I've just lodged a request with upstream to clarify some specifics of their recommended BGP configuration. Currently, I will be dual-homing with my upstream via PI addresses. Advertising via BGP with my own AS, and have requested they pass me a default route.
Their recommended configuration is to have two cross-connects, one from each of my primary/secondary router, connecting to their primary/secondary router, respectively. My primary would their peer with their primary, and my secondary with theirs. This is all fine (aside from the potential no-connectivity scenario if my primary is down, and their secondary is down).
But my confusion is this: My provider is suggesting that by taking only a default, I am going to have an active/standy configuration, and that I need a full set of routes for active/active.
My understanding was that if I'm only homed via a single ISP, then a full-feed becomes effectively pointless, since all traffic is going the same path either way. What am I missing that would cause this to be an active/standy configuration? Surely the secondary router, if traffic hits it, is going to prefer to send out it's local default gateway, as opposed to first sending traffic to the primary?
Taking it from another perspective, I can't see how full routes is going to change the behavior (ignoring possible traffic engineering scenarios), since both routers would have the same set of routes from upstream.