pce/src/main/java/org/opendaylight/transportpce/pce/graph/PostAlgoPathValidator.java

   1 /*
   2  * Copyright © 2017 AT&T, Inc. and others.  All rights reserved.
   3  *
   4  * This program and the accompanying materials are made available under the
   5  * terms of the Eclipse Public License v1.0 which accompanies this distribution,
   6  * and is available at http://www.eclipse.org/legal/epl-v10.html
   7  */
   8
   9 package org.opendaylight.transportpce.pce.graph;
  10
  11 import edu.umd.cs.findbugs.annotations.SuppressFBWarnings;
  12 import java.util.ArrayList;
  13 import java.util.Arrays;
  14 import java.util.BitSet;
  15 import java.util.Collections;
  16 import java.util.HashMap;
  17 import java.util.List;
  18 import java.util.Map;
  19 import org.jgrapht.GraphPath;
  20 import org.opendaylight.transportpce.common.ResponseCodes;
  21 import org.opendaylight.transportpce.common.StringConstants;
  22 import org.opendaylight.transportpce.common.fixedflex.GridConstant;
  23 import org.opendaylight.transportpce.common.fixedflex.GridUtils;
  24 import org.opendaylight.transportpce.pce.constraints.PceConstraints;
  25 import org.opendaylight.transportpce.pce.constraints.PceConstraints.ResourcePair;
  26 import org.opendaylight.transportpce.pce.networkanalyzer.PceNode;
  27 import org.opendaylight.transportpce.pce.networkanalyzer.PceResult;
  28 import org.opendaylight.yang.gen.v1.http.org.opendaylight.transportpce.pce.rev210701.SpectrumAssignment;
  29 import org.opendaylight.yang.gen.v1.http.org.opendaylight.transportpce.pce.rev210701.SpectrumAssignmentBuilder;
  30 import org.opendaylight.yang.gen.v1.http.org.openroadm.network.types.rev200529.OpenroadmLinkType;
  31 import org.opendaylight.yang.gen.v1.http.org.openroadm.otn.common.types.rev181130.OpucnTribSlotDef;
  32 import org.opendaylight.yang.gen.v1.urn.ietf.params.xml.ns.yang.ietf.network.rev180226.NodeId;
  33 import org.opendaylight.yangtools.yang.common.Uint16;
  34 import org.slf4j.Logger;
  35 import org.slf4j.LoggerFactory;
  36
  37 public class PostAlgoPathValidator {
  38     /* Logging. */
  39     private static final Logger LOG = LoggerFactory.getLogger(PostAlgoPathValidator.class);
  40
  41     private static final double MIN_OSNR_W100G = 17;
  42     private static final double TRX_OSNR = 33;
  43     private static final double ADD_OSNR = 30;
  44     public static final Long CONST_OSNR = 1L;
  45     public static final double SYS_MARGIN = 0;
  46
  47     @SuppressWarnings("fallthrough")
  48     @SuppressFBWarnings(
  49         value = "SF_SWITCH_FALLTHROUGH",
  50         justification = "intentional fallthrough")
  51     public PceResult checkPath(GraphPath<String, PceGraphEdge> path, Map<NodeId, PceNode> allPceNodes,
  52         PceResult pceResult, PceConstraints pceHardConstraints, String serviceType) {
  53
  54         // check if the path is empty
  55         if (path.getEdgeList().isEmpty()) {
  56             pceResult.setRC(ResponseCodes.RESPONSE_FAILED);
  57             return pceResult;
  58         }
  59         int spectralWidthSlotNumber = GridConstant.SPECTRAL_WIDTH_SLOT_NUMBER_MAP
  60             .getOrDefault(serviceType, GridConstant.NB_SLOTS_100G);
  61         SpectrumAssignment spectrumAssignment = null;
  62         //variable to deal with 1GE (Nb=1) and 10GE (Nb=10) cases
  63         switch (serviceType) {
  64             case StringConstants.SERVICE_TYPE_OTUC4:
  65             case StringConstants.SERVICE_TYPE_400GE:
  66                 spectralWidthSlotNumber = GridConstant.SPECTRAL_WIDTH_SLOT_NUMBER_MAP
  67                     .getOrDefault(serviceType, GridConstant.NB_SLOTS_400G);
  68             //fallthrough
  69             case StringConstants.SERVICE_TYPE_100GE_T:
  70             case StringConstants.SERVICE_TYPE_OTU4:
  71                 spectrumAssignment = getSpectrumAssignment(path, allPceNodes, spectralWidthSlotNumber);
  72                 pceResult.setServiceType(serviceType);
  73                 if (spectrumAssignment.getBeginIndex().equals(Uint16.valueOf(0))
  74                         && spectrumAssignment.getStopIndex().equals(Uint16.valueOf(0))) {
  75                     pceResult.setRC(ResponseCodes.RESPONSE_FAILED);
  76                     pceResult.setLocalCause(PceResult.LocalCause.NO_PATH_EXISTS);
  77                     return pceResult;
  78                 }
  79                 if (spectrumAssignment.getFlexGrid()) {
  80                     LOG.info("Spectrum assignment flexgrid mode");
  81                     pceResult.setResultWavelength(GridConstant.IRRELEVANT_WAVELENGTH_NUMBER);
  82                 } else {
  83                     LOG.info("Spectrum assignment fixedgrid mode");
  84                     pceResult.setResultWavelength(
  85                             GridUtils.getWaveLengthIndexFromSpectrumAssigment(spectrumAssignment.getBeginIndex()
  86                                 .toJava()));
  87                 }
  88                 pceResult.setMinFreq(GridUtils.getStartFrequencyFromIndex(spectrumAssignment.getBeginIndex().toJava()));
  89                 pceResult.setMaxFreq(GridUtils.getStopFrequencyFromIndex(spectrumAssignment.getStopIndex().toJava()));
  90                 LOG.info("In PostAlgoPathValidator: spectrum assignment found {} {}", spectrumAssignment, path);
  91
  92                 // Check the OSNR
  93                 if (!checkOSNR(path)) {
  94                     pceResult.setRC(ResponseCodes.RESPONSE_FAILED);
  95                     pceResult.setLocalCause(PceResult.LocalCause.OUT_OF_SPEC_OSNR);
  96                     return pceResult;
  97                 }
  98
  99                 // Check if MaxLatency is defined in the hard constraints
 100                 if ((pceHardConstraints.getMaxLatency() != -1)
 101                         && (!checkLatency(pceHardConstraints.getMaxLatency(), path))) {
 102                     pceResult.setRC(ResponseCodes.RESPONSE_FAILED);
 103                     pceResult.setLocalCause(PceResult.LocalCause.TOO_HIGH_LATENCY);
 104                     return pceResult;
 105                 }
 106
 107                 // Check if nodes are included in the hard constraints
 108                 if (!checkInclude(path, pceHardConstraints)) {
 109                     pceResult.setRC(ResponseCodes.RESPONSE_FAILED);
 110                     pceResult.setLocalCause(PceResult.LocalCause.HD_NODE_INCLUDE);
 111                     return pceResult;
 112                 }
 113
 114                 // TODO here other post algo validations can be added
 115                 // more data can be sent to PceGraph module via PceResult structure if required
 116
 117                 pceResult.setRC(ResponseCodes.RESPONSE_OK);
 118                 pceResult.setLocalCause(PceResult.LocalCause.NONE);
 119                 break;
 120             case StringConstants.SERVICE_TYPE_100GE_M:
 121             case StringConstants.SERVICE_TYPE_10GE:
 122             case StringConstants.SERVICE_TYPE_1GE:
 123                 Map<String, Integer> tribSlotNbMap = Map.of(
 124                     StringConstants.SERVICE_TYPE_100GE_M, 20,
 125                     StringConstants.SERVICE_TYPE_10GE, 8,
 126                     StringConstants.SERVICE_TYPE_1GE, 1);
 127                 int tribSlotNb = tribSlotNbMap.get(serviceType);
 128                 pceResult.setRC(ResponseCodes.RESPONSE_FAILED);
 129                 pceResult.setServiceType(serviceType);
 130                 Map<String, List<Uint16>> tribSlot = chooseTribSlot(path, allPceNodes, tribSlotNb);
 131                 Map<String, Uint16> tribPort = chooseTribPort(path, allPceNodes, tribSlot, tribSlotNb);
 132                 List<OpucnTribSlotDef> resultTribPortTribSlot = getMinMaxTpTs(tribPort, tribSlot);
 133
 134                 if (resultTribPortTribSlot.get(0) != null && resultTribPortTribSlot.get(1) != null) {
 135                     pceResult.setResultTribPortTribSlot(resultTribPortTribSlot);
 136                     pceResult.setRC(ResponseCodes.RESPONSE_OK);
 137                     LOG.info("In PostAlgoPathValidator: found TribPort {} - tribSlot {} - tribSlotNb {}",
 138                         tribPort, tribSlot, tribSlotNb);
 139                 }
 140                 break;
 141             case StringConstants.SERVICE_TYPE_ODU4:
 142             case StringConstants.SERVICE_TYPE_ODUC4:
 143             case StringConstants.SERVICE_TYPE_100GE_S:
 144                 pceResult.setRC(ResponseCodes.RESPONSE_OK);
 145                 pceResult.setServiceType(serviceType);
 146                 LOG.info("In PostAlgoPathValidator: ODU4/ODUC4 path found {}", path);
 147                 break;
 148             default:
 149                 pceResult.setRC(ResponseCodes.RESPONSE_FAILED);
 150                 LOG.warn("In PostAlgoPathValidator checkPath: unsupported serviceType {} found {}",
 151                     serviceType, path);
 152                 break;
 153         }
 154         return pceResult;
 155     }
 156
 157     // Check the latency
 158     private boolean checkLatency(Long maxLatency, GraphPath<String, PceGraphEdge> path) {
 159         double latency = 0;
 160
 161         for (PceGraphEdge edge : path.getEdgeList()) {
 162             try {
 163                 latency += edge.link().getLatency();
 164                 LOG.debug("- In checkLatency: latency of {} = {} units", edge.link().getLinkId().getValue(), latency);
 165             } catch (NullPointerException e) {
 166                 LOG.warn("- In checkLatency: the link {} does not contain latency field",
 167                     edge.link().getLinkId().getValue());
 168             }
 169         }
 170         return (latency < maxLatency);
 171     }
 172
 173     // Check the inclusion if it is defined in the hard constraints
 174     private boolean checkInclude(GraphPath<String, PceGraphEdge> path, PceConstraints pceHardConstraintsInput) {
 175         List<ResourcePair> listToInclude = pceHardConstraintsInput.getListToInclude();
 176         if (listToInclude.isEmpty()) {
 177             return true;
 178         }
 179
 180         List<PceGraphEdge> pathEdges = path.getEdgeList();
 181         LOG.debug(" in checkInclude vertex list: [{}]", path.getVertexList());
 182
 183         List<String> listOfElementsSubNode = new ArrayList<>();
 184         listOfElementsSubNode.add(pathEdges.get(0).link().getsourceNetworkSupNodeId());
 185         listOfElementsSubNode.addAll(listOfElementsBuild(pathEdges, PceConstraints.ResourceType.NODE,
 186             pceHardConstraintsInput));
 187
 188         List<String> listOfElementsCLLI = new ArrayList<>();
 189         listOfElementsCLLI.add(pathEdges.get(0).link().getsourceCLLI());
 190         listOfElementsCLLI.addAll(listOfElementsBuild(pathEdges, PceConstraints.ResourceType.CLLI,
 191             pceHardConstraintsInput));
 192
 193         List<String> listOfElementsSRLG = new ArrayList<>();
 194         // first link is XPONDEROUTPUT, no SRLG for it
 195         listOfElementsSRLG.add("NONE");
 196         listOfElementsSRLG.addAll(listOfElementsBuild(pathEdges, PceConstraints.ResourceType.SRLG,
 197             pceHardConstraintsInput));
 198
 199         // validation: check each type for each element
 200         for (ResourcePair next : listToInclude) {
 201             int indx = -1;
 202             switch (next.getType()) {
 203                 case NODE:
 204                     if (listOfElementsSubNode.contains(next.getName())) {
 205                         indx = listOfElementsSubNode.indexOf(next.getName());
 206                     }
 207                     break;
 208                 case SRLG:
 209                     if (listOfElementsSRLG.contains(next.getName())) {
 210                         indx = listOfElementsSRLG.indexOf(next.getName());
 211                     }
 212                     break;
 213                 case CLLI:
 214                     if (listOfElementsCLLI.contains(next.getName())) {
 215                         indx = listOfElementsCLLI.indexOf(next.getName());
 216                     }
 217                     break;
 218                 default:
 219                     LOG.warn(" in checkInclude vertex list unsupported resource type: [{}]", next.getType());
 220             }
 221
 222             if (indx < 0) {
 223                 LOG.debug(" in checkInclude stopped : {} ", next.getName());
 224                 return false;
 225             }
 226
 227             LOG.debug(" in checkInclude next found {} in {}", next.getName(), path.getVertexList());
 228
 229             listOfElementsSubNode.subList(0, indx).clear();
 230             listOfElementsCLLI.subList(0, indx).clear();
 231             listOfElementsSRLG.subList(0, indx).clear();
 232         }
 233
 234         LOG.info(" in checkInclude passed : {} ", path.getVertexList());
 235         return true;
 236     }
 237
 238     private List<String> listOfElementsBuild(List<PceGraphEdge> pathEdges, PceConstraints.ResourceType type,
 239         PceConstraints pceHardConstraints) {
 240
 241         List<String> listOfElements = new ArrayList<>();
 242         for (PceGraphEdge link : pathEdges) {
 243             switch (type) {
 244                 case NODE:
 245                     listOfElements.add(link.link().getdestNetworkSupNodeId());
 246                     break;
 247                 case CLLI:
 248                     listOfElements.add(link.link().getdestCLLI());
 249                     break;
 250                 case SRLG:
 251                     if (link.link().getlinkType() != OpenroadmLinkType.ROADMTOROADM) {
 252                         listOfElements.add("NONE");
 253                         break;
 254                     }
 255                     // srlg of link is List<Long>. But in this algo we need string representation of
 256                     // one SRLG
 257                     // this should be any SRLG mentioned in include constraints if any of them if
 258                     // mentioned
 259                     boolean found = false;
 260                     for (Long srlg : link.link().getsrlgList()) {
 261                         String srlgStr = String.valueOf(srlg);
 262                         if (pceHardConstraints.getSRLGnames().contains(srlgStr)) {
 263                             listOfElements.add(srlgStr);
 264                             LOG.info("listOfElementsBuild. FOUND SRLG {} in link {}", srlgStr, link.link());
 265                             found = true;
 266                         }
 267                     }
 268                     if (!found) {
 269                         // there is no specific srlg to include. thus add to list just the first one
 270                         listOfElements.add("NONE");
 271                     }
 272                     break;
 273                 default:
 274                     LOG.debug("listOfElementsBuild unsupported resource type");
 275             }
 276         }
 277         return listOfElements;
 278     }
 279
 280     private Map<String, Uint16> chooseTribPort(GraphPath<String,
 281         PceGraphEdge> path, Map<NodeId, PceNode> allPceNodes, Map<String, List<Uint16>> tribSlotMap, int nbSlot) {
 282         LOG.info("In choosetribPort: edgeList = {} ", path.getEdgeList());
 283         Map<String, Uint16> tribPortMap = new HashMap<>();
 284
 285         for (PceGraphEdge edge : path.getEdgeList()) {
 286             NodeId linkSrcNode = edge.link().getSourceId();
 287             String linkSrcTp = edge.link().getSourceTP().getValue();
 288             NodeId linkDestNode = edge.link().getDestId();
 289             String linkDestTp = edge.link().getDestTP().getValue();
 290             PceNode pceOtnNodeSrc = allPceNodes.get(linkSrcNode);
 291             PceNode pceOtnNodeDest = allPceNodes.get(linkDestNode);
 292             List<Uint16> srcTpnPool = pceOtnNodeSrc.getAvailableTribPorts().get(linkSrcTp);
 293             List<Uint16> destTpnPool = pceOtnNodeDest.getAvailableTribPorts().get(linkDestTp);
 294             List<Uint16> commonEdgeTpnPool = new ArrayList<>();
 295             for (Uint16 srcTpn : srcTpnPool) {
 296                 if (destTpnPool.contains(srcTpn)) {
 297                     commonEdgeTpnPool.add(srcTpn);
 298                 }
 299             }
 300             Collections.sort(commonEdgeTpnPool);
 301             if (!commonEdgeTpnPool.isEmpty()) {
 302                 Integer startTribSlot = tribSlotMap.values().stream().findFirst().get().get(0).toJava();
 303                 Integer tribPort = (int) Math.ceil((double)startTribSlot / nbSlot);
 304                 for (Uint16 commonTribPort : commonEdgeTpnPool) {
 305                     if (tribPort.equals(commonTribPort.toJava())) {
 306                         tribPortMap.put(edge.link().getLinkId().getValue(), commonTribPort);
 307                     }
 308                 }
 309             }
 310         }
 311         tribPortMap.forEach((k,v) -> LOG.info("TribPortMap : k = {}, v = {}", k, v));
 312         return tribPortMap;
 313     }
 314
 315     private Map<String, List<Uint16>> chooseTribSlot(GraphPath<String,
 316         PceGraphEdge> path, Map<NodeId, PceNode> allPceNodes, int nbSlot) {
 317         LOG.info("In choosetribSlot: edgeList = {} ", path.getEdgeList());
 318         Map<String, List<Uint16>> tribSlotMap = new HashMap<>();
 319
 320         for (PceGraphEdge edge : path.getEdgeList()) {
 321             NodeId linkSrcNode = edge.link().getSourceId();
 322             String linkSrcTp = edge.link().getSourceTP().getValue();
 323             NodeId linkDestNode = edge.link().getDestId();
 324             String linkDestTp = edge.link().getDestTP().getValue();
 325             PceNode pceOtnNodeSrc = allPceNodes.get(linkSrcNode);
 326             PceNode pceOtnNodeDest = allPceNodes.get(linkDestNode);
 327             List<Uint16> srcTsPool = pceOtnNodeSrc.getAvailableTribSlots().get(linkSrcTp);
 328             List<Uint16> destTsPool = pceOtnNodeDest.getAvailableTribSlots().get(linkDestTp);
 329             List<Uint16> commonEdgeTsPoolList = new ArrayList<>();
 330             List<Uint16> tribSlotList = new ArrayList<>();
 331             for (Uint16 integer : srcTsPool) {
 332                 if (destTsPool.contains(integer)) {
 333                     commonEdgeTsPoolList.add(integer);
 334                 }
 335             }
 336             Collections.sort(commonEdgeTsPoolList);
 337             List<Uint16> commonGoodStartEdgeTsPoolList = new ArrayList<>();
 338             for (Uint16 startEdgeTsPool : commonEdgeTsPoolList) {
 339                 if (Integer.valueOf(1).equals(startEdgeTsPool.toJava() % nbSlot)
 340                         || nbSlot == 1) {
 341                     commonGoodStartEdgeTsPoolList.add(startEdgeTsPool);
 342                 }
 343             }
 344             Collections.sort(commonGoodStartEdgeTsPoolList);
 345             boolean goodTsList = false;
 346             for (Uint16 goodStartTsPool : commonGoodStartEdgeTsPoolList) {
 347                 int goodStartIndex = commonEdgeTsPoolList.indexOf(Uint16.valueOf(goodStartTsPool.intValue()));
 348                 if (!goodTsList && commonEdgeTsPoolList.size() - goodStartIndex >= nbSlot) {
 349                     for (int i = 0; i < nbSlot; i++) {
 350                         if (!commonEdgeTsPoolList.get(goodStartIndex + i)
 351                                 .equals(Uint16.valueOf(goodStartTsPool.toJava() + i))) {
 352                             goodTsList = false;
 353                             tribSlotList.clear();
 354                             break;
 355                         }
 356                         tribSlotList.add(commonEdgeTsPoolList.get(goodStartIndex + i));
 357                         goodTsList = true;
 358                     }
 359                 }
 360             }
 361             tribSlotMap.put(edge.link().getLinkId().getValue(), tribSlotList);
 362         }
 363         tribSlotMap.forEach((k,v) -> LOG.info("TribSlotMap : k = {}, v = {}", k, v));
 364         return tribSlotMap;
 365     }
 366
 367     private List<OpucnTribSlotDef> getMinMaxTpTs(Map<String, Uint16> tribPort, Map<String, List<Uint16>> tribSlot) {
 368         String tribport = tribPort.values().toArray()[0].toString();
 369         @SuppressWarnings("unchecked")
 370         List<Uint16> tsList = (List<Uint16>) tribSlot.values().toArray()[0];
 371         OpucnTribSlotDef minOpucnTs = OpucnTribSlotDef
 372             .getDefaultInstance(String.join(".", tribport, tsList.get(0).toString()));
 373         OpucnTribSlotDef maxOpucnTs = OpucnTribSlotDef
 374             .getDefaultInstance(String.join(".", tribport, tsList.get(tsList.size() - 1).toString()));
 375         List<OpucnTribSlotDef> minmaxTpTsList = new ArrayList<>();
 376         minmaxTpTsList.add(minOpucnTs);
 377         minmaxTpTsList.add(maxOpucnTs);
 378         return minmaxTpTsList;
 379     }
 380
 381     // Check the path OSNR
 382     private boolean checkOSNR(GraphPath<String, PceGraphEdge> path) {
 383         double linkOsnrDb;
 384         double osnrDb = 0;
 385         LOG.info("- In checkOSNR: OSNR of the transmitter = {} dB", TRX_OSNR);
 386         LOG.info("- In checkOSNR: add-path incremental OSNR = {} dB", ADD_OSNR);
 387         double inverseLocalOsnr = getInverseOsnrLinkLu(TRX_OSNR) + getInverseOsnrLinkLu(ADD_OSNR);
 388         for (PceGraphEdge edge : path.getEdgeList()) {
 389             if (edge.link().getlinkType() == OpenroadmLinkType.ROADMTOROADM) {
 390                 // link OSNR in dB
 391                 linkOsnrDb = edge.link().getosnr();
 392                 LOG.info("- In checkOSNR: OSNR of {} = {} dB", edge.link().getLinkId().getValue(), linkOsnrDb);
 393                 // 1 over the local OSNR, in linear units
 394                 inverseLocalOsnr += getInverseOsnrLinkLu(linkOsnrDb);
 395             }
 396         }
 397         try {
 398             osnrDb = getOsnrDb(1 / inverseLocalOsnr);
 399         } catch (ArithmeticException e) {
 400             LOG.debug("In checkOSNR: OSNR is equal to 0 and the number of links is: {}", path.getEdgeList().size());
 401             return false;
 402         }
 403         LOG.info("In checkOSNR: OSNR of the path is {} dB", osnrDb);
 404         return ((osnrDb + SYS_MARGIN) > MIN_OSNR_W100G);
 405     }
 406
 407     private double getOsnrDb(double osnrLu) {
 408         return (10 * Math.log10(osnrLu));
 409     }
 410
 411     private double getInverseOsnrLinkLu(double linkOsnrDb) {
 412         // 1 over the link OSNR, in linear units
 413         double linkOsnrLu = Math.pow(10, (linkOsnrDb / 10.0));
 414         LOG.debug("In retrieveosnr: the inverse of link osnr is {} (Linear Unit)", linkOsnrLu);
 415         return (CONST_OSNR / linkOsnrLu);
 416     }
 417
 418     /**
 419      * Get spectrum assignment for path.
 420      *
 421      * @param path                    the path for which we get spectrum assignment.
 422      * @param allPceNodes             all optical nodes.
 423      * @param spectralWidthSlotNumber number of slot for spectral width. Depends on
 424      *                                service type.
 425      * @return a spectrum assignment object which contains begin and end index. If
 426      *         no spectrum assignment found, beginIndex = stopIndex = 0
 427      */
 428     private SpectrumAssignment getSpectrumAssignment(GraphPath<String, PceGraphEdge> path,
 429             Map<NodeId, PceNode> allPceNodes, int spectralWidthSlotNumber) {
 430         byte[] freqMap = new byte[GridConstant.NB_OCTECTS];
 431         Arrays.fill(freqMap, (byte) GridConstant.AVAILABLE_SLOT_VALUE);
 432         BitSet result = BitSet.valueOf(freqMap);
 433         boolean isFlexGrid = true;
 434         LOG.info("Processing path {} with length {}", path, path.getLength());
 435         BitSet pceNodeFreqMap;
 436         for (PceGraphEdge edge : path.getEdgeList()) {
 437             LOG.info("Processing source {} ", edge.link().getSourceId());
 438             if (allPceNodes.containsKey(edge.link().getSourceId())) {
 439                 PceNode pceNode = allPceNodes.get(edge.link().getSourceId());
 440                 LOG.info("Processing PCE node {}", pceNode);
 441                 if (StringConstants.OPENROADM_DEVICE_VERSION_1_2_1.equals(pceNode.getVersion())) {
 442                     LOG.info("Node {}: version is {} and slot width granularity is {} -> fixed grid mode",
 443                         pceNode.getNodeId(), pceNode.getVersion(), pceNode.getSlotWidthGranularity());
 444                     isFlexGrid = false;
 445                 }
 446                 if ((pceNode.getSlotWidthGranularity().equals(GridConstant.SLOT_WIDTH_50))
 447                     && (pceNode.getCentralFreqGranularity().equals(GridConstant.SLOT_WIDTH_50))) {
 448                     LOG.info("Node {}: version is {} with slot width granularity  {} and central "
 449                             + "frequency granularity is {} -> fixed grid mode",
 450                         pceNode.getNodeId(), pceNode.getVersion(), pceNode.getSlotWidthGranularity(),
 451                         pceNode.getCentralFreqGranularity());
 452                     isFlexGrid = false;
 453                 }
 454                 pceNodeFreqMap = pceNode.getBitSetData();
 455                 LOG.debug("Pce node bitset {}", pceNodeFreqMap);
 456                 if (pceNodeFreqMap != null) {
 457                     result.and(pceNodeFreqMap);
 458                     LOG.debug("intermediate bitset {}", result);
 459                 }
 460             }
 461         }
 462         LOG.debug("Bitset result {}", result);
 463         return computeBestSpectrumAssignment(result, spectralWidthSlotNumber, isFlexGrid);
 464     }
 465
 466     /**
 467      * Compute spectrum assignment from spectrum occupation for spectral width.
 468      *
 469      * @param spectrumOccupation      the spectrum occupation BitSet.
 470      * @param spectralWidthSlotNumber the nb slots for spectral width.
 471      * @param isFlexGrid              true if flexible grid, false otherwise.
 472      * @return a spectrum assignment object which contains begin and stop index. If
 473      *         no spectrum assignment found, beginIndex = stopIndex = 0
 474      */
 475     private SpectrumAssignment computeBestSpectrumAssignment(BitSet spectrumOccupation, int spectralWidthSlotNumber,
 476             boolean isFlexGrid) {
 477         SpectrumAssignmentBuilder spectrumAssignmentBldr = new SpectrumAssignmentBuilder()
 478             .setBeginIndex(Uint16.valueOf(0))
 479             .setStopIndex(Uint16.valueOf(0))
 480             .setFlexGrid(isFlexGrid);
 481         BitSet referenceBitSet = new BitSet(spectralWidthSlotNumber);
 482         referenceBitSet.set(0, spectralWidthSlotNumber);
 483         int nbSteps = isFlexGrid ? spectralWidthSlotNumber : 1;
 484         //higher is the frequency, smallest is the wavelength number
 485         //in operational, the allocation is done through wavelength starting from the smallest
 486         //so we have to loop from the last element of the spectrum occupation
 487         for (int i = spectrumOccupation.size(); i >= spectralWidthSlotNumber; i -= nbSteps) {
 488             if (spectrumOccupation.get(i - spectralWidthSlotNumber, i).equals(referenceBitSet)) {
 489                 spectrumAssignmentBldr.setBeginIndex(Uint16.valueOf(i - spectralWidthSlotNumber));
 490                 spectrumAssignmentBldr.setStopIndex(Uint16.valueOf(i - 1));
 491                 break;
 492             }
 493         }
 494         return spectrumAssignmentBldr.build();
 495     }
 496 }