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/*
* Copyright 2015 Open Networking Laboratory
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.onosproject.bgp.controller.impl;
import java.util.Comparator;
import java.util.List;
import java.util.ListIterator;
import org.onosproject.bgpio.protocol.linkstate.PathAttrNlriDetailsLocalRib;
import org.onosproject.bgpio.types.AsPath;
import org.onosproject.bgpio.types.BgpValueType;
import org.onosproject.bgpio.types.LocalPref;
import org.onosproject.bgpio.types.Med;
import org.onosproject.bgpio.types.Origin;
import org.onosproject.bgpio.types.Origin.ORIGINTYPE;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
/**
* Implementation of BGP best path Selection process.
*/
public final class BgpSelectionAlgo implements Comparator<PathAttrNlriDetailsLocalRib> {
private static final Logger log = LoggerFactory.getLogger(BgpSelectionAlgo.class);
LocalPref obj1LocPref = null;
AsPath obj1Aspath = null;
Origin obj1Origin = null;
Med obj1Med = null;
LocalPref obj2LocPref = null;
AsPath obj2Aspath = null;
Origin obj2Origin = null;
Med obj2Med = null;
@Override
public int compare(PathAttrNlriDetailsLocalRib pathNlriDetails1, PathAttrNlriDetailsLocalRib pathNlriDetails2) {
if (pathNlriDetails1 == null) {
return -1;
}
if (pathNlriDetails2 == null) {
return 1;
}
if (pathNlriDetails1.equals(pathNlriDetails2)) {
return 0;
}
List<BgpValueType> o1 = pathNlriDetails1.localRibNlridetails().pathAttributes();
List<BgpValueType> o2 = pathNlriDetails2.localRibNlridetails().pathAttributes();
ListIterator<BgpValueType> listIteratorObj1 = o1.listIterator();
ListIterator<BgpValueType> listIteratorObj2 = o2.listIterator();
storeAttr(listIteratorObj1, listIteratorObj2);
// prefer attribute with higher local preference
if (obj1LocPref != null || obj2LocPref != null && (obj1LocPref != null && !obj1LocPref.equals(obj2LocPref))) {
return compareLocalPref(obj1LocPref, obj2LocPref);
}
// prefer attribute with shortest Aspath
if (!obj1Aspath.equals(obj2Aspath)) {
Integer obj1Size = countASSize(obj1Aspath);
Integer obj2Size = countASSize(obj2Aspath);
if (obj1Size != obj2Size) {
return compareAsPath(obj1Size, obj2Size);
}
}
// prefer attribute with lowest origin type
if (!obj1Origin.equals(obj2Origin)) {
return compareOrigin(obj1Origin, obj2Origin);
}
// prefer attribute with lowest MED
if (obj1Med != null || obj2Med != null && (obj1Med != null && !obj1Med.equals(obj2Med))) {
return compareMed(obj1Med, obj2Med);
}
if ((pathNlriDetails1 != null || pathNlriDetails2 != null) && (pathNlriDetails1 != null && !pathNlriDetails1
.equals(pathNlriDetails2))) {
return comparePeerDetails(pathNlriDetails1, pathNlriDetails2);
}
return 0;
}
/**
* Compares local preference of two objects and returns object with higher preference.
*
* @param obj1LocPref local preference object1
* @param obj2LocPref local preference object2
* @return object with higher preference
*/
int compareLocalPref(LocalPref obj1LocPref, LocalPref obj2LocPref) {
return ((Integer) (obj1LocPref.localPref())).compareTo((Integer) (obj2LocPref.localPref()));
}
/**
* Compares AsPath of two objects and returns object with shortest AsPath.
*
* @param obj1Size object1 AS count
* @param obj2Size object2 AS count
* @return
*/
int compareAsPath(Integer obj1Size, Integer obj2Size) {
return obj1Size.compareTo(obj2Size);
}
/**
* Compare Origin of two objects and returns object with lowest origin value.
*
* @param obj1Origin Origin object1
* @param obj2Origin Origin object1
* @return object with lowest origin value
*/
int compareOrigin(Origin obj1Origin, Origin obj2Origin) {
if (obj1Origin.origin() == ORIGINTYPE.IGP) {
return 1;
}
if (obj2Origin.origin() == ORIGINTYPE.IGP) {
return -1;
}
if (obj1Origin.origin() == ORIGINTYPE.EGP) {
return 1;
} else {
return -1;
}
}
/**
* Compare Med of two objects and returns object with lowestMed value.
*
* @param obj1Med Med object1
* @param obj2Med Med object2
* @return returns object with lowestMed value
*/
int compareMed(Med obj1Med, Med obj2Med) {
return ((Integer) (obj2Med.med())).compareTo((Integer) (obj1Med.med()));
}
/**
* Compares EBGP over IBGP, BGP identifier value and peer address.
*
* @param pathNlriDetails1 PathAttrNlriDetailsLocalRib object1
* @param pathNlriDetails2 PathAttrNlriDetailsLocalRib object2
* @return object which as EBGP over IBGP, lowest BGP identifier value and lowest peer address
*/
int comparePeerDetails(PathAttrNlriDetailsLocalRib pathNlriDetails1, PathAttrNlriDetailsLocalRib pathNlriDetails2) {
// consider EBGP over IBGP
if (pathNlriDetails1.isLocalRibIbgpSession() != pathNlriDetails2.isLocalRibIbgpSession()) {
if (pathNlriDetails1 == null || pathNlriDetails1.isLocalRibIbgpSession()) {
return -1;
}
if (pathNlriDetails2 == null || pathNlriDetails2.isLocalRibIbgpSession()) {
return 1;
}
}
// prefer lowest BGP identifier value.
if (pathNlriDetails1.localRibIdentifier() != pathNlriDetails2.localRibIdentifier()) {
return ((Integer) pathNlriDetails2.localRibIdentifier())
.compareTo(pathNlriDetails1.localRibIdentifier());
}
//prefer lowest peer address
if (pathNlriDetails1.localRibIpAddress() != pathNlriDetails2.localRibIpAddress()) {
return pathNlriDetails2.localRibIpAddress().compareTo(pathNlriDetails1.localRibIpAddress());
}
return 0;
}
/**
* Returns ASes count of AsPath attribute , if AS_SET is present then count as 1.
*
* @param aspath object of AsPath
* @return count of ASes
*/
Integer countASSize(AsPath aspath) {
boolean isASSet = false;
int count = 0;
if (!aspath.asPathSet().isEmpty()) {
isASSet = true;
}
if (!aspath.asPathSeq().isEmpty()) {
count = aspath.asPathSeq().size();
}
return isASSet ? ++count : count;
}
/**
* Stores BGP basic attributes of two objects.
*
* @param listIteratorObj1 list iterator of object1
* @param listIteratorObj2 list iterator of object2
*/
void storeAttr(ListIterator<BgpValueType> listIteratorObj1, ListIterator<BgpValueType> listIteratorObj2) {
while (listIteratorObj1.hasNext()) {
BgpValueType pathAttributeObj1 = listIteratorObj1.next();
switch (pathAttributeObj1.getType()) {
case LocalPref.LOCAL_PREF_TYPE:
obj1LocPref = (LocalPref) pathAttributeObj1;
break;
case AsPath.ASPATH_TYPE:
obj1Aspath = (AsPath) pathAttributeObj1;
break;
case Origin.ORIGIN_TYPE:
obj1Origin = (Origin) pathAttributeObj1;
break;
case Med.MED_TYPE:
obj1Med = (Med) pathAttributeObj1;
break;
default:
log.debug("Got other type, Not required: " + pathAttributeObj1.getType());
}
}
while (listIteratorObj2.hasNext()) {
BgpValueType pathAttributeObj2 = listIteratorObj2.next();
switch (pathAttributeObj2.getType()) {
case LocalPref.LOCAL_PREF_TYPE:
obj2LocPref = (LocalPref) pathAttributeObj2;
break;
case AsPath.ASPATH_TYPE:
obj2Aspath = (AsPath) pathAttributeObj2;
break;
case Origin.ORIGIN_TYPE:
obj2Origin = (Origin) pathAttributeObj2;
break;
case Med.MED_TYPE:
obj2Med = (Med) pathAttributeObj2;
break;
default:
log.debug("Got other type, Not required: " + pathAttributeObj2.getType());
}
}
}
}
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