Conditional static route - what's the term...?

jwilson1 · ‎04-02-2008

What is the term to use when you have a static route that is dependent on the availability of the next hop? For instance, if you have "ip route 1.2.3.4 255.255.255.255 2.3.4.5" and that route is dependent on 2.3.4.5 being in the routing table. I thought it was "conditional static route", and I tried looking this up but only found information on object tracking, etc. This is only for documentation purposes. Thanks in advance!

paolo bevilacqua · ‎04-02-2008

Hi, that is a regular static route, is installed only when NH or interface is available.

Perhaps you meant floating static, that also specifies a metric of "administrative distance", that kind conditionally kicks in only when no route of better AD is available.

Technically they are the same thing, only the "non-floating" has an implicit AD of 0.

Hope this helps, please rate post if it does!

jwilson1 · ‎04-02-2008

I didn't mean floating static, but when you put it that way, I guess it could be considered a floating static with a distance of 1, which floats above zero other routes. =) I somehow thought there was another term for what I was describing.

sundar.palaniappan · ‎04-02-2008

I believe the term you are looking for is Reliable Static Routing backup using object tracking. As Paolo stated it's used in situations where you want a floating static route, route w/higher administrative distance, to be used when the tracked object for the primary route goes away. The tracked object do not have to be the next hop itself and it can be any IP address.

http://www.cisco.com/en/US/docs/ios/12_3/12_3x/12_3xe/feature/guide/dbackupx.html

There's another flavor for the same functionality and it verifies the next-hop availability before forwarding traffic to the next hop and it's configured with route maps and rtr or IP SLA command. I don't know if you have this feature in mind. But, here's a link for that one.

http://www.cisco.com/en/US/tech/tk364/technologies_configuration_example09186a0080211f5c.shtml

HTH

Sundar