A Survey to Determine MPLS Label Stack Inspection Behavior

As part of the work on MPLS Network Actions (MNA) a debate arose concerning how existing MPLS implementations handle Special Purpose Labels (SPLs) especially in the context of processing the MPLS Entropy Label. The question applies to the relative placement of the Entropy Label Indicator (ELI) and the MNA Base SPL in the MPLS label stack. This question is applicable to the use of the ELI and any new base SPL (bSPL), or to the relative placement of any two bSPLs including the Extension Label that precedes any extended SPL. In order to discover what deployed implementations currently do, it is proposed that the MPLS working group chairs poll participants to answer specific questions about their implementations. This document is a working draft of the questions to be asked. It is not intended that this document should progress to publication as an RFC.