This should be a well-known fact (and it's obliquely described in IOS documentation) - if you're redistributing a default route into OSPF (for example, you have a static default route configured with ip route 0.0.0.0 0.0.0.0 ... and you use redistribute static subnets within the OSPF process), the default route will not be entered into the OSPF database unless you configure default-information originate within the router ospf configuration.
Similarly, if you configure default-information originate always, the router will inject the type 5 LSA for the default route into the OSPF topology database even if the router itself does not have a default route (or gateway of last resort).
Ivan Pepelnjak, CCIE#1354, is the chief technology advisor for NIL Data Communications. He has been designing and implementing large-scale data communications networks as well as teaching and writing books about advanced technologies since 1990. See his full profile, contact him or follow @ioshints on Twitter.
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Ivan,
ReplyDeleteWhich one is better comparing default-information originate with
default-information originate always?
Is there any scenario perhaps applicable to both commands?
thanks in advance.
If you omit always it won't inject default route if it doesn't have default route itself. Which is better? It depends on your configuration.
ReplyDeleteI've documented a few design scenarios where you might want to use one or the other.
ReplyDeleteIvan,
ReplyDeleteThank you so much. Now it's better understanding! :)