7819 IPv6 Packet and MTU bug

@@ -20,10 +20,11 @@
  */
 
 /*
  * Copyright 2010 Sun Microsystems, Inc.  All rights reserved.
  * Use is subject to license terms.
+ * Copyright 2017 OmniTI Computer Consulting, Inc. All rights reserved.
  */
 /* Copyright (c) 1990 Mentat Inc. */
 
 #include <sys/types.h>
 #include <sys/stream.h>

@@ -243,11 +244,11 @@
                     ipst->ips_ip_pathmtu_interval) {
                         /*
                          * Older than 20 minutes. Drop the path MTU information.
                          */
                         mutex_enter(&dce->dce_lock);
-                        dce->dce_flags &= ~(DCEF_PMTU|DCEF_TOO_SMALL_PMTU);
+                        dce->dce_flags &= ~DCEF_PMTU;
                         dce->dce_last_change_time = TICK_TO_SEC(now);
                         mutex_exit(&dce->dce_lock);
                         dce_increment_generation(dce);
                         ixa->ixa_fragsize = ip_get_base_mtu(nce->nce_ill, ire);
                 } else {