nk. For multicast addresses, there are various scopes defined by RFC 4007 and others. For any constrained scope, a system must establish a (potentially one-to-many) mapping between zones and local interfaces. For example, a link-local address is valid on only one link (its zone). That link may be attached to one or more local interfaces. The decisions on which scopes are constrained and the mapping between zones and interfaces is together what we refer to as the "scoping policy" - more on this in a bit.</p>