bgpd: Alow gracefull shutdown of peers

Send CEASE NOTIFICATIONS to all peers on "no router bgp"

Signed-off-by: Daniel Walton <dwalton@cumulusnetworks.com>
diff --git a/bgpd/bgpd.c b/bgpd/bgpd.c
index 7f472c5..669782d 100644
--- a/bgpd/bgpd.c
+++ b/bgpd/bgpd.c
@@ -2210,6 +2210,17 @@
 
   THREAD_OFF (bgp->t_startup);
 
+  for (ALL_LIST_ELEMENTS (bgp->peer, node, next, peer))
+    {
+      if (peer->status == Established ||
+          peer->status == OpenSent ||
+          peer->status == OpenConfirm)
+        {
+            bgp_notify_send (peer, BGP_NOTIFY_CEASE,
+                             BGP_NOTIFY_CEASE_PEER_UNCONFIG);
+        }
+    }
+
   /* Delete static route. */
   bgp_static_delete (bgp);