--- a/src/node/ipv4-l4-protocol.h	Sun Mar 18 19:31:32 2007 +0100
+++ b/src/node/ipv4-l4-protocol.h	Sun Mar 18 14:06:51 2007 -0700
@@ -31,6 +31,8 @@
 class Node;
 class Packet;
 class Ipv4Address;
+class TraceResolver;
+class TraceContext;
   
 class Ipv4L4Protocol {
 public:
@@ -41,6 +43,7 @@
   int GetVersion() const;
 
   virtual Ipv4L4Protocol* Copy(Node *node) const = 0;
+  virtual TraceResolver *CreateTraceResolver (TraceContext const &context) = 0;
   /**
    * Called from lower-level layers to send the packet up
    * in the stack.