The router supports both the MPLS entropy label, as specified in RFC 6790, and the flow-aware transport (FAT) label (the FAT label is also known as the hash label), as specified in RFC 6391. LSR nodes in a network can load-balance labeled packets in a more granular way than by hashing on the standard label stack by demarking the presence of individual flows on the LSP. The labels also remove the need to have an LSR inspect the payload below the label stack and check for an IPv4 or IPv6 header to determine how to apply load balancing.
The hash label is primarily applicable to Layer 2 services such as VLL and VPLS, while the entropy label (EL) is applicable to more general scenarios where a common way to indicate flows on a wide range of services suitable for load balancing is required.
The application of a hash label or an entropy label is mutually exclusive for a service.