High Availability and Virtualization Features in the JUNOS Software

In support of high-availability router functioning, the JUNOS Software includes the following features:

• Graceful restart—Enables a routing protocol, before it restarts, to inform its adjacent neighbors and peers of its condition. Protocol Independent Multicast (PIM) in sparse mode and most other JUNOS routing protocols support graceful restart.
• Graceful Routing Engine switchover—On routers with dual Routing Engines, enables switching of mastership between Routing Engines without interruption to packet forwarding.

  For routers in which Adaptive Services (AS) PICs are installed, features that use adaptive services are interrupted momentarily during a Routing Engine switchover. Features that do not use adaptive services continue uninterrupted. After switchover, all features are restored and packet forwarding continues. Note, however, that Layer 2 Tunneling Protocol (L2TP) does not come up after a graceful switchover.

The JUNOS Software supports unicast reverse-path forwarding.

The JUNOS Software supports routing instances, which enables you to create multiple instances of BGP, IS-IS, OSPF, PIM, RIP, and static routes.

The JUNOS Software supports logical systems, which enables you to create multiple logical routing devices within a single router.