From: Simon Baxter (Simon.Baxter@xxxxxxxxxxxxxx)
Date: Mon Dec 04 2000 - 01:30:56 GMT-3
This I don't understand.
I understand that intra are preferred over inter-area, but as I illustrated,
the only thing I changed was to make area1 a transit area for a VL to area
2. Why would the 10.0.x.x network, being in area0, now become INTRA-area??
Yikes....
1 week to go!
-----Original Message-----
From: Brian Hescock [mailto:bhescock@cisco.com]
Sent: Monday, December 04, 2000 2:30 PM
To: Simon Baxter
Cc: CCIE Group Study (E-mail)
Subject: Re: OSPF Virtual links stuff up routing...
Simon,
Notice that one is an inter-area route (IA) and the other is an
intra-area route (O). OSPF is preferring the intra-area route as it
should.
Brian
On Mon, 4 Dec 2000, Simon Baxter wrote:
> I've discovered Virtual Links seem to prefer a path through some networks
-
> against the metric of transiting links....
>
> In the below example, a slow speed 64k serial link is preferred over a
10Meg
> connection - because of the Virtual link.....
>
>
> Scenario is - "BOTTOM" is in area 1 and has 2 connections to area 0: via
> s0/0(toR5) and via e0/0(via R2)
>
> Without any VLs configured, the preferred path to area 0 is via the
> ethernet...
>
> (10.0.10.3 is another device in area 0)
>
> BOTTOM#sh ip ro
> Codes: C - connected, S - static, I - IGRP, 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, 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 not set
>
> 192.192.192.0/32 is subnetted, 1 subnets
> O IA 192.192.192.192 [110/21] via 10.1.2.1, 00:05:15, Ethernet0/0
> 10.0.0.0/24 is subnetted, 4 subnets
> O IA 10.0.10.0 [110/20] via 10.1.2.1, 00:05:15, Ethernet0/0
> O IA 10.3.0.0 [110/68] via 10.1.2.1, 00:05:15, Ethernet0/0
> C 10.1.2.0 is directly connected, Ethernet0/0
> C 10.1.1.0 is directly connected, Serial0/0
> BOTTOM#trace 10.0.10.3
> Type escape sequence to abort.
> Tracing the route to 10.0.10.3
>
> 1 10.1.2.1 0 msec 0 msec 4 msec
> 2 10.0.10.3 4 msec 0 msec *
>
>
> Now I add a VL between BOTTOM and R5(which has the s0/0 connection to
> BOTTOM)
>
> R5#
> BOTTOM#
> 00:08:04: %OSPF-4-ERRRCV: Received invalid packet: mismatch area ID, from
> backbo
> ne area must be virtual-link but not found from 10.1.1.1, Serial0/0
>
> BOTTOM(config)#router os 10
> BOTTOM(config-router)#area 1 vir 200.200.200.200
> BOTTOM(config-router)#^Z
> BOTTOM#
> BOTTOM#sh ip ro
> Codes: C - connected, S - static, I - IGRP, 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, 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 not set
>
> 192.192.192.0/32 is subnetted, 1 subnets
> O 192.192.192.192 [110/1573] via 10.1.1.1, 00:00:02, Serial0/0
> 10.0.0.0/8 is variably subnetted, 6 subnets, 2 masks
> O 10.0.10.0/24 [110/1572] via 10.1.1.1, 00:00:02, Serial0/0 <<<Now
> via the serial!!!!
> O 10.2.10.10/32 [110/65] via 10.2.0.2, 00:00:02, Serial0/1
> C 10.2.0.0/24 is directly connected, Serial0/1
> O IA 10.3.0.0/24 [110/1620] via 10.1.1.1, 00:00:02, Serial0/0
> C 10.1.2.0/24 is directly connected, Ethernet0/0
> C 10.1.1.0/24 is directly connected, Serial0/0
> BOTTOM#
>
>
>
>
>
>
This archive was generated by hypermail 2.1.4 : Thu Jun 13 2002 - 08:25:58 GMT-3