For a service to stay reachable no matter what, internet access alone isn't enough: you need several carriers, controlled routing and, often, your own AS number. That's the role of IP transit and BGP.
Design & price my architecture →IP transit is the access that carries your traffic to the whole internet. BGP is the protocol that, via your AS number and prefixes, lets you announce your addresses through several carriers at once — for resilience and independence.
If you want independence from a carrier and multi-transit or multi-site, yes: an AS and provider-independent (PI) addresses make you portable. DataColoc advises on the real need.
Transit carries to the whole internet (paid by bandwidth); peering exchanges traffic directly with other networks at an IXP (often cheaper). Both are combined.
At least two for resilience, ideally geo-redundant. Sizing depends on criticality and budget.
Design & price my architecture → Compare data centers