While deploying multicast in a single domain is now well understood, things are not so well defined in the inter-domain case. Moreover different problems and solutions are different for ASM and SSM and whether we consider IPv4 or IPv6. In this section we consider only PIM-SMv2 as the protocol for building multicast trees, since this is the only protocol that is both available and usable in interdomain. In next section we present the inter-domain solutions for the ASM case and then for the SSM case.