Dual OSPF Issue

From: Varghese Thomas (vnthomas2@hotmail.com)
Date: Tue Dec 02 2003 - 12:58:17 GMT-3

Hello,

Need help on a dual OSPF issue.

Setup is as follows:

BB1 - 192.168.1.0/24 R1 - 10.2.2.0/24 R2 - 172.16.1.0/24 BB2

Requirement:

1. R1 & R2 should only pass default-route learned from BB1 & BB2 respectively
2. If BB1 stops sending default-route, R1 should have default-route from BB2
via R2; vice vesa.
3. When all are working, both BB1 is sending external default-route, type 1.

BB1 & R1 is running OS process 64, R1 & R2 is running OSPF process 1; R2 & BB2
is ruuning OSPF process 64.

R1's Config:

router ospf 1
 log-adjacency-changes
 network 10.2.2.0 0.0.0.255 area 0
 default-information originate
!
router ospf 64
 log-adjacency-changes
 network 192.168.1.0 0.0.0.255 area 0

R2's config:
router ospf 1
 log-adjacency-changes
 network 10.2.2.0 0.0.0.255 area 0
 default-information originate
!
router ospf 64
 log-adjacency-changes
 network 172.16.1.0 0.0.0.255 area 0

R1's RT

R1#sip | in 0.0.0.0
Gateway of last resort is 10.2.2.2 to network 0.0.0.0
    10.0.0.0/24 is subnetted, 1 subnets
O*E1 0.0.0.0/0 [110/11] via 192.168.1.2, 00:00:12, FastEthernet0/1

R2's RT:

R2#sh ip route | in 0.0.0.0
Gateway of last resort is 172.16.1.2 to network 0.0.0.0
     10.0.0.0/24 is subnetted, 1 subnets
O*E1 0.0.0.0/0 [110/11] via 172.16.1.2, 00:10:49, FastEthernet0/0

However, if I bring down, r1-bb1 link or r2-bb2 link, and brings back, things
are different.

R1' RT:

Gateway of last resort is 10.2.2.2 to network 0.0.0.0
     10.0.0.0/24 is subnetted, 2 subnets
O*E2 0.0.0.0/0 [110/1] via 10.2.2.2, 00:00:26, FastEthernet0/0

R1 prefers E2 route than a E1 route:

If I make route-metric type to E1, it still prefers higher metric route:

R1#sip | in 0.0.0.0

Gateway of last resort is 10.2.2.2 to network 0.0.0.0
     10.0.0.0/24 is subnetted, 2 subnets
O*E1 0.0.0.0/0 [110/20001] via 10.2.2.2, 00:14:54, FastEthernet0/0

R1' OSPF DB:

R1#sh ip os da ex 0.0.0.0

            OSPF Router with ID (192.168.1.1) (Process ID 64)

                Type-5 AS External Link States

  LS age: 2703
  Options: (No TOS-capability, DC)
  LS Type: AS External Link
  Link State ID: 0.0.0.0 (External Network Number )
  Advertising Router: 12.12.12.51
  LS Seq Number: 80000002
  Checksum: 0x6179
  Length: 36
  Network Mask: /0
        Metric Type: 1 (Comparable directly to link state metric)
        TOS: 0
        Metric: 1
        Forward Address: 0.0.0.0
        External Route Tag: 1

  Routing Bit Set on this LSA
  LS age: 1216
  Options: (No TOS-capability, DC)
  LS Type: AS External Link
  Link State ID: 0.0.0.0 (External Network Number )
  Advertising Router: 192.168.1.2
  LS Seq Number: 80000001
  Checksum: 0x982E
  Length: 36
  Network Mask: /0
        Metric Type: 1 (Comparable directly to link state metric)
        TOS: 0
        Metric: 1
        Forward Address: 0.0.0.0
        External Route Tag: 1

            OSPF Router with ID (10.1.1.1) (Process ID 1)

                Type-5 AS External Link States

  Routing Bit Set on this LSA
  LS age: 978
  Options: (No TOS-capability, DC)
  LS Type: AS External Link
  Link State ID: 0.0.0.0 (External Network Number )
  Advertising Router: 172.16.1.1
  LS Seq Number: 80000001
  Checksum: 0x185C
  Length: 36
  Network Mask: /0
        Metric Type: 1 (Comparable directly to link state metric)
        TOS: 0
        Metric: 1
        Forward Address: 0.0.0.0
        External Route Tag: 1

Thanks in advance.

Tx n RD

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