Applying TIE in a Separate Path-Selection Platform

Rather than modifying the BGP decision process implemented on the routers, an AS could move the entire responsibility for BGP path selection to a separate software platform, as proposed in [20,21]. In this setting, dedicated servers receive the eBGP advertisements and run decision logic to select BGP routes on behalf of the routers in the AS. The servers use iBGP sessions to send each router a customized routing decision for each prefix, essentially overriding the influence of the BGP decision process running on the routers.

These servers could implement the TIE mechanism for selecting the routes in real time, and might also run the offline optimization routines that set the $\alpha$ and $\beta$ parameters; this would allow the parameters to exist only on the servers, rather than in the routers or other management systems. Even though the servers could conceivably implement any decision logic, in practice they need some separation of functionality between the real-time adaptation to network events and the longer-term optimization of the path-selection process based on network-wide goals. TIE provides a way to achieve that separation.