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