Hi Gert, On 23/11/2009, at 5:46 PM, Gert Doering wrote:
> both ISP-Routers announce the ISP's aggregate (let's call it 200.1.0.0/16) > to their respective upstream providers (static route to null0, "network" > statement). This needs to be done, to make sure that the aggregate is > always visible, even if one of the routers is down. So you are generating the aggregate at the border? That can certainly leave you black holing traffic under several scenarios (anything that isolates that router). Have you thought about generating the aggregate within your network and propagating it via iBGP. At least the border can't advertise it upstream instantaneously as it won't know about it until iBGP is up. So either a static to NULL0 on a pair of core box somewhere or even an aggregate address statement on the border could help you here. Both should delay the advertisement of the aggregate upstream but I don't know if the timing of the advertisement would be deterministic. You could still have the same issue just for a shorter period. David ... _______________________________________________ cisco-nsp mailing list cisco-nsp@puck.nether.net https://puck.nether.net/mailman/listinfo/cisco-nsp archive at http://puck.nether.net/pipermail/cisco-nsp/
