Interesting approach. So Fastly is offloading the full routing table to their carriers' router(s). That's because routers that can hold full BGP tables are expensive to purchase and maintain. But to retain some form of control, they're terminating eBGP at the switch and using iBGP to disseminate (inject) the providers' route (next hop).

I feel (I don't have direct experience with this setup) like they're just offloading some compute power (therefore cost) to the hosts. So the cost is automatically spread out across their relatively massive edge nodes. A line showing a router plus support costing $100,000 looks bad in expenditures vs showing a server plus integrated routing showing $2500.

I'm curious about how this impacts Varnish considering how table look ups can be bus-expensive during odd route changes/flaps (storms). %sys must go through the roof as a result.