draft-ietf-mpls-spl-terminology-02.txt   draft-ietf-mpls-spl-terminology-03.txt 
MPLS Working Group L. Andersson MPLS Working Group L. Andersson
Internet-Draft Bronze Dragon Consulting Internet-Draft Bronze Dragon Consulting
Updates: 3032, 7274 (if approved) K. Kompella Updates: 3032, 7274 (if approved) K. Kompella
Intended status: Informational Juniper Networks Intended status: Informational Juniper Networks
Expires: November 6, 2020 A. Farrel Expires: February 13, 2021 A. Farrel
Old Dog Consulting Old Dog Consulting
May 5, 2020 August 12, 2020
Special Purpose Label terminology Special Purpose Label terminology
draft-ietf-mpls-spl-terminology-02 draft-ietf-mpls-spl-terminology-03
Abstract Abstract
This document discusses and recommends a terminology that may be used This document discusses and recommends a terminology that may be used
when MPLS Special Purpose Labels (SPL) are specified and documented. when MPLS Special Purpose Labels (SPL) are specified and documented.
This document updates RFC 7274 and RFC 3032. This document updates RFC 7274 and RFC 3032.
Status of This Memo Status of This Memo
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Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet- working documents as Internet-Drafts. The list of current Internet-
Drafts is at https://datatracker.ietf.org/drafts/current/. Drafts is at https://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress." material or to cite them other than as "work in progress."
This Internet-Draft will expire on November 6, 2020. This Internet-Draft will expire on February 13, 2021.
Copyright Notice Copyright Notice
Copyright (c) 2020 IETF Trust and the persons identified as the Copyright (c) 2020 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents Provisions Relating to IETF Documents
(https://trustee.ietf.org/license-info) in effect on the date of (https://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents publication of this document. Please review these documents
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7. References . . . . . . . . . . . . . . . . . . . . . . . . . 5 7. References . . . . . . . . . . . . . . . . . . . . . . . . . 5
7.1. Normative References . . . . . . . . . . . . . . . . . . 5 7.1. Normative References . . . . . . . . . . . . . . . . . . 5
7.2. Informative References . . . . . . . . . . . . . . . . . 5 7.2. Informative References . . . . . . . . . . . . . . . . . 5
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 6 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 6
1. Introduction 1. Introduction
RFC 7274 [RFC7274] made some changes to the terminology used for MPLS RFC 7274 [RFC7274] made some changes to the terminology used for MPLS
Special Purpose Labels, but did not define consistent terminology. Special Purpose Labels, but did not define consistent terminology.
One thing that RFC 7274 did was to deprecate use use of the term One thing that RFC 7274 did was to deprecate use of the term
"reserved labels" when describing a range of labels allocated from a "reserved labels" when describing a range of labels allocated from a
registry maintained by IANA. The term "Reserved" in such a registry registry maintained by IANA. The term "Reserved" in such a registry
means "set aside, not to be used", but that range of labels was means "set aside, not to be used", but that range of labels was
available for allocation according to the policies set out in the available for allocation according to the policies set out in that
registry. The name "Special Purpose Labels" was introduced in RFC registry. The name "Special Purpose Labels" was introduced in RFC
7274 in place of the previous term, and the abbreviation SPL was 7274 in place of the previous term, and the abbreviation SPL was
recommended. recommended.
At the time of writing the first version of this document, the IETF At the time of writing the first version of this document, the IETF
was in the process of allocating the very first SPLs from the was in the process of allocating the very first SPLs from the
Extended SPL range [RFC8595]. This document discusses and recommends Extended SPL (eSPL) range [RFC8595]. This document discusses and
terminology and abbreviations to be used when talking about and recommends terminology and abbreviations to be used when talking
documenting Special Purpose Labels. about and documenting Special Purpose Labels.
This document updates RFC 3032 [RFC3032] and RFC 7274 [RFC7274] and This document updates RFC 3032 [RFC3032] and RFC 7274 [RFC7274] in
RFC 3032 [RFC3032] in that it changes the terminology for both Base that it changes the terminology for both Base SPLs and Extended SPLs.
SPLs and Extended SPLs.
2. Background 2. Background
Two sets of SPLs are defined for use in MPLS: Two sets of SPLs are defined for use in MPLS:
The range of SPLs 0-15 is specified in RFC 3032 [RFC3032]. The range of 0-15, Base Special Purpose Labels (bSPLs), is
specified in RFC 3032 [RFC3032].
The range of SPLs 0-1048575 is specified in RFC 7274 [RFC7274]. The range 0-1048575 of eSPLs is specified in RFC 7274 [RFC7274].
* the values 0-15 has been reserved never to be allocated * the values 0-15 have been reserved never to be allocated
* the values 15-239 are available for allocation * the values 16-239 are available for allocation
* the values 240-255 are for experimental use * the values 240-255 are for experimental use
* the values 256-1048575 are currently not available for * the values 256-1048575 are currently not available for
allocation, and a standard tracks RFC will be needed to make allocation. A standard track RFC will be needed to allocate
the entire range or part of it available for allocation any labels from this range.
2.1. GMPLS Special Purpose Labels 2.1. GMPLS Special Purpose Labels
Note that IANA maintains a registry called "Special Purpose Note that IANA maintains a registry called "Special Purpose
Generalized Label Values". Labels in that registry have special Generalized Label Values". Labels in that registry have special
meaning when present in certain signalling objects, are 32 bits long, meaning when present in certain signalling objects, are 32 bits long,
and are not to be confused with MPLS forwarding plane labels. This and are not to be confused with MPLS forwarding plane labels. This
document does not make any changes to the registry or how labels from document does not make any changes to the GMPLS registry or to how
that registry are described. labels from that registry are described.
3. Terminology and Abbreviations 3. Terminology and Abbreviations
IANA maintains a name space for 'Special-Purpose Multiprotocol Label IANA maintains a name space for 'Special-Purpose Multiprotocol Label
Switching (MPLS) Label Values' code points [SPL-NAME-SPACE]. Within Switching (MPLS) Label Values' code points [SPL-NAME-SPACE]. Within
this name space there are two registries. One is called the this name space there are two registries. One is called the
'Special-Purpose MPLS Label Values' registry [bSPL]. The other is 'Special-Purpose MPLS Label Values' registry [bSPL]. The other is
called 'Extended Special-Purpose MPLS Label Values' registry [eSPL]. called 'Extended Special-Purpose MPLS Label Values' registry [eSPL].
The difference in the name of the name space and the first registry The difference in the name of the name space and the first registry
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o Collectively, the two ranges are known as Special Purpose Labels o Collectively, the two ranges are known as Special Purpose Labels
(SPL). (SPL).
o The special purpose labels from the lower range will be called o The special purpose labels from the lower range will be called
Base Special Purpose Labels (bSPL). Base Special Purpose Labels (bSPL).
o The special purpose labels from the higher range will be called o The special purpose labels from the higher range will be called
Extended Special Purpose Labels (eSPL). Extended Special Purpose Labels (eSPL).
o The combination of the Extension Label (XL) (value 15 which is an o The combination of the Extension Label (XL) (value 15 which is a
bSPL, but that is also called xSPL) and an eSPL is called a bSPL, but that is also called xSPL) and an eSPL is called a
Composite Special Purpose Label (cSPL). Composite Special Purpose Label (cSPL).
This results in a label stacks such as the illustrative examples This results in a label stacks such as the illustrative examples
shown in Figure 1 and Figure 2. shown in Figure 1 and Figure 2.
0 31 0 31
| MPLS Label Stack entry | | MPLS Label Stack entry |
+--------+--------+--------+--------+ +--------+--------+--------+--------+
| MPLS Label Stack entry | | MPLS Label Stack entry |
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xSPL | Extension Label (XL) | <--+ xSPL | Extension Label (XL) | <--+
+--------+--------+--------+--------+ |--- cSPL +--------+--------+--------+--------+ |--- cSPL
eSPL | Extended SPL | <--+ eSPL | Extended SPL | <--+
+--------+--------+--------+--------+ +--------+--------+--------+--------+
| MPLS Label Stack entry (cont.) | | MPLS Label Stack entry (cont.) |
Figure 2: Example of Label Stack Figure 2: Example of Label Stack
4. Security Considerations 4. Security Considerations
This document is entirely about terminology for SPLs and does not The document describes the terminology to be used when describing and
effect the forwarding in the MPLS data plane, nor does it have any specifying the use of SPLs. It does not effect the forwarding in the
effect on how LSPs are establsihed by an MPLS control plane or by a MPLS data plane, nor does it have any effect on how LSPs are
centralized controller. The doucment describes a terminology to be established by an MPLS control plane or by a centralized controller.
used when describing and specifying the use of SPLs.
This document does not aim to describe existing implementations of This document does not aim to describe existing implementations of
SPLs or the potential vulnerabilities of SPLs. SPLs or potential vulnerabilities of SPLs.
5. IANA Considerations 5. IANA Considerations
We request that the name of the IANA registry that today is called We request that the name of the IANA registry that today is called
"Special-Purpose MPLS Label Values" is changed to "Base Special- "Special-Purpose MPLS Label Values" is changed to "Base Special-
Purpose MPLS Label Values". Purpose MPLS Label Values".
6. Acknowledgements 6. Acknowledgements
The authors of this document would like to thank Stewart Bryant for The authors of this document would like to thank Stewart Bryant for
careful review and constructive suggestions. careful review and constructive suggestions.
We would also like to thank the Routing Directorate reviwer Eric Gray
for a detailed, careful and insightful review.
7. References 7. References
7.1. Normative References 7.1. Normative References
[bSPL] "Special-Purpose MPLS Label Values", [bSPL] "Special-Purpose MPLS Label Values",
<https://www.iana.org/assignments/mpls-label-values/mpls- <https://www.iana.org/assignments/mpls-label-values/mpls-
label-values.xhtml#special-purpose/>. label-values.xhtml#special-purpose/>.
[eSPL] "Extended Special-Purpose MPLS Label Values", [eSPL] "Extended Special-Purpose MPLS Label Values",
<https://www.iana.org/assignments/mpls-label-values/mpls- <https://www.iana.org/assignments/mpls-label-values/mpls-
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