North American Network Operators Group Date Prev | Date Next | Date Index | Thread Index | Author Index | Historical Re: Routing flaps, was Re: Ping flooding
On Fri, 12 Jul 1996, Paul Ferguson wrote: > I'm sorry, but I'm afraid that you're missing the point here. > > In most larger ISP backbones, the behavior of their IGP is indeed > visible to the public, since in most instances, most of the Internet > traffic relies on the stability of these interior (an esoteric term) > networks. Therefore, whether interior or exterior flap is really of > no relevance in this context. <This isn't intended to irritate, I just want to make sure I understand this correctly> Let me try a very simple example: To Internet To Internet <-- Peering points or upstreams 'Point A' 'Point B' | | +-----------+ +-----------+ | Router A |---| Router B | +-----------+ +-----------+ | | | | +-----------+ +-----------+ | Router C | | Router D | +-----------+ +-----------+ | | To Downstream To Downstream Non-BGP (Static) Non-BGP (Static) Customer Customer Routers A & B are running BGP to the outside world, and iBGP between them. Routers C & D are 'defaulted' into A and B. If the link between A&B dies the Exterior Routes will (and should) flap. If the link between either A or B and the Internet dies, the Exterior Routes will (and should) flap. If the line between routers A&C or B&D or between either C or D and their respective static downstreams die, there should be NO external route flap. However, if C&D are incapable of 'Null0' routing, it may be beneficial to run dynamic routing between A&C and between B&D so that A&B discard packets instead of causing a routing loop. This "internal routing flap" should not be visible to the outside world. I think that's what I meant to say before. Sometimes I'm not too clear about what I'm saying. If I've still missed the boat feel free to let me know :) [email protected] - - - - - - - - - - - - - - - - -
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