diff --git a/src/main/java/net/onrc/onos/core/topology/SwitchImpl.java b/src/main/java/net/onrc/onos/core/topology/SwitchImpl.java
new file mode 100644
index 0000000..8a45b76
--- /dev/null
+++ b/src/main/java/net/onrc/onos/core/topology/SwitchImpl.java
@@ -0,0 +1,122 @@
+package net.onrc.onos.core.topology;
+
+import java.util.ArrayList;
+import java.util.Collection;
+import java.util.Collections;
+import java.util.HashMap;
+import java.util.HashSet;
+import java.util.LinkedList;
+import java.util.List;
+import java.util.Map;
+import java.util.Set;
+
+/**
+ * Switch Object stored in In-memory Topology.
+ *
+ * TODO REMOVE following design memo: This object itself may hold the DBObject,
+ * but this Object itself will not issue any read/write to the DataStore.
+ */
+public class SwitchImpl extends NetworkGraphObject implements Switch {
+
+	private Long dpid;
+	// These needs to be ConcurrentCollecton if allowing Graph to be accessed Concurrently
+	private final Map<Long, Port> ports;
+
+	public SwitchImpl(NetworkGraph graph, Long dpid) {
+		super(graph);
+		this.dpid = dpid;
+		ports = new HashMap<Long, Port>();
+	}
+
+	@Override
+	public Long getDpid() {
+		return dpid;
+	}
+
+	@Override
+	public Collection<Port> getPorts() {
+		return Collections.unmodifiableCollection(ports.values());
+	}
+
+	@Override
+	public Port getPort(Long number) {
+		return ports.get(number);
+	}
+
+	@Override
+	public Iterable<Switch> getNeighbors() {
+		Set<Switch> neighbors = new HashSet<>();
+		for (Link link : getOutgoingLinks()) {
+		    neighbors.add(link.getDstSwitch());
+		}
+		// XXX should incoming considered neighbor?
+		for (Link link : getIncomingLinks()) {
+		    neighbors.add(link.getSrcSwitch());
+		}
+		return neighbors;
+	}
+
+	@Override
+	public Link getLinkToNeighbor(Long neighborDpid) {
+		for (Link link : getOutgoingLinks()) {
+			if (link.getDstSwitch().getDpid().equals(neighborDpid) ) {
+				return link;
+			}
+		}
+		return null;
+	}
+
+	@Override
+	public Collection<Device> getDevices() {
+		// TODO Should switch also store a list of attached devices to avoid
+		// calculating this every time?
+		List<Device> devices = new ArrayList<Device>();
+
+		for (Port port : ports.values()) {
+			for (Device device : port.getDevices()) {
+				devices.add(device);
+			}
+		}
+
+		return devices;
+	}
+
+	public void addPort(Port port) {
+		this.ports.put(port.getNumber(), port);
+	}
+
+	public Port removePort(Port port) {
+	    Port p = this.ports.remove(port.getNumber());
+	    return p;
+	}
+
+	public Port addPort(Long portNumber) {
+		PortImpl port = new PortImpl(graph, this, portNumber);
+		ports.put(port.getNumber(), port);
+		return port;
+	}
+
+	@Override
+	public Iterable<Link> getOutgoingLinks() {
+		LinkedList<Link> links = new LinkedList<Link>();
+		for (Port port: getPorts()) {
+			Link link = port.getOutgoingLink();
+			if (link != null) {
+				links.add(link);
+			}
+		}
+		return links;
+	}
+
+	@Override
+	public Iterable<Link> getIncomingLinks() {
+		LinkedList<Link> links = new LinkedList<Link>();
+		for (Port port: getPorts()) {
+			Link link = port.getIncomingLink();
+			if (link != null) {
+				links.add(link);
+			}
+		}
+		return links;
+	}
+}