From: Jonathan Hays (jhays@xxxxxxxx)
Date: Wed May 15 2002 - 15:04:09 GMT-3
I am puzzled why Router A loopback 0 (10.1.1.1/24) and Router B loopback
0 (152.1.1.1/24) do not appear in the link state database below. These
routes do not appear despite the fact the lo0 interfaces are configured
for OSPF in each router and despite the fact that each router's routing
table shows an OSPF route for the other router's loopback 0.
I am not new to OSPF but I am looking at every little detail in
preparation for the CCIE lab. Maybe I need to do some more reading?
Any help would be appreciated.
Jonathan
= = = = =
DETAILS:
This scenario is from Lab #33 of "Cisco CCIE LAB Study Guide, Second
Edition" by Hutnik and Satterlee.
In brief, two routers are running OSPF over a directly connected serial
link. I have given relevant configuration for each router at the bottom
of my post.
Here is the link state database (same on both routers, of course):
RouterA#sh ip ospf database.
OSPF Router with ID (11.1.1.1) (Process ID 64)
Router Link States (Area 0)
Link ID ADV Router Age Seq# Checksum Link
count
11.1.1.1 11.1.1.1 599 0x80000006 0xA0A1 3
153.1.1.1 153.1.1.1 597 0x80000009 0xFB77 4
RouterA#
And here is proof that OSPF is running on those loopback 0 interfaces:
- - - - -
RouterA#show ip ospf interface
Loopback0 is up, line protocol is up
Internet Address 10.1.1.1/24, Area 0
Process ID 64, Router ID 11.1.1.1, Network Type LOOPBACK, Cost: 1
Loopback interface is treated as a stub Host
Serial0 is up, line protocol is up
Internet Address 192.1.1.1/24, Area 0
Process ID 64, Router ID 11.1.1.1, Network Type POINT_TO_POINT, Cost:
64
Transmit Delay is 1 sec, State POINT_TO_POINT,
Timer intervals configured, Hello 10, Dead 40, Wait 40, Retransmit 5
Hello due in 00:00:09
Neighbor Count is 1, Adjacent neighbor count is 1
Adjacent with neighbor 153.1.1.1
Suppress hello for 0 neighbor(s)
RouterA#
- - - - -
RouterB#sh ip ospf interface
Loopback0 is up, line protocol is up
Internet Address 152.1.1.1/24, Area 0
Process ID 64, Router ID 153.1.1.1, Network Type LOOPBACK, Cost: 1
Loopback interface is treated as a stub Host
Loopback1 is up, line protocol is up
Internet Address 153.1.1.1/24, Area 0
Process ID 64, Router ID 153.1.1.1, Network Type LOOPBACK, Cost: 1
Loopback interface is treated as a stub Host
Serial0 is up, line protocol is up
Internet Address 192.1.1.2/24, Area 0
Process ID 64, Router ID 153.1.1.1, Network Type POINT_TO_POINT, Cost:
64
Transmit Delay is 1 sec, State POINT_TO_POINT,
Timer intervals configured, Hello 10, Dead 40, Wait 40, Retransmit 5
Hello due in 00:00:07
Neighbor Count is 1, Adjacent neighbor count is 1
Adjacent with neighbor 11.1.1.1
Suppress hello for 0 neighbor(s)
RouterB#
- - - - -
And both routers see each other's loopback 0 via OSPF in their routing
tables.
RouterA sees 152.1.1.1 which is the loopback 0 on Router B.
- - - - -
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, * - candidate
default
U - per-user static route, o - ODR
Gateway of last resort is not set
153.1.0.0/32 is subnetted, 1 subnets
O 153.1.1.1 [110/65] via 192.1.1.2, 00:17:38, Serial0
152.1.0.0/32 is subnetted, 1 subnets
O 152.1.1.1 [110/65] via 192.1.1.2, 00:17:38, Serial0
10.0.0.0/24 is subnetted, 1 subnets
C 10.1.1.0 is directly connected, Loopback0
11.0.0.0/24 is subnetted, 1 subnets
C 11.1.1.0 is directly connected, Loopback1
C 192.1.1.0/24 is directly connected, Serial0
RouterA#
- - - - -
And RouterB sees 10.1.1.1 which is the loopback 0 on Router A.
- - - - -
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, * - candidate
default
U - per-user static route, o - ODR
Gateway of last resort is not set
153.1.0.0/24 is subnetted, 1 subnets
C 153.1.1.0 is directly connected, Loopback1
152.1.0.0/24 is subnetted, 1 subnets
C 152.1.1.0 is directly connected, Loopback0
10.0.0.0/32 is subnetted, 1 subnets
O 10.1.1.1 [110/65] via 192.1.1.1, 00:16:50, Serial0
C 192.1.1.0/24 is directly connected, Serial0
RouterB#
= = = = =
CONFIGURATIONS
hostname RouterA
!
interface Loopback0
ip address 10.1.1.1 255.255.255.0
!
interface Loopback1
ip address 11.1.1.1 255.255.255.0
!
interface Serial0
ip address 192.1.1.1 255.255.255.0
!
router ospf 64
network 10.1.1.1 0.0.0.0 area 0
network 192.1.1.1 0.0.0.0 area 0
= = = = =
hostname RouterB
!
interface Loopback0
ip address 152.1.1.1 255.255.255.0
!
interface Loopback1
ip address 153.1.1.1 255.255.255.0
!
interface Serial0
ip address 192.1.1.2 255.255.255.0
clockrate 500000
!
router ospf 64
network 0.0.0.0 255.255.255.255 area 0
!
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