[c-nsp] IOS XR / advertise best-external

[Dan Peachey]

On 17 May 2015 9:48 pm, "Gert Doering" <gert at greenie.muc.de> wrote:
>
> Hi,
>
> On Sun, May 17, 2015 at 08:40:08PM +0100, Dan Peachey wrote:
> > > IOS XR 4.3.4SP6 on ASR9001.
> [..]
> >
> > I have used this in the past on ASR9001 which was running 4.3.4 SP1
IIRC.
> > Unfortunately I don't have access to this network anymore to double
check
> > but I'm pretty certain this is not the behaviour I observed. The
> > best-external path should be seen as an additional path in the BGP table
> > but not be installed in the RIB/FIB as far as I understand.
>
> Glad you say that :-) - so this might turn out to be a bug, or some
> combination of "things", and not intended behaviour...
>
> > I assume there is nothing else in your BGP config which might be causing
> > this? No 'additional-paths' or 'maximum-paths' commands for example?
>
> Unless it's on-by-default, no.  "show run formal | inc path" only
> has route-map / as-path stuff, nothing regarding add-path etc. (which
> my other routers don't support, so I'm not yet going there).

I find the behaviour strange then and not what I've seen before. My setup
was slightly different in that I was also using 'additional-paths' with a
policy to selectively install PIC edge backup routes for prefixes marked
with certain communities, but those that were not caught by this policy had
single routes installed in RIB/FIB.

I'll be interested to see if you manage to find a resolution.

Regards,

Dan