If EL insertion is configured for a VPLS or VLL service, the MTU of the SDP binding is automatically reduced to account for the overhead of the EL and ELI labels. The MTU is reduced whether the LSP tunnel used by the service is entropy-label-capable.
The EL requires the insertion of two additional labels in the label stack. In some cases, the insertion of EL and ELI may result in an unsupported label stack depth or large changes in the label stack depth during the lifetime of an LSP. For RSVP LSPs, the entropy-label command under the config>router>mpls and config>router>mpls>lsp contexts provides local control at the head-end of an LSP over whether the entropy label is inserted on an LSP irrespective of the entropy label capability signaled from the egress LER, and control over how the additional label stack depth is accounted for. This control allows a user to avoid entropy label insertion where there is a risk of the label stack becoming too deep.