Hi Balaji,
Router A--------Router B---------Router C
Lets say Router B and C have an RIP session and Router A and B have OSPF
session. Router B's RIP is redistributing OSPF.
Router B learns 50.1.1.0/24 route from Router A through OSPF and
redistributes that route to Router C.
Now On Router B, user configures a static route with same prefix (
50.1.1.0/24). This static route on router B will be chosen as best
route because
of lesser administrative distance.
Now question is Doesn't Router B withdraw its earlier distributed OSPF
route (50.1.1.0/24) from Router C ?
Rgds
Atul
On Fri, May 12, 2017 at 10:54 AM, Balaji Gurudoss <balaji...@gmail.com>
wrote:
> Hi Atul
>
> My example also is about configuring static route on the same box where
> the route is learned as an OSPF route.
>
> Can you let me know if my understanding below is right
>
> Router A--------Router B
>
> 1.Router B has a static route configured (eg: 50.1.1.0/24 10.1.1.50)
> 2. Router B has redistribute static configured
> 3. There is OSPF/BGP session configured between Router A and Router B
> 4. On Router A the prefix 50.1.1.0/24 would be shown as an OSPF/BGP
> learned route
> 5. On Router A a static route pointing to 50.1.1.0/24 is now configured
> with a different next-hop.
> 6. On Router A, the static route is displayed as the best route instead of
> the OSPF route because of lesser administrative distance for static route.
>
> Now in the above mentioned scenario, what is your expectation and whats
> your question
>
> Thanks,
> - Balaji
>
>
>
> On Fri, May 12, 2017 at 11:11 PM, Atul Chowdhry <atu...@gmail.com> wrote:
>
>> Hi Balaji,
>> May be I am missing something but I am talking about both static and OSPF
>> route on same router. In ur example, Its assuming that static route is
>> added on Router B rather than A.
>> Any other quagga Guru, who can pls clarify my query here ?
>>
>> Rgds
>> Atul
>>
>> On Wed, May 10, 2017 at 7:56 PM, Balaji Gurudoss <balaji...@gmail.com>
>> wrote:
>>
>>> Hi Atul
>>>
>>> This would happen with any protocol and not with ospf because this is an
>>> expected behaviour. I believe the following is what you are looking at
>>>
>>> Router A-----Router B
>>>
>>> You have configured a static route in Router B and are doing a
>>> redistribute static into OSPF/BGP in Router B. The show ip route on Router
>>> B would show the route as a BGP/OSPF learned route. Now on router B you
>>> configure a static route with the same prefix pointing to a next-hop and in
>>> RTM the newly created static route would be marked as the Best route
>>> instead of BGP as the static route has more preference.
>>>
>>> Now as per BGP/OSPF is concerned, 50.1.1.0/24 is still the best route
>>> on the router where the route was originated i.e Router B. On router A it
>>> isn't the best route because a static route for the same prefix has been
>>> created. In this scenario why should Router B withdraw the route ? How
>>> would router B know that there is a static route existing in Router A for
>>> the same destination ?
>>>
>>> Hope you get my point.
>>>
>>> Thanks,
>>> - Balaji
>>>
>>>
>>> On Thu, May 11, 2017 at 12:07 AM, Atul Chowdhry <atu...@gmail.com>
>>> wrote:
>>>
>>>> Hi Balaji,
>>>> What do you mean when you say implicit withdraw ? I am seeing this in
>>>> very simple topology of two routers running ospf and connected back to
>>>> back.
>>>>
>>>> Rgds
>>>> Atul
>>>>
>>>> On Wed, May 10, 2017 at 11:03 AM, Balaji Gurudoss <balaji...@gmail.com>
>>>> wrote:
>>>>
>>>>> Ideally speaking the implicit withdraw would happen when the new one
>>>>> gets selected and old one gets validated. Are you seeing this issue with a
>>>>> very simple topology with two routers connected back to back running OSPF
>>>>> or do you see it in a specific topology ?
>>>>>
>>>>> Thanks,
>>>>> - Balaji
>>>>>
>>>>> On Wed, May 10, 2017 at 10:27 PM, Atul Chowdhry <atu...@gmail.com>
>>>>> wrote:
>>>>>
>>>>>> Hi Guys,
>>>>>> I am using quagga release 1.2.1. I see one potential problem in
>>>>>> rib_process function related to withdrawal of redistributed route from
>>>>>> zebra.
>>>>>> Problematic line is marked in bold letters.
>>>>>> Suppose a prefix was already learned via OSPF. Now if I try to add a
>>>>>> static route for same prefix, I hit this code.
>>>>>> In this case. old_selected will point to OSPF and new_selected will
>>>>>> point to Static. Now since ospf route is not the selected one, don;t we
>>>>>> always have to withdraw this ospf route from clients redistributing
>>>>>> OSPF. Why there is extra check there ?
>>>>>> I also tested this locally. If I comment this if statement then I see
>>>>>> zebra sending delete for OSPF route else not.
>>>>>>
>>>>>> Pls give advice.
>>>>>>
>>>>>> Rgds
>>>>>> Atul
>>>>>>
>>>>>>
>>>>>> /* Redistribute SELECTED entry */
>>>>>> 1308 if (old_selected != new_selected
>>>>>> 1309 || (new_selected && CHECK_FLAG (new_selected->status,
>>>>>> RIB_ENTRY_CHANGED)))
>>>>>> 1310 {
>>>>>> 1311 if (old_selected)
>>>>>> 1312 {
>>>>>> 1313 * if (! new_selected) >>>> Why this if statement
>>>>>> is there ?? I fell this shouldn't be there.*
>>>>>> 1314 redistribute_delete (&rn->p, old_selected);
>>>>>> 1315 if (old_selected != new_selected)
>>>>>> 1316 UNSET_FLAG (old_selected->flags,
>>>>>> ZEBRA_FLAG_SELECTED);
>>>>>> 1317 }
>>>>>> 1318
>>>>>> 1319 if (new_selected)
>>>>>> 1320 {
>>>>>> 1321 /* Install new or replace existing redistributed entry
>>>>>> */
>>>>>> 1322 SET_FLAG (new_selected->flags, ZEBRA_FLAG_SELECTED);
>>>>>> 1323 redistribute_add (&rn->p, new_selected);
>>>>>> 1324 }
>>>>>> 1325 }
>>>>>>
>>>>>>
>>>>>> _______________________________________________
>>>>>> Quagga-users mailing list
>>>>>> Quagga-users@lists.quagga.net
>>>>>> https://lists.quagga.net/mailman/listinfo/quagga-users
>>>>>>
>>>>>>
>>>>>
>>>>
>>>
>>
>
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