PT: OSPFv3 ABR does not always distribute default route to totally stubby areas

[bilowik]

Hi,

I've recently made myself familiar with OSPF, and have had success with other multi-area configurations, however with this one in particular I made use of totally stubby areas, and it seems like it's a coinflip whether or not the ABR will distribute a default route. If I power cycle all the routers or re-open the packet tracer file, sometimes they receive a default route, and sometimes they don't. When the default route is distributed, communication flows as normal, when it's not, communication does not. Here's a short checklist of potential issues I've covered already:

 - All routers in totallly stubby areas are configured with "ospf 1 area M stub no-summary"

 - The ABR is also configured with "ospf 1 area M stub no-summary" for both totally stubby areas

 - WAN links are all properly configured to be within the same networks

The packet trace file is attached. I'm running version 7.2.2, haven't been able to update yet due to the newest version being packaged as a .deb file, which cannot be used for installation on my system. 
Also apologies for the lack of labeling and naming of the routers, this was meant to be a quick practice example for myself. 

Edit: I'd also like to note that all routes inside the local areas are properly distributed and communication within each area works as intended.

Edit 2: 

ipv6 cef did not seem to make a difference in either totally stubby area after being applied to each router, copy run start, then power cycling. Reopening the file also seemed to still produce the issue. 

I did find out that I can guarantee the default route distribution in both areas, if the area 2 router that's directly connected to the ABR is down when the ABR comes back up. Maybe this is helpful to finding the root cause? 
 - Power off ABR

 - Power off Area 2 router directly connected to the ABR

 - Power on ABR and wait for it to distribute default route to Area 1

 - Power on Area 2 router directly connected to the ABR

 - ABR distributes default route to Area 1

Edit 3: i've attached a crude diagram of the setup that has labels that match the names given in the attached configs.txt so the whole pt does not have to be launched to get a grasp of the setup. 

[ashok_boin]

I think the default route is getting injected from ABR when you power this before other routers in Totally stubby areas.

During non-injection, have you seen LSDB whether ABR is self-genearting the default route? When you don't see it, can you try with removing "area x stub no-summary" and re-adding?

Pls check the following link as well.

https://community.cisco.com/t5/routing/regarding-ospf-stub-area-default-route/td-p/2919396

[Georg Pauwen]

Hello,

looking at your design, I think the problem is that you have the ABR and the three area 1 routers connected to a switch. When I open the file, the DR is Router 0 (ID 3.0.0.1). Try and redesign you network so that only one router is connected to the ABR, and check if the problem persists...

[bilowik]

---

@Georg Pauwen wrote:

Hello,

looking at your design, I think the problem is that you have the ABR and the three area 1 routers connected to a switch. When I open the file, the DR is Router 0 (ID 3.0.0.1). Try and redesign you network so that only one router is connected to the ABR, and check if the problem persists...

---

Sorry I should've specified that the ABR doesn't distribute a default route to either areas, including the one that is connected via just a single router. But I will try and swap out the switch for a router and rework the addresses and see if anything changes.

As for the ipv6 cef configuration command, it did not seem to make a difference in either totally stubby area. 

However I did find out that I can guarantee the default route distribution in both areas, if the area 2 router that's directly connected to the ABR is down when the ABR comes back up. Maybe this is helpful to finding the root cause? 
 - Power off ABR

 - Power off Area 2 router directly connected to the ABR

 - Power on ABR and wait for it to distribute default route to Area 1

 - Power on Area 2 router directly connected to the ABR

 - ABR distributes default route to Area 1

Thanks for the assistance so far I appreciate it!

[Giuseppe Larosa]

Hello @bilowik ,

on all routers

conf t

ipv6 cef

a common link in each area must connect the ABR (0,1,2) with routers in area  0,1,2 if you are using an emulated switch it is like an HUB and does not create three different Vlans connect the routers to the ABR using p2p links instead of going through an emulated switch as recommeded by @Paul Driver

Hope to help

Giuseppe