High availability features include Routing Engine redundancy,
graceful Routing Engine switchover (GRES), nonstop bridging, nonstop
active routing, graceful restart for routing protocols, Virtual Router
Redundancy Protocol (VRRP), and unified in-service software upgrade
(ISSU). Some high availability features are not supported by all platforms
and all PICs. For more information, see the Junos OS High Availability Configuration Guide
.