On 9/29/23 22:56, William Herrin wrote:
Actually, BGP can swing that. Routing involves two distinct components: the routing information base (RIB) and the forwarding information base (FIB). BGP is part of the RIB portion of that process. It's always implemented in software (no hardware acceleration). It's not consulted per-packet, so as long as the update rate is slow enough for the CPU to keep up and there's enough DRAM (which is cheap and plentiful these days) to hold the entire thing, there's no particular upper bound to the number of routes.
Not unless you are running BGP Add-Paths in its extreme guise to consider all available paths, and then there is the chance you could push your RAM and CPU into unknown territory, depending on the platform, code and control plane you've got.
The limiting factor is the FIB. The FIB is what is implemented with hardware acceleration on high-end routers in order to achieve large packet-per-second (PPS) numbers. It relies on storage hardware which is both faster and more expensive than DRAM. Consequently it has much less capacity to store information than DRAM. Currently shipping equipment intended for BGP backbone use can manage 1M to 2M routes in the hardware-accelerated FIB regardless of the amount of DRAM on the machine.
There are line cards out there today that are able to hold 10 million routes in FIB.
Mark.
