Found question 2 answer in the RFC 1587 :
"If the destination is the default route (destination =
DefaultDestination) and if the originator of the LSA and
the calculating router are both NSSA area border routers
do nothing with this LSA and consider the next in the list."
""Stephane LITKOWSKI"" a icrit dans le message de news:
[EMAIL PROTECTED]
> For the first problem, I can see in routing table the concept of Forward
> metric, if bandwidth are unequal, first route has :
>
> IR_AS200_AREA1#sh ip route 0.0.0.0
> Routing entry for 0.0.0.0/0, supernet
> Known via "ospf 1", distance 110, metric 100, candidate default path,
type
> NSS
> A extern 2, forward metric 10
> Redistributing via ospf 1
> Last update from 193.0.0.2 on Ethernet0, 00:00:00 ago
> Routing Descriptor Blocks:
> * 193.0.0.2, from 192.168.108.2, 00:00:00 ago, via Ethernet0
> Route metric is 100, traffic share count is 1
>
> If I shut down the ethernet link, the second route goes up :
>
> IR_AS200_AREA1#sh ip route 0.0.0.0
> Routing entry for 0.0.0.0/0, supernet
> Known via "ospf 1", distance 110, metric 100, candidate default path,
type
> NSS
> A extern 2, forward metric 64
> Redistributing via ospf 1
> Last update from 2.0.0.1 on Serial0, 00:00:00 ago
> Routing Descriptor Blocks:
> * 2.0.0.1, from 192.168.108.4, 00:00:00 ago, via Serial0
> Route metric is 100, traffic share count is 1
>
> Does the concept of forward metric influence the choose of routes for NSSA
?
>
> ""Stephane LITKOWSKI"" a icrit dans le message de news:
> [EMAIL PROTECTED]
> > Hi all,
> >
> > I have some questions about Type 7 LSA default-routes propagated by
ABRs.
> > Consider a NSSA with two ABRs. Each ABR propagate a default route with a
> > cost of 100 (commands are : area 1 nssa default-originate & area 1
> > default-cost 100).
> > On a Internal router directly connected to each ABR, I can see that only
> one
> > default route is in the routing table :
> >
> > O*N2 0.0.0.0/0 [110/100] via 193.0.0.2, Ethernet0
> >
> > But the two LSA are in the database :
> >
> > IR_AS200_AREA1#sh ip ospf database nssa-external
> >
> > OSPF Router with ID (192.168.108.3) (Process ID 1)
> >
> >
> > Type-7 AS External Link States (Area 1)
> >
> > Routing Bit Set on this LSA
> > LS age: 1702
> > Options: (No TOS-capability, No Type 7/5 translation, DC)
> > LS Type: AS External Link
> > Link State ID: 0.0.0.0 (External Network Number )
> > Advertising Router: 192.168.108.2
> > LS Seq Number: 80000001
> > Checksum: 0x4F63
> > Length: 36
> > Network Mask: /0
> > Metric Type: 2 (Larger than any link state path)
> > TOS: 0
> > Metric: 100
> > Forward Address: 193.0.0.2
> > External Route Tag: 0
> >
> > LS age: 318
> > Options: (No TOS-capability, No Type 7/5 translation, DC)
> > LS Type: AS External Link
> > Link State ID: 0.0.0.0 (External Network Number )
> > Advertising Router: 192.168.108.4
> > LS Seq Number: 80000003
> > Checksum: 0xF37B
> > Length: 36
> > Network Mask: /0
> > Metric Type: 2 (Larger than any link state path)
> > TOS: 0
> > Metric: 100
> > Forward Address: 2.0.0.1
> > External Route Tag: 0
> >
> > My first question is, why does the IR choose one default route and not
the
> > both ? With more investigation, I can see that it prefer the link with
the
> > highest bandwidth. If I increase the bandwidth of the other link, the
> > nexthop change :
> >
> > O*N2 0.0.0.0/0 [110/100] via 2.0.0.1, Serial0
> >
> > if bandwidth are equal, the both routes are introduced :
> >
> > O*N2 0.0.0.0/0 [110/100] via 193.0.0.2, Ethernet0
> > [110/100] via 2.0.0.1, Serial0
> >
> > Why does it consider cost of the link ?
> >
> > My other question is, on the ABR. I can see that the 0.0.0.0 LSA are in
> the
> > database. The First one is not computed because selforiginated but why
the
> > other is not computed ? (It's a type 7 LSA , not type 3).
> >
> >
> > Thanks for help.
> >
> > --
> > Stephane LITKOWSKI
> > Student in a French computer science school
> > EPITA Telecom & Network specialization (Paris, FRANCE)
> > CCNA + CCNP
> > EMail : [EMAIL PROTECTED]
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