Allocating and Retiring Special-Purpose MPLS Labels, June 2014
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- PROPOSED STANDARD
- RFC 3032, RFC 3038, RFC 3209, RFC 3811, RFC 4182, RFC 4928, RFC 5331, RFC 5586, RFC 5921, RFC 5960, RFC 6391, RFC 6478, RFC 6790
- K. Kompella
- mpls (rtg)
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Some MPLS labels have been allocated for specific purposes. A block of labels (0-15) has been set aside to this end; these labels are commonly called "reserved labels". They will be called "special-purpose labels" in this document.
As there are only 16 of these special-purpose labels, caution is needed in the allocation of new special-purpose labels; yet, at the same time, forward progress should be allowed when one is called for.
This memo defines new procedures for the allocation and retirement of special-purpose labels, as well as a method to extend the special-purpose label space and a description of how to handle extended special-purpose labels in the data plane. Finally, this memo renames the IANA registry for special-purpose labels to "Special-Purpose MPLS Label Values" and creates a new registry called the "Extended Special-Purpose MPLS Label Values" registry.
This document updates a number of previous RFCs that use the term "reserved label". Specifically, this document updates RFCs 3032, 3038, 3209, 3811, 4182, 4928, 5331, 5586, 5921, 5960, 6391, 6478, and 6790.
For the definition of Status, see RFC 2026.
For the definition of Stream, see RFC 4844.