We have a headquarters location where we currently use BGP to multihome to two Internet providers. We have a /16 IP network. We run an active/standby scenario, where the less preferred Internet connection gets used only if the preferred one fails. We will be adding a disaster recovery site at a different location.
1. Can we add the DR site, configuring it to be the least preferred BGP path such that it gets used only if both connections at the headquarters site fail?
2. Can we advertise a specific subnet of the /16, such that traffic for the subnet always gets routed to the DR site, but the rest of the /16 gets routed to headquarters, unless headquarters fails, in which case all traffic goes to the DR site?