With BGP Confederations, why are the Confederation ASNs prepended to the AS Path discipline? From what I’ve learn, they aren’t used when figuring out the shortest path to any locations.
I may assume that this works as a Loop Prevention mechanism in order that BGP packets aren’t going backwards and forwards between the Confederations they’ve already handed, however there’s already a path attribute known as AS_CONFED_SEQ which is an ordered checklist of confederation ASNs the UPDATE packet traversed by way of.
So what can be the purpose of prepending the Confederation ASNs to the AS Path Area? Is there actually any use to it?
