A floating static route is a backup static route. It uses an administrative distance (AD) higher than the preferred route source, so it remains out of the routing table until the primary route disappears. Lower AD values are preferred. section 17.3.2 section 17.5
Configure and verify a floating static route by following these rules:
- Set the AD at the end of the static-route command: ip route destination-network netmask next-hop ad. section 17.3.2
- Choose an AD higher than the primary route source; for OSPF, use a value greater than 110, such as 111. section 17.3.2
- Do not match the dynamic protocol’s AD: a static route with the same AD is still preferred. section 17.3.2
- Use the same principle for IPv6 by appending the backup route’s AD to the ipv6 route command. section 21.3.4
IPv6 primary and backup internet routes
R1(config)# ipv6 route ::/0 2001:db8::2 R1(config)# ipv6 route ::/0 2001:db8:1::2 2 The ISP-A route has the default AD of 1, while the ISP-B route has AD 2. R1 installs only ISP-A’s route. After G0/0 is shut down, the ISP-B floating route enters the routing table as [2/0]. section 21.3.4
