1. when We redistribute from ospf 2 to ospf 1, if ospf 2 has
default-route, all network from ospf 2 to ospf 1 but except
default-route Right?
Correct.
2. If we would like to perform that ospf 2 has just only default route
toward ospf 1, just only configure 'default-information originate' on
boundary router?
Correct. Caveat, you must have a 0.0.0.0 in the RIB for the default-information originate to work. If you have default-information originate always, then a default route will be provided even if you had no 0.0.0.0 in the RIB.
. I would like to know the exact knowledge, the difference of between
redi. default-route and default-information originate.
You can't redistribute the default route in OSPF, the only way is to issue a default-information originate and I explained above, there is a 'always' keyword.
4. On some device, I check that when I redistribute default-route on that, the default-route was advertised to all same ospf process.
but, on other device, redi. default-route didn't work, So We have to use 'default-information originate',
Is it related 'IOS'
That's not an expected behavior and I will love to see the config outputs. You can't redistribute the default into OSPF.
Regards,
Edison