why doesn't ospf redistribue default routers?

Question

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.

Stuart Wilcox · Accepted Answer

Thanks Bernard that worked, well explained, thanks.eeee byeee gum youre a clever lad!

Bernard Herickx · Answer

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)#endBernard.

why doesn't ospf redistribue default routers?

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