default route via OSPF depending on the ISP

[Gruber Gerold]

Am 08.12.2015 um 11:37 schrieb Raphael Mazelier:
> 
> 
> Le 08/12/15 10:56, Ondrej Zajicek a écrit :
>> On Mon, Dec 07, 2015 at 12:07:59PM +0000, Rohrmann Sascha wrote:
>>
>> I would not stup the whole routing process, i would just shut down static
>> protocol (XXX instead of name in the example) used to originate the
>> default route.
>>
> 
> Why not just changing the metric of the route ?
Raphael,

could you explain this idea a little for me?

we have a router, eBGP connected to an upstream provider, iBGP connected
to its neighbour, which has the other upstream connection.
Both of them get a whole bunch of routes.
But to the internal network they shall only propagate a default route,
if *any* upstream is reachable.

So besides checking the functionality of BGP to the neighbour or just
the IP connectivity it could also be a test which checks if there are
more then say 100 routes visible via BGP.
If this condition is met then inject a default route into the OSPF
connected local network below.

So what would a changed metric give me?

Regards

Gerold