12-11-2009 02:05 AM - edited 03-06-2019 08:55 AM
I have a small question about floating static routes, how does the route know when the next hop has gone down and to use the next route with higher AD ? does it use some simple icmp checks ?
Solved! Go to Solution.
12-11-2009 02:15 AM
Hello Carl,
without object tracking the router will consider the IP next-hop reachable until the interface where the IP subnet of the next-hop is up.
In case of LAN switched environment, the L3 interface can be an SVI and the next-hop can die without L3 interface to fail too.
In this case the next-hop is considered valid until the associated ARP entry is valid up to 4 hours on a cisco device with default settings.
In a LAN environment : or move to dynamic routing or you need to use reliable static routing
see
http://www.cisco.com/en/US/docs/ios/12_3/12_3x/12_3xe/feature/guide/dbackupx.html
the primary static route next-hop has to be tracked using an tracking object or an IP SLA (IOS version dependent)
when the tracked object / IP SLA fails the primary route is removed from IP routing table and secondary route (with higher AD) is installed.
Hope to help
Giuseppe
12-11-2009 02:15 AM
Hello Carl,
without object tracking the router will consider the IP next-hop reachable until the interface where the IP subnet of the next-hop is up.
In case of LAN switched environment, the L3 interface can be an SVI and the next-hop can die without L3 interface to fail too.
In this case the next-hop is considered valid until the associated ARP entry is valid up to 4 hours on a cisco device with default settings.
In a LAN environment : or move to dynamic routing or you need to use reliable static routing
see
http://www.cisco.com/en/US/docs/ios/12_3/12_3x/12_3xe/feature/guide/dbackupx.html
the primary static route next-hop has to be tracked using an tracking object or an IP SLA (IOS version dependent)
when the tracked object / IP SLA fails the primary route is removed from IP routing table and secondary route (with higher AD) is installed.
Hope to help
Giuseppe
Discover and save your favorite ideas. Come back to expert answers, step-by-step guides, recent topics, and more.
New here? Get started with these tips. How to use Community New member guide