diff --git a/web/gui/src/main/java/org/onosproject/ui/impl/topo/BiLink.java b/web/gui/src/main/java/org/onosproject/ui/impl/topo/BiLink.java
index 5ab4e0e..8ccf543 100644
--- a/web/gui/src/main/java/org/onosproject/ui/impl/topo/BiLink.java
+++ b/web/gui/src/main/java/org/onosproject/ui/impl/topo/BiLink.java
@@ -19,226 +19,87 @@
 
 import org.onosproject.net.Link;
 import org.onosproject.net.LinkKey;
-import org.onosproject.net.statistic.Load;
 import org.onosproject.ui.topo.LinkHighlight;
 
-import static org.onosproject.ui.topo.LinkHighlight.Flavor.NO_HIGHLIGHT;
-import static org.onosproject.ui.topo.LinkHighlight.Flavor.PRIMARY_HIGHLIGHT;
-import static org.onosproject.ui.topo.LinkHighlight.Flavor.SECONDARY_HIGHLIGHT;
+import static com.google.common.base.Preconditions.checkNotNull;
 
 /**
- * Representation of a link and its inverse, and any associated traffic data.
- * This class understands how to generate {@link LinkHighlight}s for sending
- * back to the topology view.
+ * Representation of a link and its inverse, as a partial implementation.
+ * <p>
+ * Subclasses will decide how to generate the link highlighting (coloring
+ * and labeling) for the topology view.
  */
-public class BiLink {
-
-    private static final String EMPTY = "";
+public abstract class BiLink {
 
     private final LinkKey key;
     private final Link one;
     private Link two;
 
-    private boolean hasTraffic = false;
-    private long bytes = 0;
-    private long rate = 0;
-    private long flows = 0;
-    private boolean isOptical = false;
-    private LinkHighlight.Flavor taggedFlavor = NO_HIGHLIGHT;
-    private boolean antMarch = false;
-
     /**
-     * Constructs a bilink for the given key and initial link.
+     * Constructs a bi-link for the given key and initial link. It is expected
+     * that the caller will have used {@link TopoUtils#canonicalLinkKey(Link)}
+     * to generate the key.
      *
-     * @param key canonical key for this bilink
+     * @param key canonical key for this bi-link
      * @param link first link
      */
     public BiLink(LinkKey key, Link link) {
-        this.key = key;
-        this.one = link;
+        this.key = checkNotNull(key);
+        this.one = checkNotNull(link);
     }
 
     /**
-     * Sets the second link for this bilink.
+     * Sets the second link for this bi-link.
      *
      * @param link second link
      */
     public void setOther(Link link) {
-        this.two = link;
+        this.two = checkNotNull(link);
     }
 
     /**
-     * Sets the optical flag to the given value.
+     * Returns the link identifier in the form expected on the Topology View
+     * in the web client.
      *
-     * @param b true if an optical link
+     * @return link identifier
      */
-    public void setOptical(boolean b) {
-        isOptical = b;
-    }
-
-    /**
-     * Sets the ant march flag to the given value.
-     *
-     * @param b true if marching ants required
-     */
-    public void setAntMarch(boolean b) {
-        antMarch = b;
-    }
-
-    /**
-     * Tags this bilink with a link flavor to be used in visual rendering.
-     *
-     * @param flavor the flavor to tag
-     */
-    public void tagFlavor(LinkHighlight.Flavor flavor) {
-        this.taggedFlavor = flavor;
-    }
-
-    /**
-     * Adds load statistics, marks the bilink as having traffic.
-     *
-     * @param load load to add
-     */
-    public void addLoad(Load load) {
-        addLoad(load, 0);
-    }
-
-    /**
-     * Adds load statistics, marks the bilink as having traffic, if the
-     * load rate is greater than the given threshold.
-     *
-     * @param load load to add
-     * @param threshold threshold to register traffic
-     */
-    public void addLoad(Load load, double threshold) {
-        if (load != null) {
-            this.hasTraffic = hasTraffic || load.rate() > threshold;
-            this.bytes += load.latest();
-            this.rate += load.rate();
-        }
-    }
-
-    /**
-     * Adds the given count of flows to this bilink.
-     *
-     * @param count count of flows
-     */
-    public void addFlows(int count) {
-        this.flows += count;
-    }
-
-    /**
-     * Generates a link highlight entity, based on state of this bilink.
-     *
-     * @param type the type of statistics to use to interpret the data
-     * @return link highlight data for this bilink
-     */
-    public LinkHighlight generateHighlight(LinkStatsType type) {
-        switch (type) {
-            case FLOW_COUNT:
-                return highlightForFlowCount(type);
-
-            case FLOW_STATS:
-            case PORT_STATS:
-                return highlightForStats(type);
-
-            case TAGGED:
-                return highlightForTagging(type);
-
-            default:
-                throw new IllegalStateException("unexpected case: " + type);
-        }
-    }
-
-    private LinkHighlight highlightForStats(LinkStatsType type) {
-        return new LinkHighlight(linkId(), SECONDARY_HIGHLIGHT)
-                .setLabel(generateLabel(type));
-    }
-
-    private LinkHighlight highlightForFlowCount(LinkStatsType type) {
-        LinkHighlight.Flavor flavor = flows() > 0 ?
-                PRIMARY_HIGHLIGHT : SECONDARY_HIGHLIGHT;
-        return new LinkHighlight(linkId(), flavor)
-                .setLabel(generateLabel(type));
-    }
-
-    private LinkHighlight highlightForTagging(LinkStatsType type) {
-        LinkHighlight hlite = new LinkHighlight(linkId(), flavor())
-                .setLabel(generateLabel(type));
-        if (isOptical()) {
-            hlite.addMod(LinkHighlight.MOD_OPTICAL);
-        }
-        if (isAntMarch()) {
-            hlite.addMod(LinkHighlight.MOD_ANIMATED);
-        }
-        return hlite;
-    }
-
-    // Generates a link identifier in the form that the Topology View on the
-    private String linkId() {
+    public String linkId() {
         return TopoUtils.compactLinkString(one);
     }
 
-    // Generates a string representation of the load, to be used as a label
-    private String generateLabel(LinkStatsType type) {
-        switch (type) {
-            case FLOW_COUNT:
-                return TopoUtils.formatFlows(flows());
-
-            case FLOW_STATS:
-                return TopoUtils.formatBytes(bytes());
-
-            case PORT_STATS:
-                return TopoUtils.formatBitRate(rate());
-
-            case TAGGED:
-                return hasTraffic() ? TopoUtils.formatBytes(bytes()) : EMPTY;
-
-            default:
-                return "?";
-        }
-    }
-
-    // === ----------------------------------------------------------------
-    // accessors
-
+    /**
+     * Returns the key for this bi-link.
+     *
+     * @return the key
+     */
     public LinkKey key() {
         return key;
     }
 
+    /**
+     * Returns the first link in this bi-link.
+     *
+     * @return the first link
+     */
     public Link one() {
         return one;
     }
 
+    /**
+     * Returns the second link in this bi-link.
+     *
+     * @return the second link
+     */
     public Link two() {
         return two;
     }
 
-    public boolean hasTraffic() {
-        return hasTraffic;
-    }
-
-    public boolean isOptical() {
-        return isOptical;
-    }
-
-    public boolean isAntMarch() {
-        return antMarch;
-    }
-
-    public LinkHighlight.Flavor flavor() {
-        return taggedFlavor;
-    }
-
-    public long bytes() {
-        return bytes;
-    }
-
-    public long rate() {
-        return rate;
-    }
-
-    public long flows() {
-        return flows;
-    }
+    /**
+     * Returns the link highlighting to use, based on this bi-link's current
+     * state.
+     *
+     * @param type optional highlighting type parameter
+     * @return link highlighting model
+     */
+    public abstract LinkHighlight highlight(Enum<?> type);
 }