From: TK-Network Çözümleri (umit.askan@xxxxxxxxxxxxx)
Date: Tue Aug 13 2002 - 09:45:35 GMT-3
Hi,
This is the OSPF normal behaviour. Virtual links are the part of Area 0.
So R3 is connected to area 0 directly.
R3 sees R1's loopback addr O because it has an int at area 0 ( virt link
).
R1 sees R3's loopback O IA because it is on area 2 ( so at different
area )
Put another loopback on R3. Put it on area 0.
at the situation you will see that net O at R1.
Hope this helps
umit
-----Original Message-----
From: Hunt Lee [mailto:ciscoforme3@yahoo.com.au]
Sent: Tuesday, August 13, 2002 14:19
To: ccielab@groupstudy.com
Subject: OSPF virtual link
This is the network:
RTA ----- RTB ----- RTC
RTA's interface to RTB:- 10.1.1.1
RTB's interface back to RTA:- 10.1.1.2
RTB's interface to RTC:- 10.1.1.5
RTC's interface back to RTB:- 10.1.1.6
Each router also it's own Loopback interface, where RTA has
1.1.1.1/32, RTB has 2.2.2.2/32 & RTC has 3.3.3.3/32
All 3 routers are running OSPF, please see configs as below:-
At RTA:-
router ospf 1
log-adjacency-changes
network 1.1.1.1 0.0.0.0 area 0
network 10.1.1.0 0.0.0.3 area 0
At RTB:-
router ospf 2
log-adjacency-changes
area 1 virtual-link 3.3.3.3
network 2.2.2.2 0.0.0.0 area 0
network 10.1.1.0 0.0.0.3 area 0
network 10.1.1.4 0.0.0.3 area 1
At RTC:-
router ospf 3
log-adjacency-changes
area 1 virtual-link 2.2.2.2
network 3.3.3.3 0.0.0.0 area 2
network 10.1.1.4 0.0.0.3 area 1
Since Area 2 on RTC does not have a direct connection to Area 0, I
have configured a Virtual Link for this (the transit area is Area 1).
What I don't understand is that from RTA, it sees RTC's Loopback
address via Inter-Area route (O IA), but at RTC, RTC sees RTA's
Loopback address via Intra-Area route (O). Shouldn't they be both
OIA or O routes?? Why would they be different?
RouterA#sh ip route
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
1.0.0.0/32 is subnetted, 1 subnets
C 1.1.1.1 is directly connected, Loopback0
2.0.0.0/32 is subnetted, 1 subnets
O 2.2.2.2 [110/65] via 10.1.1.2, 00:40:52, Serial0
3.0.0.0/32 is subnetted, 1 subnets
O IA 3.3.3.3 [110/129] via 10.1.1.2, 00:40:52, Serial0
10.0.0.0/30 is subnetted, 2 subnets
C 10.1.1.0 is directly connected, Serial0
O IA 10.1.1.4 [110/128] via 10.1.1.2, 00:40:52, Serial0
RouterA#
RouterC#sh ip route
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
1.0.0.0/32 is subnetted, 1 subnets
O 1.1.1.1 [110/129] via 10.1.1.5, 00:41:04, Serial0
2.0.0.0/32 is subnetted, 1 subnets
O 2.2.2.2 [110/65] via 10.1.1.5, 00:41:04, Serial0
3.0.0.0/32 is subnetted, 1 subnets
C 3.3.3.3 is directly connected, Loopback0
10.0.0.0/30 is subnetted, 2 subnets
O 10.1.1.0 [110/128] via 10.1.1.5, 00:41:04, Serial0
C 10.1.1.4 is directly connected, Serial0
RouterC#
RouterB#sh ip route
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
1.0.0.0/32 is subnetted, 1 subnets
O 1.1.1.1 [110/65] via 10.1.1.1, 00:41:42, Serial1
2.0.0.0/32 is subnetted, 1 subnets
C 2.2.2.2 is directly connected, Loopback0
3.0.0.0/32 is subnetted, 1 subnets
O IA 3.3.3.3 [110/65] via 10.1.1.6, 00:41:42, Serial0
10.0.0.0/30 is subnetted, 2 subnets
C 10.1.1.0 is directly connected, Serial1
C 10.1.1.4 is directly connected, Serial0
RouterB#
Thanks
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