[OSPF] Fw: Tye - 5 and Type -3 LSA issues

[Jennifer Christy <[e-mail]>]

Hi ,

We are using zebra-0.93b in all the routers , installed it in three linux boxes.

As per the topology ( PPT attached ) , we have three routers A , B , C in our setup.
Steps to reproduce the issue :
1. Router A is sending a Type 5 LSA route 172.25.25.0/24 ( External Route ) via 11.11.11.11 to Router C.
2. Router B is sending a Type 3 LSA route 172.25.25.0/24 via 12.12.12.12 to Router C.

Let me explain the issue.

Case 1 :

1. Enable OSPF in Router C on interface ( 12.12.12.10 ) 
2. Then Type - 3 LSA Route 172.25.25.0/24 via 12.12.12.12 from Router B will be added to Router C.
3. Now Router C will have the route 172.25.25.0/24 via 12.12.12.12. ( Added by Type -3 LSA )
4. Enable OSPF in Router C opn interface ( 11.11.11.10 )
5. Then Type - 5 LSA Route 172.25.25.0/24 from Router A is not added to Router C , because while comparing the Type - 5 and Type - 3 , its adding the best route as Type - 3 Route.
6. So the Router will have the Type - 3 route in routing table

Case 2 : 

1. Enable OSPF in Router C on interface ( 11.11.11.10 ).
2. Then Type - 5 LSA Route 172.25.25.0/24 via 11.11.11.11 from Router A will be added to Router C.
3. Now Router C will have the route 172.25.25.0/24 via 11.11.11.11 ( Added by Type -5 LSA )
4. Enable OSPF in Router C on interface ( 12.12.12.10 ) 
5. Now Type - 3 ( 172.25.25.0/24 via 12.12.12.12 ) is the best route when compared to Type -5 route 
( 172.25.25.0/24 via 11.11.11.11 ) , so zebra is sending a message to delete the Type -5 route.
6. And its sending a message to add the Type -3 route.So Type - 3 route is added into the Router C.
7. Here the issue starts , again zebra is sending a message to delete the existing the Type - 3 route from the Router C.
8. So the Type - 3 route is deleted from the routing table , now there is no routes for 172.25.25.0/24 in the routing table.

This is the real issue , not happening when u enable type -3 first.

We dont know this is an usual behaviour or its really an issue
Please let us know the this is an already existing issue or if any patch is there for this issue that would be fine.

We want to know the root cause analysis of this issue .
Its a long mail but hope you understand it.
Please reply as soon as possible.

Note :
The issue is reproducible in latest version also ( zebra-0.95a ) 
If you need any help in reproducing / understanding the issue , please let us know.

Thanks in Advance ,
Jenny


      

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