From: Erick B. (erickbe@xxxxxxxxx)
Date: Fri May 18 2001 - 03:57:07 GMT-3
Hi,
The route 131.108.0.0/16 on r2 is a E2 route so it
isn't a intra-area route. This is a confusing topic
unless you go over it a few times and read over the
RFC. Section 2.3 of RFC2328 (pages 23-25) goes over
this.
Basically, external routes have a forwarding-address
(next hop) field that is set so when multiple paths
exist the external routes takes the lowest metric/cost
route to the destination network. I know this isn't
good explanation, but the RFC explains it much better
and uses an example.
Erick
--- Jaeheon Yoo <kghost@chollian.net> wrote:
> Hi, all
> According to rfc2328. p.175, when we have multiple
> intra-area paths to ASBR,
> a intra-area path using non-backbone area should be
> chosen over one using
> backbone area.
> But I always have opposite result. doesn't Cisco's
> implementation yet
> conform to rfc2328 in this respect?
>
> Here's from my cisco 2501 router.
>
> r2#sh ip ospf data
>
-------------------------------------------------omitted
> Type-5 AS External Link States
>
> Link ID ADV Router Age Seq#
> Checksum Tag
> 131.108.0.0 192.168.40.3 324
> 0x80000003 0xE930 0
> r2#
> r2#sh ip ospf border
>
> OSPF Process 10 internal Routing Table
>
> Codes: i - Intra-area route, I - Inter-area route
>
> i 192.168.40.3 [74] via 172.16.2.2, Serial0,
> ABR/ASBR, Area 0, SPF 7
> i 192.168.40.3 [1562] via 172.16.30.33, Serial1,
> ABR/ASBR, Area 6, SPF 5
>
> r2#sh ip route
> -----------------omitted
> O E2 131.108.0.0/16 [110/20] via 172.16.2.2,
> 00:03:38, Serial0
> r2#
>
> Could somebody explain this to me?
> Thanks in advance.
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