diff --git a/src/main/java/net/onrc/onos/core/devicemanager/OnosDevice.java b/src/main/java/net/onrc/onos/core/devicemanager/OnosDevice.java
new file mode 100644
index 0000000..4e6a8dc
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+++ b/src/main/java/net/onrc/onos/core/devicemanager/OnosDevice.java
@@ -0,0 +1,264 @@
+/**
+l*    Copyright 2011,2012, Big Switch Networks, Inc. 
+*    Originally created by David Erickson, Stanford University
+* 
+*    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 net.onrc.onos.core.devicemanager;
+
+import java.io.Serializable;
+import java.util.Date;
+
+import net.floodlightcontroller.util.MACAddress;
+import net.onrc.onos.packet.IPv4;
+
+/**
+ * An entity on the network is a visible trace of a device that corresponds
+ * to a packet received from a particular interface on the edge of a network,
+ * with a particular VLAN tag, and a particular MAC address, along with any
+ * other packet characteristics we might want to consider as helpful for
+ * disambiguating devices.
+ * 
+ * Entities are the most basic element of devices; devices consist of one or
+ * more entities.  Entities are immutable once created, except for the last
+ * seen timestamp.
+ *  
+ * @author readams
+ *
+ */
+public class OnosDevice implements Serializable { //implements Comparable<OnosDevice> {
+
+    private static int ACTIVITY_TIMEOUT = 30000;
+    
+    /**
+     * The MAC address associated with this entity
+     */
+    private MACAddress macAddress;
+    
+    /**
+     * The IP address associated with this entity, or null if no IP learned
+     * from the network observation associated with this entity
+     */
+    private Integer ipv4Address;
+    
+    /**
+     * The VLAN tag on this entity, or null if untagged
+     */
+    private Short vlan;
+    
+    /**
+     * The DPID of the switch for the ingress point for this entity,
+     * or null if not present
+     */
+    private long switchDPID;
+    
+    /**
+     * The port number of the switch for the ingress point for this entity,
+     * or null if not present
+     */
+    private short switchPort;
+    
+    /**
+     * The last time we observed this entity on the network
+     */
+    private Date lastSeenTimestamp;
+
+    private Date activeSince;
+    
+    private int hashCode = 0;
+
+    // ************
+    // Constructors
+    // ************
+     protected OnosDevice() {}
+     
+    /**
+     * Create a new entity
+     * 
+     * @param macAddress
+     * @param vlan
+     * @param ipv4Address
+     * @param switchDPID
+     * @param switchPort
+     * @param lastSeenTimestamp
+     */
+    public OnosDevice(MACAddress macAddress, Short vlan, 
+                  Integer ipv4Address, Long switchDPID, short switchPort, 
+                  Date lastSeenTimestamp) {
+        this.macAddress = macAddress;
+        this.ipv4Address = ipv4Address;
+        this.vlan = vlan;
+        this.switchDPID = switchDPID;
+        this.switchPort = switchPort;
+        this.lastSeenTimestamp = lastSeenTimestamp;
+        this.activeSince = lastSeenTimestamp;
+    }
+
+    // ***************
+    // Getters/Setters
+    // ***************
+
+    public MACAddress getMacAddress() {
+        return macAddress;
+    }
+
+    public Integer getIpv4Address() {
+        return ipv4Address;
+    }
+    
+    public void setIpv4Address(Integer ipv4Address) {
+    	this.ipv4Address = ipv4Address;
+    }
+
+    public Short getVlan() {
+        return vlan;
+    }
+
+    public Long getSwitchDPID() {
+        return switchDPID;
+    }
+    
+    public void setSwitchDPID(long dpid) {
+    	this.switchDPID = dpid;
+    }
+
+    public short getSwitchPort() {
+        return switchPort;
+    }
+    
+    public void setSwitchPort(short port) {
+    	this.switchPort = port;
+    }
+
+    public Date getLastSeenTimestamp() {
+        return lastSeenTimestamp;
+    }
+
+    
+    public void setLastSeenTimestamp(Date lastSeenTimestamp) {
+        if (activeSince == null ||
+            (activeSince.getTime() +  ACTIVITY_TIMEOUT) <
+                lastSeenTimestamp.getTime())
+            this.activeSince = lastSeenTimestamp;
+        this.lastSeenTimestamp = lastSeenTimestamp;
+    }
+
+    public Date getActiveSince() {
+        return activeSince;
+    }
+
+    public void setActiveSince(Date activeSince) {
+        this.activeSince = activeSince;
+    }
+    
+    @Override
+    public int hashCode() {
+        if (hashCode != 0) return hashCode;
+        final int prime = 31;
+        hashCode = 1;
+        hashCode = prime * hashCode
+                 + ((ipv4Address == null) ? 0 : ipv4Address.hashCode());
+        hashCode = prime * hashCode + (int) (macAddress.toLong() ^ (macAddress.toLong() >>> 32));
+        hashCode = prime * hashCode + (int)switchDPID;
+        hashCode = prime * hashCode + (int)switchPort;
+        hashCode = prime * hashCode + ((vlan == null) ? 0 : vlan.hashCode());
+        return hashCode;
+    }
+
+    @Override
+    public boolean equals(Object obj) {
+        if (this == obj) return true;
+        if (obj == null) return false;
+        if (getClass() != obj.getClass()) return false;
+        OnosDevice other = (OnosDevice) obj;
+        if (hashCode() != other.hashCode()) return false;
+        if (ipv4Address == null) {
+            if (other.ipv4Address != null) return false;
+        } else if (!ipv4Address.equals(other.ipv4Address)) return false; 
+        if (macAddress == null) {
+            if (other.macAddress != null) return false;
+        } else if (!macAddress.equals(other.macAddress)) return false;
+        if(switchDPID != other.switchDPID) return false;
+        if (switchPort != other.switchPort) return false;
+        if (vlan == null) {
+            if (other.vlan != null) return false;
+        } else if (!vlan.equals(other.vlan)) return false;
+        return true;
+    }
+    
+    @Override
+    public String toString() {
+        StringBuilder builder = new StringBuilder();
+        builder.append("Entity [macAddress=");
+        builder.append(macAddress.toString());
+        builder.append(", ipv4Address=");
+        builder.append(IPv4.fromIPv4Address(ipv4Address==null ?
+                       0 : ipv4Address.intValue()));
+        builder.append(", vlan=");
+        builder.append(vlan);
+        builder.append(", switchDPID=");
+        builder.append(switchDPID);
+        builder.append(", switchPort=");
+        builder.append(switchPort);
+        builder.append(", lastSeenTimestamp=");
+        builder.append(lastSeenTimestamp == null? "null" : lastSeenTimestamp.getTime());
+        builder.append(", activeSince=");
+        builder.append(activeSince == null? "null" : activeSince.getTime());
+        builder.append("]");
+        return builder.toString();
+    }
+
+    /*
+    @Override
+    public int compareTo(OnosDevice o) {
+        if (macAddress < o.macAddress) return -1;
+        if (macAddress > o.macAddress) return 1;
+
+        int r;
+        if (switchDPID == null)
+            r = o.switchDPID == null ? 0 : -1;
+        else if (o.switchDPID == null)
+            r = 1;
+        else
+            r = switchDPID.compareTo(o.switchDPID);
+        if (r != 0) return r;
+
+        if (switchPort == null)
+            r = o.switchPort == null ? 0 : -1;
+        else if (o.switchPort == null)
+            r = 1;
+        else
+            r = switchPort.compareTo(o.switchPort);
+        if (r != 0) return r;
+
+        if (ipv4Address == null)
+            r = o.ipv4Address == null ? 0 : -1;
+        else if (o.ipv4Address == null)
+            r = 1;
+        else
+            r = ipv4Address.compareTo(o.ipv4Address);
+        if (r != 0) return r;
+
+        if (vlan == null)
+            r = o.vlan == null ? 0 : -1;
+        else if (o.vlan == null)
+            r = 1;
+        else
+            r = vlan.compareTo(o.vlan);
+        if (r != 0) return r;
+
+        return 0;
+    }*/
+    
+}