Cisco only has plans to support RSVP. Cisco and Juniper are looking at enhanced RSVP (eRSVP) for future development since it falls more in line with what has already been developed for IP. CR-LDP has more support from ATM vendors like Lucent, Nortel, Ericsson. It will be an issue in end-to-end label distribution when you cross from a IP-based MPLS network and an ATM-based MPLS network. In IP network with routers as the LERs/LSRs, the label is distributed in a MPLS shim header that gets created to "frame" the IP packet. In ATM networks, the label is the VPI/VCI values in the regular ATM cell header. So you can see the issue. Don't know for certain how the vendors plan on solving the label distribution problem at the boundaries of the IP core and ATM core. Juniper docs say they recommend tunneling LSPs in this case.
