Allocating and Retiring Special-Purpose MPLS Labels (RFC7274)
Original Publication Date: 2014-Jun-01
Included in the Prior Art Database: 2014-Jun-13
Internet Society Requests For Comment (RFCs)
K. Kompella: AUTHOR [+3]
The MPLS Label Stack Encoding specification [RFC3032] defined four special-purpose label values (0 to 3) and set aside values 4 through 15 for future use. These labels have special significance in both the control and the data plane. Since then, three further values have been allocated (values 7, 13, and 14 in [RFC6790], [RFC5586], and [RFC3429], respectively), leaving nine unassigned values from the original space of sixteen.
Internet Engineering Task Force (IETF) K. Kompella Request for Comments: 7274 Juniper Networks Updates: 3032, 3038, 3209, 3811, 4182, 4928, 5331, L. Andersson 5586, 5921, 5960, 6391, 6478, 6790 Huawei Category: Standards Track A. Farrel ISSN: 2070-1721 Juniper Networks June 2014
Allocating and Retiring Special-Purpose MPLS Labels
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.
Status of This Memo
This is an Internet Standards Track document.
This document is a product of the Internet Engineering Task Force (IETF). It represents the consensus of the IETF community. It has received public review and has been approved for publication by the Internet Engineering Steering Group (IESG). Further information on Internet Standards is available in Section 2 of RFC 5741.
Information about the current status of this document, any errata, and how to provide feedback on it may be obtained at http://www.rfc-editor.org/info/rfc7274.
al. Standards Track [Page 1]
RFC 7274 Special-Purpose MPLS Labels June 2014
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