We have BGP between our network and our customers networks and so far each connection uses private AS numbers (on our end we use a different AS number for each connection)
We recently got a public AS number for a connection to a provider. Now that we have this public AS number, should we be using that internally between our own routers (i.e. when deploying new BGP sessions between devices etc) - or should we continue using Private AS numbers?
From what I would gather, we would use the one AS number (our public AS number) to represent our organisation (internally between our routers and externally) where we can (and this would be the public AS number). Is this correct/best practice?
I had a quick look at RFC 1930 which states:
The classic definition of an Autonomous System is a set of routers under a single technical administration, using an interior gateway protocol and common metrics to route packets within the AS, and using an exterior gateway protocol to route packets to other ASes. Since this classic definition was developed, it has become common for a single AS to use several interior gateway protocols and sometimes several sets of metrics within an AS. The use of the term Autonomous System here stresses the fact that, even when multiple IGPs and metrics are used, the administration of an AS appears to other ASes to have a single coherent interior routing plan and presents a consistent picture of what networks are reachable through it. To rephrase succinctly: An AS is a connected group of one or more IP prefixes run by one or more network operators which has a SINGLE and CLEARLY DEFINED routing policy.