diff --git a/core/net/src/main/java/org/onosproject/net/pi/impl/PiMulticastGroupTranslatorImpl.java b/core/net/src/main/java/org/onosproject/net/pi/impl/PiMulticastGroupTranslatorImpl.java
new file mode 100644
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--- /dev/null
+++ b/core/net/src/main/java/org/onosproject/net/pi/impl/PiMulticastGroupTranslatorImpl.java
@@ -0,0 +1,107 @@
+/*
+ * Copyright 2018-present Open Networking Foundation
+ *
+ * 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.net.pi.impl;
+
+import com.google.common.collect.Maps;
+import com.google.common.collect.Sets;
+import org.onosproject.net.PortNumber;
+import org.onosproject.net.flow.instructions.Instruction;
+import org.onosproject.net.flow.instructions.Instructions.OutputInstruction;
+import org.onosproject.net.group.Group;
+import org.onosproject.net.group.GroupDescription;
+import org.onosproject.net.pi.runtime.PiMulticastGroupEntry;
+import org.onosproject.net.pi.runtime.PiPreReplica;
+import org.onosproject.net.pi.service.PiTranslationException;
+
+import java.util.Collection;
+import java.util.List;
+import java.util.Map;
+import java.util.Set;
+import java.util.stream.Collectors;
+
+import static com.google.common.base.Preconditions.checkNotNull;
+import static java.lang.String.format;
+
+/**
+ * Implementation of multicast group translation logic.
+ */
+final class PiMulticastGroupTranslatorImpl {
+
+    private PiMulticastGroupTranslatorImpl() {
+        // Hides constructor.
+    }
+
+    /**
+     * Returns a PI PRE multicast group entry equivalent to the given group, for
+     * the given pipeconf and device.
+     * <p>
+     * The passed group is expected to have type {@link GroupDescription.Type#ALL}.
+     *
+     * @param group    group
+     * @return PI PRE entry
+     * @throws PiTranslationException if the group cannot be translated
+     */
+    static PiMulticastGroupEntry translate(Group group)
+            throws PiTranslationException {
+
+        checkNotNull(group);
+
+        if (!group.type().equals(GroupDescription.Type.ALL)) {
+            throw new PiTranslationException(format(
+                    "group type %s not supported", group.type()));
+        }
+
+        final List<Instruction> instructions = group.buckets().buckets().stream()
+                .flatMap(b -> b.treatment().allInstructions().stream())
+                .collect(Collectors.toList());
+
+        final boolean hasNonOutputInstr = instructions.stream()
+                .anyMatch(i -> !i.type().equals(Instruction.Type.OUTPUT));
+
+        if (instructions.size() != group.buckets().buckets().size()
+                || hasNonOutputInstr) {
+            throw new PiTranslationException(
+                    "support only groups with just one OUTPUT instruction per bucket");
+        }
+
+        final List<OutputInstruction> outInstructions = instructions.stream()
+                .map(i -> (OutputInstruction) i)
+                .collect(Collectors.toList());
+
+        return PiMulticastGroupEntry.builder()
+                .withGroupId(group.id().id())
+                .addReplicas(getReplicas(outInstructions))
+                .build();
+    }
+
+    private static Set<PiPreReplica> getReplicas(Collection<OutputInstruction> instructions) {
+        // Account for multiple replicas for the same port.
+        final Map<PortNumber, Set<PiPreReplica>> replicaMap = Maps.newHashMap();
+        final List<PortNumber> ports = instructions.stream()
+                .map(OutputInstruction::port)
+                .collect(Collectors.toList());
+        for (PortNumber port : ports) {
+            replicaMap.putIfAbsent(port, Sets.newHashSet());
+            // Use incremental instance IDs for replicas of the same port.
+            replicaMap.get(port).add(
+                    new PiPreReplica(port, replicaMap.get(port).size() + 1));
+        }
+        return replicaMap.values().stream()
+                .flatMap(Collection::stream)
+                .collect(Collectors.toSet());
+    }
+}