ZA: DEGREE, Path Element = {}", pathElement);
+                    calcBypassContrib(cu, signal, currentNode, nextNode,
+                        getOppPceLink(pathElement, edges, allPceLinks),
+                        getOppPceLink(pathElement - 2, edges, allPceLinks));
+                    double calcOnsrLin = signal.get("calcOnsrLin").doubleValue();
+                    LOG.debug("Loop Path Element = {}, DEGREE, calcOnsrdB= {}",
+                            pathElement, getOsnrDbfromOnsrLin(calcOnsrLin));
                     if (calcOnsrLin == Double.NEGATIVE_INFINITY || calcOnsrLin == Double.POSITIVE_INFINITY) {
                         return -1.0;
                     }
                     // increment pathElement so that in next step we will not point to Degree2 but
                     // next node
-                    n++;
+                    pathElement--;
                     LOG.info("Accumulated degradations in the path including ROADM {} + {} are CD: {}; PMD2: "
-                        + "{}; Pdl2 : {}; ONSRdB : {}", currentNode.getNodeId().toString(),
-                        nextNode.getNodeId().toString(), calcCd, calcPmd2, calcPdl2, getOsnrDbfromOnsrLin(calcOnsrLin));
+                        + "{}; Pdl2 : {}; ONSRdB : {}", currentNode.getNodeId(), nextNode.getNodeId(),
+                        signal.get("calcCd"), signal.get("calcPmd2"), signal.get("calcPdl2"),
+                        getOsnrDbfromOnsrLin(calcOnsrLin));
                     break;
+                case XPONDER:
+                    LOG.debug("loop of check OSNR direction AZ: XPDR, Path Element = {}", pathElement);
+                    LOG.error("unsupported back to back transponder configuration");
+                    return -1.0;
                 default:
                     LOG.error("PostAlgoPathValidator.CheckOSNR : unsupported resource type in the path chain");
             }
         }
-        LOG.info("- In checkOSNR: accumulated CD = {} ps, PMD = {} ps, PDL = {} dB, and resulting OSNR calcOsnrdB = {} "
-            + "dB and ONSR dB exterapolated from calcosnrlin = {}"
-            + " including non linear contributions",
-            calcCd, Math.sqrt(calcPmd2), Math.sqrt(calcPdl2), calcOsnrdB, getOsnrDbfromOnsrLin(calcOnsrLin));
+        PceNode currentNode = allPceNodes.get(new NodeId(vertices.get(0)));
+        LOG.debug("loop of check OSNR direction ZA: Path Element = 0");
+        switch (currentNode.getORNodeType()) {
+            case XPONDER:
+                LOG.debug("loop of check OSNR direction ZA: XPDR, Path Element = 0");
+                transponderPresent = true;
+                // TSP is the last of the path
+                margin = getLastXpdrMargin(cu, signal, getOppPceLink(0, edges, allPceLinks).getDestTP().getValue(),
+                    serviceType, currentNode, vertices.get(0), 0);
+                break;
+            case SRG:
+                LOG.debug("loop of check OSNR direction ZA: SRG, Path Element = 0");
+                if (getOppPceLink(0, edges, allPceLinks).getlinkType() != OpenroadmLinkType.DROPLINK) {
+                    LOG.error("Error processing Node {} for which input link 0 is not a DROPLINK Type",
+                        currentNode.getNodeId());
+                }
+                PceLink pceLink = getOppPceLink(1, edges, allPceLinks);
+                LOG.info("loop of check OSNR direction ZA: SRG, path Element = 0 CD on preceeding link 1 = {} ps",
+                    pceLink.getcd());
+                calcDropContrib(cu, signal, currentNode, pceLink);
+                double calcOnsr = signal.get("calcOnsrLin").doubleValue();
+                //commented out to avoid spotbug DLS_DEAD_LOCAL_STORE pwrIn = impairments.get("pwrIn");
+                if (calcOnsr == Double.NEGATIVE_INFINITY || calcOnsr == Double.POSITIVE_INFINITY) {
+                    return -1.0;
+                }
+                // If SRG is not the first or the second element of the Path, it is the DROP
+                // side.
+                // After accumulated degradations are calculated, we also need to calculate
+                // resulting OSNR in dB to pass it to the method that verifies end Xponder
+                // performances are compatible with degradations experienced on the path
+                try {
+                    calcOnsrdB = getOsnrDbfromOnsrLin(calcOnsr);
+                    LOG.info("checkOSNR loop, last SRG osnr is {} dB", calcOnsrdB);
+                    LOG.info("Loop Path Element = 0, DROP, calcOnsrdB= {}", calcOnsrdB);
+                } catch (ArithmeticException e) {
+                    LOG.debug("In checkOSNR: OSNR is equal to 0 and the number of links is: {}",
+                        path.getEdgeList().size());
+                    return -1.0;
+                }
+                break;
+            case DEGREE:
+            default:
+                LOG.error("PostAlgoPathValidator.CheckOSNR : unsupported resource type in the path chain last element");
+        }
+        LOG.info("- In checkOSNR: accumulated CD = {} ps, PMD = {} ps, PDL = {} dB, and resulting OSNR calcOnsrdB = {} "
+            + "dB and ONSR dB exterapolated from calcosnrlin = {} including non linear contributions",
+            signal.get("calcCd"), Math.sqrt(signal.get("calcPmd2").doubleValue()),
+            Math.sqrt(signal.get("calcPdl2").doubleValue()), calcOnsrdB,
+            getOsnrDbfromOnsrLin(signal.get("calcOnsrLin").doubleValue()));
         if (!transponderPresent) {
             LOG.info("No transponder in the path, User shall check from CD, PMD, and OSNR values provided "
                 + "that optical tunnel degradations are compatible with external transponder performances");
             return 0.0;
         }
-        LOG.info("In checkOSNR: Transponder Operational mode {} results in a residual margin of {} dB, according "
+        double delta = margin - SYS_MARGIN;
+        LOG.info("In checkOSNR: Transponder Operational mode results in a residual margin of {} dB, according "
             + "to CD, PMD and DGD induced penalties and set System Margin of {} dB.",
-            opMode, margin - SYS_MARGIN, SYS_MARGIN);
-        String validationMessage = "INVALIDATED";
-        if ((margin - SYS_MARGIN) >= 0) {
-            validationMessage = "VALIDATED";
-        }
-        if ((StringConstants.SERVICE_DIRECTION_AZ).equals(direction)) {
-            LOG.info("- In checkOSNR: A to Z Path from {} to {} {}", vertices.get(0),
-                vertices.get(vertices.size() - 1), validationMessage);
-        } else {
-            LOG.info("- In checkOSNR: Z to A Path from {} to {} {}", vertices.get(vertices.size() - 1),
-                vertices.get(0), validationMessage);
+            delta, SYS_MARGIN);
+        String validationMessage = delta >= 0 ? "VALIDATED" : "INVALIDATED";
+        LOG.info("- In checkOSNR: Z to A Path from {} to {} {}",
+                vertices.get(vertices.size() - 1), vertices.get(0), validationMessage);
+        return delta;
+    }
+
+    private String setOpMode(String opMode, String defaultMode) {
+        return
+            opMode == null || opMode.isEmpty() || opMode.contentEquals(StringConstants.UNKNOWN_MODE)
+                ? defaultMode
+                : opMode;
+    }
+
+    private PceLink getOppPceLink(Integer pathEltNber, List<PceGraphEdge> edges,
+            Map<LinkId, PceLink> allPceLinks) {
+        return allPceLinks.get(new LinkId(edges.get(pathEltNber).link().getOppositeLink()));
+    }
+
+    private String getXpdrOpMode(String nwTpId, String vertice, int pathElement, PceNode currentNode,
+            String serviceType, CatalogUtils cu) {
+        InstanceIdentifier<TerminationPoint1> nwTpIid =
+            InstanceIdentifiers.createNetworkTerminationPoint1IIDBuilder(vertice, nwTpId);
+        String opMode = cu.getPceOperationalModeFromServiceType(CatalogConstant.CatalogNodeType.TSP, serviceType);
+        try {
+            if (networkTransactionService.read(LogicalDatastoreType.CONFIGURATION, nwTpIid).get().isPresent()) {
+                // If the operational mode of the Xponder is not consistent nor declared in the topology (Network TP)
+                opMode = setOpMode(
+                    currentNode.getXponderOperationalMode(
+                        networkTransactionService
+                                .read(LogicalDatastoreType.CONFIGURATION, nwTpIid)
+                                .get().orElseThrow().getXpdrNetworkAttributes()),
+                    // Operational mode is found as an attribute of the network TP
+                    opMode);
+                    // Operational mode is retrieved from the service Type assuming it is supported
+                    // by the Xponder
+                LOG.debug(
+                    "Transponder {} corresponding to path Element {} in the path has {} operational mode",
+                    currentNode.getNodeId().getValue(), pathElement, opMode);
+                return opMode;
+            }
+        } catch (InterruptedException | ExecutionException e1) {
+            LOG.error("Issue accessing the XponderNetworkAttributes of {} for Transponder {}"
+                + " corresponding to path Element {} in the path ",
+                nwTpId, currentNode.getNodeId().getValue(), pathElement);
         }
-        return (margin - SYS_MARGIN);
+        LOG.info("Did not succeed finding network TP {} in Configuration Datastore. Retrieve"
+            + " default Operational Mode {} from serviceType {}", nwTpId, opMode, serviceType);
+        return opMode;
     }
 
-    // Method to provide either regular link (AtoZ) or Opposite link (ZtoA) in the list of PceGraphEdges
-    private PceLink getAppropriatePceLink(Integer pathEltNber, List<PceGraphEdge> edges,
-            Map<LinkId, PceLink> allPceLinks, String direction) {
-        if ((StringConstants.SERVICE_DIRECTION_AZ).equals(direction)) {
-            // Returns regular link.
-            return edges.get(pathEltNber).link();
+    private double getLastXpdrMargin(
+            CatalogUtils cu, Map<String, Double> signal,
+            String nwTpId, String serviceType, PceNode currentNode, String vertice, int pathElement) {
+        LOG.debug("Loop Path Element = {}, Step5.1, XPDR, tries calculating Margin, just before call", pathElement);
+        // Check that accumulated degradations are compatible with TSP performances
+        // According to OpenROADM spec :
+        // margin = cu.getPceRxTspParameters(opMode, calcCd, Math.sqrt(calcPmd2), Math.sqrt(calcPdl2),
+        //              getOsnrDbfromOnsrLin(calcOnsrLin));
+        // Calculation modified for pdl according to calculation in Julia's Tool
+        double calcOnsrdB = getOsnrDbfromOnsrLin(signal.get("calcOnsrLin").doubleValue());
+        LOG.info("Loop Path Element = {}, XPDR, calcosnrdB= {}", pathElement, calcOnsrdB);
+        return cu.getPceRxTspParameters(
+            getXpdrOpMode(nwTpId, vertice, pathElement, currentNode, serviceType, cu),
+            signal.get("calcCd").doubleValue(),
+            Math.sqrt(signal.get("calcPmd2").doubleValue()),
+            Math.sqrt(signal.get("calcPdl2").doubleValue()),
+            calcOnsrdB);
+    }
+
+    private void calcXpdrOSNR(
+            CatalogUtils cu, Map<String, Double> signal, String nwTpId, String serviceType,
+            PceNode currentNode, PceNode nextNode, String vertice, int pathElement) {
+        // If the Xponder operational mode (setOpMode Arg1) is not consistent nor declared in the topology (Network TP)
+        // Operational mode is retrieved from the service Type assuming it is supported by the Xponder (setOpMode Arg2)
+        String opMode = getXpdrOpMode(nwTpId, vertice, pathElement, currentNode, serviceType, cu);
+        // If the operational mode of the ADD/DROP MUX is not consistent nor declared in the topology (Network TP)
+        // Operational mode is set by default to standard opMode for ADD SRGs
+        String adnMode = setOpMode(nextNode.getOperationalMode(), CatalogConstant.MWWRCORE);
+        double calcOnsrLin = cu.getPceTxTspParameters(opMode, adnMode);
+        LOG.debug(
+            "Transponder {} corresponding to path Element {} is connected to SRG which has {} operational mode",
+            currentNode.getNodeId().getValue(), pathElement, adnMode);
+        LOG.info("Transponder {} corresponding to path Element {} in the path has a TX OSNR of {} dB",
+            currentNode.getNodeId().getValue(), pathElement, getOsnrDbfromOnsrLin(calcOnsrLin));
+        // Return the Tx ONSR of the Xponder which results from IB and OOB OSNR contributions
+        // and the spacing associated with Xponder operational mode that is needed to calculate OSNR
+        signal.put("spacing", Double.valueOf(cu.getPceTxTspChannelSpacing(opMode)));
+        signal.put("calcOnsrLin", Double.valueOf(calcOnsrLin));
+    }
+
+    private void calcDropContrib(
+            CatalogUtils cu, Map<String, Double> signal, PceNode currentNode, PceLink pceLink) {
+        //calculation of the SRG contribution for Drop
+        calcLineDegradation(cu, signal, pceLink);
+        Map<String, Double> impairments = cu.getPceRoadmAmpParameters(
+            CatalogConstant.CatalogNodeType.DROP,
+            setOpMode(currentNode.getOperationalMode(), CatalogConstant.MWWRCORE),
+        // If the operational mode of the ADD/DROP MUX is not consistent or not declared in the topology (Network TP)
+        // Operational mode is set by default to standard opMode for ADD/DROP SRGs
+            signal.get("pwrIn").doubleValue(),
+            signal.get("calcCd").doubleValue(),
+            signal.get("calcPmd2").doubleValue(),
+            signal.get("calcPdl2").doubleValue(),
+            signal.get("calcOnsrLin").doubleValue(),
+            signal.get("spacing").doubleValue());
+        signal.putAll(
+            Map.of(
+                "calcCd", impairments.get("CD"),
+                "calcPmd2", impairments.get("DGD2"),
+                "calcPdl2", impairments.get("PDL2"),
+                "calcOnsrLin", impairments.get("ONSRLIN")));
+    }
+
+    private void calcAddContrib(
+            CatalogUtils cu, Map<String, Double> signal, PceNode currentNode, PceLink pceLink) {
+        //calculation of the SRG contribution for Add
+        String srgMode = setOpMode(currentNode.getOperationalMode(), CatalogConstant.MWWRCORE);
+        // If the operational mode of the ADD/DROP MUX is not consistent or is not declared in the topology (Network TP)
+        // Operational mode is set by default to standard opMode for ADD/DROP SRGs
+        CatalogNodeType cnt = CatalogConstant.CatalogNodeType.ADD;
+        double pwrOut = cu.getPceRoadmAmpOutputPower(
+                cnt, srgMode, pceLink.getspanLoss(), signal.get("spacing").doubleValue(), pceLink.getpowerCorrection());
+        //calculation of the SRG contribution either for Add and Drop
+        Map<String, Double> impairments = cu.getPceRoadmAmpParameters(cnt, srgMode, 0,
+            signal.get("calcCd").doubleValue(), signal.get("calcPmd2").doubleValue(),
+            signal.get("calcPdl2").doubleValue(),
+            signal.get("calcOnsrLin").doubleValue(), signal.get("spacing").doubleValue());
+        signal.putAll(
+            Map.of(
+                "calcCd", impairments.get("CD"),
+                "calcPmd2", impairments.get("DGD2"),
+                "calcPdl2", impairments.get("PDL2"),
+                "calcOnsrLin", impairments.get("ONSRLIN"),
+                "pwrOut", Double.valueOf(pwrOut)));
+    }
+
+    private void calcBypassContrib(CatalogUtils cu, Map<String, Double> signal,
+            PceNode currentNode, PceNode nextNode, PceLink pceLink0, PceLink pceLink1) {
+        // If the operational mode of the Degree is not consistent or declared in the topology
+        // Operational mode is set by default to standard opMode for Degree
+        String degree1Mode = setOpMode(currentNode.getOperationalMode(), CatalogConstant.MWMWCORE);
+        // Same for next node which is the second degree of a ROADM node
+        String degree2Mode = setOpMode(nextNode.getOperationalMode(), CatalogConstant.MWMWCORE);
+        // At that time OpenROADM provides only one spec for the ROADM nodes
+        if (!degree1Mode.equals(degree2Mode)) {
+            LOG.warn("Unsupported Hybrid ROADM configuration with Degree1 {} of {} operational mode and Degree2 "
+                + "{} of {} operational mode. Will by default use operational mode of Degree2",
+                currentNode.getNodeId(), degree1Mode, nextNode.getNodeId(), degree2Mode);
         }
-            //For Z to A direction, must return the opposite link
-        return allPceLinks.get(new LinkId(edges.get(pathEltNber).link()
-            .getOppositeLink()));
+        calcLineDegradation(cu, signal, pceLink0);
+        CatalogNodeType cnt = CatalogConstant.CatalogNodeType.EXPRESS;
+        double pwrOut = cu.getPceRoadmAmpOutputPower(cnt, degree2Mode, pceLink1.getspanLoss(),
+            signal.get("spacing").doubleValue(), pceLink1.getpowerCorrection());
+        // Adds to accumulated impairments the degradation associated with the Express
+        // path of ROADM : Degree1, express link, Degree2
+        Map<String, Double> impairments = cu.getPceRoadmAmpParameters(cnt, degree2Mode,
+            signal.get("pwrIn").doubleValue(), signal.get("calcCd").doubleValue(),
+            signal.get("calcPmd2").doubleValue(), signal.get("calcPdl2").doubleValue(),
+            signal.get("calcOnsrLin").doubleValue(), signal.get("spacing").doubleValue());
+        signal.putAll(
+            Map.of(
+                "calcCd", impairments.get("CD"),
+                "calcPmd2", impairments.get("DGD2"),
+                "calcPdl2", impairments.get("PDL2"),
+                "calcOnsrLin", impairments.get("ONSRLIN"),
+                "pwrOut", Double.valueOf(pwrOut)));
+    }
+    //TODO these methods might be more indicated in a catalog utils refactoring
+
+    private void calcLineDegradation(CatalogUtils cu, Map<String, Double> signal, PceLink pceLink) {
+        // Calculate degradation accumulated across incoming Link and add them to
+        // accumulated impairments
+        // This also includes Non Linear Contribution from the path
+        signal.putAll(Map.of(
+            "pwrIn", Double.valueOf(signal.get("pwrOut").doubleValue() - pceLink.getspanLoss()),
+            "calcCd", Double.valueOf(signal.get("calcCd").doubleValue() + pceLink.getcd()),
+            "calcPmd2", Double.valueOf(signal.get("calcPmd2").doubleValue() + pceLink.getpmd2()),
+            "calcOnsrLin", Double.valueOf(
+                signal.get("calcOnsrLin").doubleValue()
+                + cu.calculateNLonsrContribution(
+                    signal.get("pwrOut").doubleValue(), pceLink.getLength(), signal.get("spacing").doubleValue()))));
     }
 
-    private double getOsnrDbfromOnsrLin(double onsrLu) {
-        return (10 * Math.log10(1 / onsrLu));
+    private double getOsnrDbfromOnsrLin(double osnrLu) {
+        return 10 * Math.log10(1 / osnrLu);
     }
 
     /**
@@ -774,28 +992,29 @@ public class PostAlgoPathValidator {
         BitSet result = BitSet.valueOf(freqMap);
         boolean isFlexGrid = true;
         LOG.debug("Processing path {} with length {}", path, path.getLength());
-        BitSet pceNodeFreqMap;
         for (PceGraphEdge edge : path.getEdgeList()) {
-            LOG.debug("Processing source {} ", edge.link().getSourceId());
-            if (allPceNodes.containsKey(edge.link().getSourceId())) {
-                PceNode pceNode = allPceNodes.get(edge.link().getSourceId());
+            NodeId srcNodeId = edge.link().getSourceId();
+            LOG.debug("Processing source {} ", srcNodeId);
+            if (allPceNodes.containsKey(srcNodeId)) {
+                PceNode pceNode = allPceNodes.get(srcNodeId);
                 LOG.debug("Processing PCE node {}", pceNode);
-                if (StringConstants.OPENROADM_DEVICE_VERSION_1_2_1.equals(pceNode.getVersion())) {
+                String pceNodeVersion = pceNode.getVersion();
+                NodeId pceNodeId = pceNode.getNodeId();
+                BigDecimal sltWdthGran = pceNode.getSlotWidthGranularity();
+                BigDecimal ctralFreqGran = pceNode.getCentralFreqGranularity();
+                if (StringConstants.OPENROADM_DEVICE_VERSION_1_2_1.equals(pceNodeVersion)) {
                     LOG.debug("Node {}: version is {} and slot width granularity is {} -> fixed grid mode",
-                        pceNode.getNodeId(), pceNode.getVersion(), pceNode.getSlotWidthGranularity());
+                        pceNodeId, pceNodeVersion, sltWdthGran);
                     isFlexGrid = false;
                 }
-                if ((pceNode.getSlotWidthGranularity().setScale(0, RoundingMode.CEILING)
-                        .equals(GridConstant.SLOT_WIDTH_50))
-                        && (pceNode.getCentralFreqGranularity().setScale(0, RoundingMode.CEILING)
-                        .equals(GridConstant.SLOT_WIDTH_50))) {
-                    LOG.debug("Node {}: version is {} with slot width granularity  {} and central "
+                if (sltWdthGran.setScale(0, RoundingMode.CEILING).equals(GridConstant.SLOT_WIDTH_50)
+                        && ctralFreqGran.setScale(0, RoundingMode.CEILING).equals(GridConstant.SLOT_WIDTH_50)) {
+                    LOG.debug("Node {}: version is {} with slot width granularity {} and central "
                             + "frequency granularity is {} -> fixed grid mode",
-                        pceNode.getNodeId(), pceNode.getVersion(), pceNode.getSlotWidthGranularity(),
-                        pceNode.getCentralFreqGranularity());
+                        pceNodeId, pceNodeVersion, sltWdthGran, ctralFreqGran);
                     isFlexGrid = false;
                 }
-                pceNodeFreqMap = pceNode.getBitSetData();
+                BitSet pceNodeFreqMap = pceNode.getBitSetData();
                 LOG.debug("Pce node bitset {}", pceNodeFreqMap);
                 if (pceNodeFreqMap != null) {
                     result.and(pceNodeFreqMap);
@@ -816,19 +1035,19 @@ public class PostAlgoPathValidator {
      * @return a spectrum assignment object which contains begin and stop index. If
      *         no spectrum assignment found, beginIndex = stopIndex = 0
      */
-    private SpectrumAssignment computeBestSpectrumAssignment(BitSet spectrumOccupation, int spectralWidthSlotNumber,
-            boolean isFlexGrid) {
+    private SpectrumAssignment computeBestSpectrumAssignment(
+            BitSet spectrumOccupation, int spectralWidthSlotNumber, boolean isFlexGrid) {
         SpectrumAssignmentBuilder spectrumAssignmentBldr = new SpectrumAssignmentBuilder()
             .setBeginIndex(Uint16.valueOf(0))
             .setStopIndex(Uint16.valueOf(0))
             .setFlexGrid(isFlexGrid);
         BitSet referenceBitSet = new BitSet(spectralWidthSlotNumber);
         referenceBitSet.set(0, spectralWidthSlotNumber);
-        int nbSteps = isFlexGrid ? spectralWidthSlotNumber : 1;
         //higher is the frequency, smallest is the wavelength number
         //in operational, the allocation is done through wavelength starting from the smallest
         //so we have to loop from the last element of the spectrum occupation
-        for (int i = spectrumOccupation.size(); i >= spectralWidthSlotNumber; i -= nbSteps) {
+        for (int i = spectrumOccupation.size(); i >= spectralWidthSlotNumber;
+                i -= isFlexGrid ? spectralWidthSlotNumber : 1) {
             if (spectrumOccupation.get(i - spectralWidthSlotNumber, i).equals(referenceBitSet)) {
                 spectrumAssignmentBldr.setBeginIndex(Uint16.valueOf(i - spectralWidthSlotNumber));
                 spectrumAssignmentBldr.setStopIndex(Uint16.valueOf(i - 1));