diff -r 1e9383eeafb7 src/internet-stack/arp-cache.cc
--- a/src/internet-stack/arp-cache.cc	Wed May 20 15:54:56 2009 +0200
+++ b/src/internet-stack/arp-cache.cc	Thu May 21 15:58:34 2009 +0400
@@ -33,6 +33,8 @@
 
 namespace ns3 {
 
+NS_OBJECT_ENSURE_REGISTERED (ArpCache);
+
 TypeId 
 ArpCache::GetTypeId (void)
 {