why doesn't ospf redistribue default routers?

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Hi, I'm playing around with OSPF, trying to get a grip of it. I've come
across an issue I don't understand.  I've got the following config.

router ospf 1
 log-adjacency-changes
 redistribute static metric 10 subnets
 network 10.5.0.6 0.0.0.0 area 0
 network 10.5.3.1 0.0.0.0 area 0

ip route 0.0.0.0 0.0.0.0 Dialer2
ip route 83.5.211.5 255.255.255.255 Dialer2

in a neighbouring table the default route is missing...

     84.0.0.0/32 is subnetted, 1 subnets
O E2    83.5.211.5 [110/10] via 10.5.0.6, 00:07:07, Serial0
     10.0.0.0/8 is variably subnetted, 5 subnets, 3 masks
C       10.5.0.4/30 is directly connected, Serial0
O       10.5.3.0/24 [110/161] via 10.5.0.6, 00:07:08, Serial0
C       10.5.2.0/24 is directly connected, Loopback0
O       10.5.1.1/32 [110/65] via 10.5.0.1, 00:20:20, Serial1
C       10.5.0.0/30 is directly connected, Serial1

I would expect both those static routes to be propogated across the domain
as O E2 types, but only the bottom one of the two routes get passed on.
Could anyone explain to me why the default route doesn't?

thanks.




Re: why doesn't ospf redistribue default routers?


Source : "Cisco Cookbook" (O'Reilly)
You cannot create a default route in OSPF by simply redistributing a static
route as with RIP and EIGRP.
Even if there is a default route in the routing table, it will not be
forwarded by default. This is because OSPF uses link state algorithm that
keeps track of links rather than routes.
You must explicitely tell OSPF you want to source the default route with the
"default-information originate" command.
Therefore you may want to issue on the gateway:

(config)#router ospf 1
(config-router)#default-information originate metric 10
(config-router)#end

Bernard.

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Re: why doesn't ospf redistribue default routers?


Thanks Bernard that worked, well explained, thanks.

eeee byeee gum youre a clever lad!

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