diff --git a/isisd/ChangeLog b/isisd/ChangeLog
index 33608b1..3fa9f98 100644
--- a/isisd/ChangeLog
+++ b/isisd/ChangeLog
@@ -1,3 +1,7 @@
+2004-09-14 LIU Xin <lx at ns.6test.edu.cn>
+
+	* isis_pdu.c: Update l1_desig_is only if neighbor really is DIS.
+
 2004-09-10 LIU Xin <lx at ns.6test.edu.cn>
 	
 	* isis_pdu.c: Goto out only if no adjacency exist.
diff --git a/isisd/isis_pdu.c b/isisd/isis_pdu.c
index c7142ee..1ecdab4 100644
--- a/isisd/isis_pdu.c
+++ b/isisd/isis_pdu.c
@@ -839,16 +839,18 @@
       if (memcmp (circuit->u.bc.l1_desig_is, hdr.lan_id, ISIS_SYS_ID_LEN + 1))
 	{
 	  thread_add_event (master, isis_event_dis_status_change, circuit, 0);
-	  memcpy (&circuit->u.bc.l1_desig_is, hdr.lan_id,
-		  ISIS_SYS_ID_LEN + 1);
+	  if (adj->dis_record[level-1].dis == ISIS_IS_DIS)
+	    memcpy (&circuit->u.bc.l1_desig_is, hdr.lan_id,
+		    ISIS_SYS_ID_LEN + 1);
 	}
       break;
     case 2:
       if (memcmp (circuit->u.bc.l2_desig_is, hdr.lan_id, ISIS_SYS_ID_LEN + 1))
 	{
 	  thread_add_event (master, isis_event_dis_status_change, circuit, 0);
-	  memcpy (&circuit->u.bc.l2_desig_is, hdr.lan_id,
-		  ISIS_SYS_ID_LEN + 1);
+	  if (adj->dis_record[level-1].dis == ISIS_IS_DIS)
+	    memcpy (&circuit->u.bc.l2_desig_is, hdr.lan_id,
+		    ISIS_SYS_ID_LEN + 1);
 	}
       break;
     }