The OSPF default mysteries
A while ago I wanted to combine the blog posts I've written about the default routes in OSPF into a single wiki article. As I started to investigate the various options you have to generate default routing in OSPF (including stub areas and not-so-stubby areas), the text quickly became too long and resulted in July IP Corner article "The OSPF default mysteries".
4 comments:
It's always very interesting to ready your IPConer articles.
Its so comprehensive.
It's pity that these articles appeared only monthly :)
A brilliant review of a subject which is rarely found discussed in its entirety. Nicely done!
this line: The default route is originated only when a major network is matched (tested in IOS release 12.2SRC). You cannot originate a default route based on the presence of a subnet or a supernet.
Can i not match on a network in my BGP table, to tell if BGP is up (and working)?
i tried this:
+ ip access-list standard GOOGLE
+ permit 72.14.192.0
+ !
+ route-map GOOGLE permit 10
+ match ip address GOOGLE
+ !
+ default-information originate always metric 10 route-map GOOGLE
and OSPF won't default-originate (though of course that network is in the table (twice!)).
As I wrote (and you quoted): The default route is originated only when a major network is matched. 72.14.192.0/24 is not a major network, 72.0.0.0/8 is.
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