Junos Enterprise Routing, 2nd Edition

Protocol Independent Properties

PIPs are used for a variety of functions, such as static and aggregate routes, protocol preferences, route tables, router ID, and so forth. The range of PIPs is configured at the [edit routing-options] hierarchy.

Static, Aggregate, and Generated Routes

Although the use of static routing is sometimes considered bad form, especially during a routing-protocol-based practical examination, there are many practical applications for static routes, along with their aggregate/generated counterparts.

Static routing suffers from a general lack of dynamism (though Bidirectional Forwarding Detection [BFD] can mitigate this issue), which often leads to loss of connectivity during network outages due to the inability to reroute. Static routes can quickly become maintenance and administration burdens for networks that have frequent adds, moves, or changes. With that said, static routing is often used at the network edge to support attachment to stub networks, which, given their single point of entry/egress, are well suited to the simplicity of a static route.

Static routes are often used to promote stability through advertisement into a routing protocol, such as BGP, where a single route that is always up is used to represent the connectivity of numerous, more specific routes, which individually may come and go (flap) because of instability in the attached network’s infrastructure. By suppressing the specifics in favor of a single static route, the world is shielded ...