why doesn't ospf redistribue default routers?

Have a question or want to start a discussion? Post it! No Registration Necessary.  Now with pictures!

Threaded View

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
 redistribute static metric 10 subnets
 network area 0
 network area 0

ip route Dialer2
ip route Dialer2

in a neighbouring table the default route is missing... is subnetted, 1 subnets
O E2 [110/10] via, 00:07:07, Serial0 is variably subnetted, 5 subnets, 3 masks
C is directly connected, Serial0
O [110/161] via, 00:07:08, Serial0
C is directly connected, Loopback0
O [110/65] via, 00:20:20, Serial1
C 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?


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


Quoted text here. Click to load it

Re: why doesn't ospf redistribue default routers?

Thanks Bernard that worked, well explained, thanks.

eeee byeee gum youre a clever lad!

Quoted text here. Click to load it

Site Timeline