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Last Modified: 2016-02-20
Route ( is advertised by BGP over multiple AS's to a router that NAT's ( -   Now is converted to a static route to null0 and advertised into BGP.  ONLY THE NEW ROUTE  - is allowed to propagate.  All other routes behind the NAT boundary are filtered.

#ip route null0
#router bgp 1200
#network mask

The problem:

The new route (  has no knowledge of the original route (

Is there any method such as IP SLA, specialized route maps or specialized TCL programs that would modify or remove the new route ( should an issue occur on the originating network that would prevent the original route of from making it to the NAT boundary.  

I would be interested in any mechanism that can confirm the health of the old route and when required block or modify the attributes of the new route.

Remember.... the issue is the fact that the original route is not allowed to propagate beyond the NAT boundary due to route filtering and instead only the new NAT induced route ( is advertised beyond the NAT boundary.  I am seeking some method of TRACKING the health of the original route or connectivity to the originating router so that should and issue occur then the new route would be modified.

Yes....this is a very challenging scenario///
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