diff -abur --exclude-from=exclude_files ospfd1.6/src/config.C ospfd1.7/src/config.C
--- ospfd1.6/src/config.C	Tue May 30 17:00:51 2000
+++ ospfd1.7/src/config.C	Fri Jun  2 11:25:15 2000
@@ -70,17 +70,22 @@
  * Those configuration items that have not been
  * updated are either deleted or returned to their
  * default values.
+ * We have to be a little careful traversing the list
+ * of configured items because the removal of one
+ * item by ConfigItem::clear_config() may cause
+ * other items to get deleted further down the list.
  */
 
 void OSPF::cfgDone()
 
 {
+    ConfigItem **prev;
     ConfigItem *item;
-    ConfigItem *next;
 
-    for (item = cfglist; item; item = next) {
-	next = item->next;
+    for (prev = &cfglist; (item = *prev); ) {
 	if (!item->updated)
 	    item->clear_config();
+	if (item == *prev)
+	    prev = &item->next;
     }
 }
diff -abur --exclude-from=exclude_files ospfd1.6/src/spfifc.C ospfd1.7/src/spfifc.C
--- ospfd1.6/src/spfifc.C	Tue May 30 17:00:51 2000
+++ ospfd1.7/src/spfifc.C	Fri Jun  2 11:25:15 2000
@@ -214,6 +214,10 @@
     area_flood = false;
     global_flood = false;
     if_demand_helapse = 0;
+    // Virtual link parameters
+    if_tap = 0;		// Transit area
+    if_nbrid = 0;	// Configured neighbor ID
+    if_rmtaddr = 0;	// IP address of other end
 }
 
 /* Destructor for an interface. Declare the interface down,
@@ -289,26 +293,38 @@
     return("Unknown");
 }
 
-/* Base functions that may be overriden for specific interface
- * types.
- */
+// Is the interface a virtual link?
 
 bool SpfIfc::is_virtual()
 {
-    return(false);
+    return(if_type == IFT_VL);
 }
+
+// Can the interface support more than one neighbor?
+
 bool SpfIfc::is_multi_access()
 {
-    return(true);
+    return(if_type != IFT_PP && if_type != IFT_VL);
 }
+
+// Return the transit area (0 if not a virtual link)
+
 SpfArea *SpfIfc::transit_area()
 {
-    return(0);
+    return(if_tap);
 }
+
+// Return the endpoint of a virtual link
+
 rtid_t *SpfIfc::vl_endpt()
 {
-    return(0);
+    return(&if_nbrid);
 }
+
+/* Base functions that may be overriden for specific interface
+ * types.
+ */
+
 void SpfIfc::start_hellos()
 {
     send_hello();
@@ -328,30 +344,8 @@
     return(false);
 }
 
-/* Trivial virtual functions for point-to-point interfaces.
- */
-
-bool PPIfc::is_multi_access()
-{
-    return(false);
-}
-
 /* Trivial virtual functions for virtual links.
  */
-
-SpfArea *VLIfc::transit_area()
-{
-    return(if_tap);
-}
-bool VLIfc::is_virtual()
-{
-    return(true);
-}
-
-rtid_t *VLIfc::vl_endpt()
-{
-    return(&if_nbrid);
-}
 
 /* Trivial functions for interfaces which elect a Designated
  * Router.
diff -abur --exclude-from=exclude_files ospfd1.6/src/spfifc.h ospfd1.7/src/spfifc.h
--- ospfd1.6/src/spfifc.h	Tue May 30 17:00:51 2000
+++ ospfd1.7/src/spfifc.h	Fri Jun  2 11:25:15 2000
@@ -157,6 +157,11 @@
     void ifa_reset();
     void ifa_allnbrs_event(int event);
 
+    // Virtual link parameters
+    SpfArea *if_tap;	// Transit area
+    rtid_t if_nbrid;	// Configured neighbor ID
+    InAddr if_rmtaddr;	// IP address of other end
+
   public:
     // Configurable parameters
     InAddr if_addr;	// Interface IP address
@@ -203,6 +208,10 @@
     void reorig_all_grplsas();
     int type();
     void run_fsm(int event);// Interface Finite state machine
+    bool is_virtual();
+    bool is_multi_access();
+    SpfArea *transit_area();
+    rtid_t *vl_endpt();
 
     // Virtual functions
     virtual void clear_config();
@@ -215,10 +224,6 @@
     virtual void add_adj_to_cand(class PriQ &cand) = 0;
     virtual int adjacency_wanted(class SpfNbr *np);
     virtual void send_hello_response(SpfNbr *np);
-    virtual bool is_virtual();
-    virtual bool is_multi_access();
-    virtual SpfArea *transit_area();
-    virtual rtid_t *vl_endpt();
     virtual void start_hellos();
     virtual void restart_hellos();
     virtual void stop_hellos();
@@ -309,7 +314,6 @@
 class PPIfc : public SpfIfc {
   public:
     inline PPIfc(InAddr addr, int phyint);
-    bool is_multi_access();
     virtual void ifa_start();
     virtual class SpfNbr *find_nbr(InAddr, rtid_t);
     virtual void set_id_or_addr(SpfNbr *, rtid_t, InAddr);
@@ -332,15 +336,9 @@
  */
 
 class VLIfc : public PPIfc {
-    SpfArea *if_tap;	// Transit area
-    rtid_t if_nbrid;	// Configured neighbor ID
-    InAddr if_rmtaddr;	// IP address of other end
   public:
     VLIfc(SpfArea *, class RTRrte *);
     ~VLIfc();
-    virtual SpfArea *transit_area();
-    virtual rtid_t *vl_endpt();
-    virtual bool is_virtual();
     virtual void ifa_start();
     virtual void if_send(Pkt *, InAddr);
     virtual void nbr_send(Pkt *, SpfNbr *);

.