Convergence platform:

Thought on where we can go on indicators. This text does not address ancillary data, where it is placed and how it is encoded.

The design team agrees on the following:

  • We want to limit the number of new assignments of base special purpose labels (bSPLs) as much as possible.
  • We have a standardized associated channel, the GAL/GACH. We are not going to change the associated channel in anyway that breaks existing implementations. The ACH is found immediately after the label carrying the Bottom of Stack (BoS) bit. Currently, there is no defined method to carry multiple ACHs in the same MPLS packet. GAL/GACH will only be an OAM or instrumentation tool and will not be used to carry meta-data with user-traffic.

  • Any new mechanism to carry meta-data needs to have a well defined method of handling types/versions that are not understood or supported by a receiving router.
  • We need a mechanism to indicate presence of meta-data or actions on an MPLS packet. We therefore need an in-stack method to serve this purpose. Any in-stack method is in scope.
  • One proposal is to "re-purpose" an existing bSPL to serve this purpose. However, in order to do this it must be shown that there is no potential interference with the current role of the bSPL.

  • If we can't demonstrate the non-interference then we should assign specific forwarding action indicator base special purpose label.
  • Multiple actions may need to be indicated by the same bSPL.
  • The coexistence of OAM mechanisms and ancillary data encodings needs to be designed in the new mechanism.
Last modified 10 months ago Last modified on 22/07/21 16:13:42