diff --git a/src/main/java/net/onrc/onos/core/topology/BaseInternalTopology.java b/src/main/java/net/onrc/onos/core/topology/BaseInternalTopology.java
new file mode 100644
index 0000000..6f9d9bf
--- /dev/null
+++ b/src/main/java/net/onrc/onos/core/topology/BaseInternalTopology.java
@@ -0,0 +1,133 @@
+package net.onrc.onos.core.topology;
+
+import java.util.Collection;
+
+import net.floodlightcontroller.util.MACAddress;
+import net.onrc.onos.core.util.Dpid;
+import net.onrc.onos.core.util.LinkTuple;
+import net.onrc.onos.core.util.PortNumber;
+import net.onrc.onos.core.util.SwitchPort;
+
+/**
+ * Interface to reference internal self-contained elements.
+ */
+public interface BaseInternalTopology {
+
+    /**
+     * Gets a SwitchEvent.
+     *
+     * @param dpid Switch DPID
+     * @return the SwitchEvent for the Switch DPID if found, otherwise null
+     */
+    public SwitchEvent getSwitchEvent(Dpid dpid);
+
+    /**
+     * Gets all SwitchEvent entries.
+     *
+     * @return all SwitchEvent entries.
+     */
+    public Collection<SwitchEvent> getAllSwitchEvents();
+
+    /**
+     * Gets a PortEvent.
+     *
+     * @param port Port identifier
+     * @return the PortEvent for the Port identifier if found, otherwise null
+     */
+    public PortEvent getPortEvent(SwitchPort port);
+
+    /**
+     * Gets a PortEvent.
+     *
+     * @param dpid Switch DPID
+     * @param portNumber Port number
+     * @return the PortEvent for the (Dpid, PortNumber) if found, otherwise null
+     */
+    public PortEvent getPortEvent(Dpid dpid, PortNumber portNumber);
+
+    /**
+     * Gets all the PortEvents on a switch.
+     *
+     * @param dpid Switch DPID
+     * @return PortEvents
+     */
+    public Collection<PortEvent> getPortEvents(Dpid dpid);
+
+    /**
+     * Gets all PortEvent entries.
+     *
+     * @return all PortEvent entries.
+     */
+    public Collection<PortEvent> getAllPortEvents();
+
+    /**
+     * Gets a LinkEvent.
+     *
+     * @param linkId Link identifier
+     * @return the LinkEvent for the Link identifier if found, otherwise null
+     */
+    public LinkEvent getLinkEvent(LinkTuple linkId);
+
+    /**
+     * Gets a LinkEvent.
+     *
+     * @param linkId Link identifier
+     * @param type type
+     * @return the LinkEvent for the Link identifier and type if found, otherwise null
+     */
+    public LinkEvent getLinkEvent(final LinkTuple linkId, final String type);
+
+    /**
+     * Gets all the LinkEvent departing from specified port.
+     *
+     * @param srcPort source port identifier
+     * @return Collection of LinkEvent entries
+     */
+    public Collection<LinkEvent> getLinkEventsFrom(final SwitchPort srcPort);
+
+    /**
+     * Gets all the LinkEvent pointing toward specified port.
+     *
+     * @param dstPort destination port identifier
+     * @return Collection of LinkEvent entries
+     */
+    public Collection<LinkEvent> getLinkEventsTo(final SwitchPort dstPort);
+
+    /**
+     * Gets a collection of LinkEvent entries.
+     *
+     * @param linkId Link identifier
+     * @return Collection of LinkEvent entries.
+     */
+    public Collection<LinkEvent> getLinkEvents(LinkTuple linkId);
+
+    /**
+     * Gets all LinkEvent entries.
+     *
+     * @return all LinkEvent entries.
+     */
+    public Collection<LinkEvent> getAllLinkEvents();
+
+    /**
+     * Gets a HostEvent.
+     *
+     * @param mac MACAddress of the host
+     * @return the HostEvent for the MACAddress if found, otherwise null
+     */
+    public HostEvent getHostEvent(MACAddress mac);
+
+    /**
+     * Gets all HostEvent entries attached to specified port.
+     *
+     * @param port attachment point identifier
+     * @return Collection of HostEvent entries.
+     */
+    public Collection<HostEvent> getHostEvents(SwitchPort port);
+
+    /**
+     * Gets all HostEvent entries.
+     *
+     * @return all HostEvent entries.
+     */
+    public Collection<HostEvent> getAllHostEvents();
+}