Lesson 36: Floating Static Routes

A Floating Static Route is a static route configured with an Administrative Distance (AD) higher than the primary route. This makes the static route less trustworthy than the dynamic or main static route.

Purpose of Floating Static Routes

They provide a backup path. If the primary route (e.g., OSPF, AD 110) fails, it is removed from the routing table. The floating static route (e.g., AD 120) is then installed, allowing traffic to failover to a secondary path.

Configuration Example

Assume the primary route to the Internet is via OSPF (AD 110).

1. Primary Route (Dynamic): Learned via OSPF (AD 110).

2. Backup Route (Floating Static): We define a default route pointing to a backup link, assigning it a high AD (e.g., 150).

ios ! Primary path fails, router installs this backup route Router(config)# ip route 0.0.0.0 0.0.0.0 10.1.1.2 150

The route with AD 150 remains dormant (floating) in the configuration until the primary route disappears from the routing table.