[j-nsp] Aggregate and directly connected routes (route preference)

[Gary Tate]

If you use the 'from protocol aggregate' as your match condition and 
you use advertise inactive you will only advertise the aggregates and 
not the interface routes.

If you use a route filter as the match with advertise inactive then the 
interface route will be advertised as the preferred route and then if 
it should go down the aggregate will take its place.

Your choice.  In your case it sounds like the first choice suites your 
needs best.

Gary

On Jan 26, 2004, at 6:30 PM, Robin Balen wrote:

>
>
>> -----Original Message-----
>> From: Gary Tate [mailto:gtate at juniper.net]
>> Sent: 27 January 2004 02:18
>
> Gary,
>
>> You could advertise the aggregate if you really want to by using
>> advertise-inactive option on the bgp group or neighbor that you wish
>> the aggregate to be advertised on.  This is needed because as
>> you have mentioned the aggregate will always be inactive in this
>> configuration.
>
> This sounds good for this specific scenario, as I would like the 
> routes to
> be announced independently to the status of the physical interfaces. 
> This is
> why I was going to use the aggregate method, even though I'm not 
> actually
> aggregating anything.
>
>> However, if the interfaces which have the actual routes go down the
>> route will still be advertised and you will sink traffic to
>> your router before it is dropped.
>
> That makes sense - thanks!
>
> The advertise-inactive option will choose the "best" route, even if it 
> is
> not active. This sounds like what I need. However, would the aggregate
> routes be considered the "best" route, or would the interface routes 
> take
> priority again? I guess it doesn't actually matter because if the 
> interface
> routes are withdrawn due to the interface going down, then the 
> aggregate
> routes would step up and be announced instead.
>
> If that's not going to work, just using the interface routes will do 
> the job
> just fine.
>
> Thanks for providing a sounding board!
>
> Robin Balen
>
>
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