OSPF reliable conditional default routing lab
Lab in question:
My question is: How is R8 advertising a default route, if the default-information originate always key-word isn't used?
When I attempted this lab, I simply created a default route to null0 and put the track there. In this case, the router has a default route when the track is up, and advertises the default. When the default is gone (track down) then it retracts the advertised default.
With the lab, how would this work?
Comments
whats your config looks like? there is exception to always rule; I think if u have route map with default info originate, always keyword is ignored.
So after digging around and conversing with my study group, it appears as if this is a good source of information:
http://packetlife.net/blog/2008/dec/12/ospf-conditional-default-route-injection/
The default will be advertised in 3 possible ways:
1) If we use default-information originate WITH a default route in the RIB.
2) If we use default-information originate always WITH/WITHOUT a default route in the RIB.
3) If we use default-information originate WITH a conditional route-map.
There are technically 3 ways to originate a default route via the "default-information originate" in OSPF.
1. Use the always key
2. Already have a 0/0 route in the RIB from whatever else
3. Tie the origination condition to a junk route you create on your own. In this case, they are injecting 169.254.0.1 route into the RIB via static with an SLA track to make it conditional. Then tieing that to the ospf originate command via the route-map. So if 169.254.0.1 is in, ospf will originate, if the SLA drops, the route gets removed, ospf pulls it's default originate.
in your case #3, always keyword will be ignored. right? lab it please.