The service label per next-hop mode has the following restrictions (applies only to the 7750 SR):
ECMP — The VPRN label mode should be set to VRF if distribution of traffic across the multiple PE-CE next-hop interfaces of an ECMP route is desired.
Hub and spoke VPN — The VPRN label mode should not be set to next-hop if the operator does not want the hub-connected CE to be involved in the forwarding of spoke-to-spoke traffic.
BGP next-hop indirection — BGP next-hop indirection has no benefit in service label per next-hop mode. When the resolved next-hop interface of a BGP next-hop changes all of the affected BGP routes must be re-advertised to VPRN peers with the new service label corresponding to the new resolved next-hop.
BGP anycast — When a PE failure results in redirection of MPLS packets to the other PE in a dual-homed pair, the service label mode is forced to VRF, for example, FIB lookup will determine the next-hop even if the label mode of the VPRN is configured as next-hop.
U-turn routing — U-turn routing is effectively disabled by service-label per next-hop.
Carrier Supporting Carrier — The label-mode configuration of a VPRN with CSC interfaces is ignored for BGP-3107 routes learned from connected CSC-CE devices.