Re: OSPF default route multiple processes

Thanks, Jose...

On Fri, Jul 26, 2013 at 9:10 PM, Jose Zamora <joszompr_at_gmail.com> wrote:

> In this case both OSPF process are treated as different routing protocol
> instances so the router is going to compare de AD of both to select the
> best route, in case of a tie like in this escenario its going to select the
> one learned first.
>
> Because of this it could work like you expect for a while but a
> convergence on the network could change the behavior.
>
> You could change the AD of one of the process to force it to use the
> default you want
>
> Regards
>
> Jose
>
>
> On Fri, Jul 26, 2013 at 11:24 AM, Kristian Francisco <
> kristian.j.f_at_gmail.com> wrote:
>
>> Hey Marc, I would like to take a stab at your questions, but will let some
>> of the CCIEs with more experience confirm. I would expect the following to
>> take place:
>>
>> Although there are two ospf processes running, there's only one routing
>> table. I would not expect ospf to treat its rules on route selection
>> differently. (this is an assumption). For true segmentation, consider
>> vrfs.
>>
>> As you mentioned, the type-1 LSA to be preferred over a type-2 LSA. Once
>> you make the default routes both of the same type, the following selection
>> criteria will apply:
>>
>> - If type-2 metric is the same, prefer route with better internal cost.
>> - Directly from RFC: In any case, among the remaining routing table
>>
>> entries, select the routing table entry with the least cost; when
>> there are
>> multiple least cost routing table entries the entry whose associated
>> area
>> has the largest OSPF Area ID (when considered as an unsigned 32-bit
>> integer) is chosen.
>>
>> Best Regards,
>>
>> Kristian J. Francisco
>>
>>
>> On Fri, Jul 26, 2013 at 10:20 AM, Marc La Porte <marc.a.laporte_at_gmail.com
>> >wrote:
>>
>> > Rati,
>> >
>> > How does it choose between the two processes though?
>> >
>> > Cheers,
>> > Marc
>> >
>> > On Fri, Jul 26, 2013 at 7:12 PM, Rati Berikaant Jokhadze
>> > <iinfo83_at_gmail.com>wrote:
>> >
>> > >
>> > > On 07/26/2013 08:50 PM, Marc La Porte wrote:
>> > >
>> > >> 1. What is the order of operation within OSPF to select default
>> routes
>> > >> from
>> > >> different processes?
>> > >>
>> > >> 2. How do I ensure the border router ALWAYS takes the default route
>> from
>> > >> Area 51 (although it has multiple default routes from Area 0 in it's
>> > >> database)? Since OSPF metric-type 1 has preference over metric-type
>> 2,
>> > do
>> > >> I
>> > >> change the metric-type in Area 51 to type 2 and ensure it's always
>> lower
>> > >> than from Area 0?
>> > >>
>> > > 1. First recieved route within process
>> > >
>> > > 2. I dont think so , that you can do this , someone will answer
>> > exactly...
>> >
>> >
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>
>
> --
> Atentamente Jose Zamora Prado
> Telefono 8252885

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Received on Fri Jul 26 2013 - 23:26:29 ART