1. Create an import policy in which you only accept a subset of received route and install them in the routing-table. 2. Create an conditional default-route (generate route) and apply condition with the route.
root@CE1_re# set policy-options policy-statement if-bgp term 1 from protocol bgp  root@CE1_re# set policy-options policy-statement if-bgp term 1 then accept  root@CE1_re# set policy-options policy-statement if-bgp term 1 then next-hop 10.1.0.1  root@CE1_re# set policy-options policy-statement if-bgp term 2 then reject  root@CE1_re# set routing-options generate route 0/0 policy if-bgp 
root@CE1_re# run show route 0/0 inet.0: 40 destinations, 42 routes (40 active, 0 holddown, 0 hidden)
+ = Active Route, - = Last Active, * = Both
0.0.0.0/0 *[Aggregate/130] 00:00:05 > to 10.1.0.1 via ge-0/0/2.0
If I deactivate the bgp, default route disappear.
 root@CE1_re# deactivate protocols bgp
 root@CE1_re# commit commit complete root@CE1_re# run show route
inet.0: 15 destinations, 15 routes (14 active, 0 holddown, 1 hidden) + = Active Route, - = Last Active, * = Both
10.0.0.0/8 *[Static/5] 4d 21:20:28 > to 10.x.x.x via fxp0.0 10.1.0.0/31 *[Direct/0] 4d 20:59:30 > via ge-0/0/2.0
In this is use case, the unique solution is that the ISP do the summarization of routes.
In fact, the solution that have been given need the import of the routes advertised by the ISP and after that create a default route ( or you summarize the routes). Those solutions can be good for the routers in your backbone but not for the edge router ( and as I understand, the mean problem that the edge router has not enough capacity)
As an ISP connecting a customer with BGP there are typically the following options as standard across the industry.
Full tables (your current option)
partial tables (a subset of the internet routes closely connected to your direct ISP)
default route (this can be alone or in combination with full / partial tables)
Full tables would generally be used if you are multi homed and want to mix the routing tables of your multiple ISPs yourself and create your own upstream mix. As you saw this requires a beefy router to accomadate the route table sizes today.
Partial tables would generally be used along with the default route if you are multihomed and you want to use the closely connected routes from both ISP and then pick one of them as the default with the other as the backup. This is a much smaller route table and most devices can handle it.
Default only recieves the default route only from each ISP and you use local preference or ECMP yourself to direct the traffic.
From your description, all you need to do is open a change control ticket with your ISP on your BGP service and request the change from full tables to either default only.
Steve Puluka BSEET - Juniper Ambassador IP Architect - DQE Communications Pittsburgh, PA (Metro Ethernet & ISP) http://puluka.com/home