[j-nsp] BGP route announcements and Blackholes

[Lee Starnes]

Hello Juniper gurus. I am seeing an issue where we have a carrier that does
RTBH via BGP announcement rather than community strings. This is done via
BGP peer to a blackhole BGP router/server.

My issue here is that our aggregate IP block that is announced to our
backbone providers gets impacted when creating a /32 static discard route
to announce to that blackhole peer.

The blackhole peer does receive the /32 announcement, but the aggregate
route also becomes discarded and thus routes to the other peers stop
working.

Been trying to determine just how to accomplish this function without
killing all routes.

So we have several /30 to /23 routes within our /19 block that are
announced via OSPF from our switches to the routers. The routers aggregate
these to the /19 to announce the entire larger block to the backbone
providers.

The blackhole peer takes routes down to a /32 for mitigation of an attack.
If we add a static route as "route x.x.22.12/32 discard" we get:

show route x.x.22.10

inet.0: 931025 destinations, 2787972 routes (931025 active, 0 holddown, 0
hidden)
@ = Routing Use Only, # = Forwarding Use Only
+ = Active Route, - = Last Active, * = Both

x.x.0.0/19     *[OSPF/125] 5d 19:26:19, metric 20, tag 0
                    >  to 10.20.20.3 via ae0.0
                    [Aggregate/130] 5d 20:18:36
                       Reject


While we see the more specific route as discard:

show route x.x.22.12

inet.0: 931022 destinations, 2787972 routes (931022 active, 0 holddown, 0
hidden)
@ = Routing Use Only, # = Forwarding Use Only
+ = Active Route, - = Last Active, * = Both
x.x.22.12/32    *[Static/5] 5d 20:20:07
                       Discard



Does anyone have a working config for this type of setup that might be able
to share some tips or the likes on what I need to do or what I'm doing
wrong?

Best,

-Lee