From: Paul Borghese (pborghese@groupstudy.com)
Date: Thu Jan 12 2006 - 17:18:20 GMT-3
In the older versions of the IOS code (I believe 12.1 and earlier if
memory serves me correct), NSSA routers would not automatically generate a
default route into the stub network. Thus the default-originate command
was required.
With 12.2 or late, NSSA routers behave the same as a stub and
totally-stubby ABR and automatically inject the default route.
So to answer your question, with 12.2 or later there is no benefit. With
12.1 or earlier it was necessary to inject a default route into the NSSA.
Take care,
Paul
> When configuring a NSSA with no-summary, what is the point of adding the
> default-information-originate keyword?
>
> I have tried with and without the default-information-originate keyword
> and
> both ways originate a default route.
>
> Example:
>
> R2:
> router ospf 1
> network 141.1.0.2 0.0.0.0 area 1
> area 1 nssa no-summary
>
> SW2:
>
>
> Rack1SW2#show ip route
> Codes: C - connected, S - static, R - RIP, M - mobile, B - BGP
> D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area
> N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2
> E1 - OSPF external type 1, E2 - OSPF external type 2, E - EGP
> i - IS-IS, su - IS-IS summary, L1 - IS-IS level-1, L2 - IS-IS
> level-2
> ia - IS-IS inter area, * - candidate default, U - per-user static
> route
> o - ODR, P - periodic downloaded static route
>
> Gateway of last resort is 141.1.0.2 to network 0.0.0.0
>
> 141.1.0.0/24 is subnetted, 3 subnets
> C 141.1.8.0 is directly connected, Vlan8
> C 141.1.0.0 is directly connected, Vlan258
> C 141.1.88.0 is directly connected, Vlan88
> 150.1.0.0/24 is subnetted, 1 subnets
> C 150.1.8.0 is directly connected, Loopback0
> O*IA 0.0.0.0/0 [110/2] via 141.1.0.2, 00:34:39, Vlan258
> Rack1SW2#
>
> R2:
> router ospf 1
> network 141.1.0.2 0.0.0.0 area 1
> area 1 nssa default-information-originate no-summary
>
> SW2:
>
> Rack1SW2#show ip route
> Codes: C - connected, S - static, R - RIP, M - mobile, B - BGP
> D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area
> N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2
> E1 - OSPF external type 1, E2 - OSPF external type 2, E - EGP
> i - IS-IS, su - IS-IS summary, L1 - IS-IS level-1, L2 - IS-IS
> level-2
> ia - IS-IS inter area, * - candidate default, U - per-user static
> route
> o - ODR, P - periodic downloaded static route
>
> Gateway of last resort is 141.1.0.2 to network 0.0.0.0
>
> 141.1.0.0/24 is subnetted, 3 subnets
> C 141.1.8.0 is directly connected, Vlan8
> C 141.1.0.0 is directly connected, Vlan258
> C 141.1.88.0 is directly connected, Vlan88
> 150.1.0.0/24 is subnetted, 1 subnets
> C 150.1.8.0 is directly connected, Loopback0
> O*IA 0.0.0.0/0 [110/2] via 141.1.0.2, 00:34:39, Vlan258
> Rack1SW2#
>
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