3

OSPF Topology

Problem Description

I am having an issue with LSA Type 3's, on R7 in the topology i have 4 loopback addresses

Loopback1 is up, line protocol is up
Internet address is 192.168.100.1/28
Loopback2 is up, line protocol is up
Internet address is 192.168.100.17/28
Loopback3 is up, line protocol is up
Internet address is 192.168.100.33/28
Loopback4 is up, line protocol is up
Internet address is 192.168.100.49/29

I change the OSPF network type on all these links to : Network Type POINT_TO_POINT

On R7 under : router ospf 123, i have 

network 192.168.100.0 0.0.0.255 area 44

on r6 i have the command 

area 44 range 192.168.100.0 255.255.255.0

R6's routing table

R6#show ip route | i 168.100

   192.168.100.0/24 is variably subnetted, 5 subnets, 2 masks
   O       192.168.100.0/28 [110/11] via 192.168.1.129, 00:00:02, FastEthernet0/1
   O       192.168.100.0/24 is a summary, 00:00:02, Null0
   O       192.168.100.16/28 
   O       192.168.100.32/28 
   O       192.168.100.48/28

As expected, i can see my summary with Null0 and the subordinate routes - all ok here.

but here is R5

   R5#show ip route | i 168.100
 192.168.100.0/24 is variably subnetted, 5 subnets, 2 masks
   O IA    192.168.100.0/28 [110/21] via 192.168.1.2, 00:01:50, FastEthernet0/1
   O IA    192.168.100.0/24 [110/21] via 192.168.1.2, 00:02:36, FastEthernet0/1
   O IA    192.168.100.16/28 [110/21] via 192.168.1.2, 00:01:40, FastEthernet0/1
   O IA    192.168.100.32/28 [110/21] via 192.168.1.2, 00:01:30, FastEthernet0/1
   O IA    192.168.100.48/28 [110/21] via 192.168.1.2, 00:01:20, FastEthernet0/1

This is not meant to happen, i am only meant to see 

   O IA    192.168.100.0/24 [110/21] via 192.168.1.2, 00:02:36, FastEthernet0/1

its the same all the way along to r1

R1#show ip route | i 168.100 
     192.168.100.0/24 is variably subnetted, 5 subnets, 2 masks
O IA    192.168.100.0/28 [110/61] via 10.1.1.2, 00:03:04, FastEthernet0/0
O IA    192.168.100.0/24 [110/61] via 10.1.1.2, 00:03:50, FastEthernet0/0
O IA    192.168.100.16/28 [110/61] via 10.1.1.2, 00:02:54, FastEthernet0/0
O IA    192.168.100.32/28 [110/61] via 10.1.1.2, 00:02:44, FastEthernet0/0
O IA    192.168.100.48/28 [110/61] via 10.1.1.2, 00:02:34, FastEthernet0/0

The reason area 0 is where it is, i was practicing virtual links

if you can shed any light on why the subordinate rotes are being advertised i would be very grateful

Andy

Improve this question
1
  • Did any answer help you? if so, you should accept the answer so that the question doesn't keep popping up forever, looking for an answer. Alternatively, you could provide and accept your own answer.
    – Ron Maupin ♦
    Commented Aug 9, 2017 at 2:06

1 Answer 1

Reset to default
2

Your topology violates OSPF rules. All your areas must be adjacent to area 0. Area 44 and 50 are not adjacent to area 0.

Improve this answer
4
  • I agree its poor design and should only be used as a last resort. However it is possible to have areas that are not adjacent to area 0 with the use of virtual links. However I will try and recreate the lab with better/proper network design.
    – psniffer
    Commented Aug 23, 2014 at 11:49
  • I would argue that virtual links makes them adjacent. But in any case, that wasn't part of the design you presented.
    – Ron Trunk
    Commented Aug 23, 2014 at 20:38
  • Firstly thanks for taking the time to answer, I appreciate it. I managed to get it working, I did very briefly mention the virtual links at the end of the original problem. The problem turned out to be a miss configuration of the virtual links. Thanks again.
    – psniffer
    Commented Aug 23, 2014 at 20:43
  • Ah yes, I see that now. I saw the topology diagram and jumped to conclusions. Sorry for not reading more carefully. Glad you got it working.
    – Ron Trunk
    Commented Aug 24, 2014 at 0:18

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.