draft-ietf-mpls-spl-terminology-04.txt   draft-ietf-mpls-spl-terminology-05.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: Standards Track Juniper Networks Intended status: Standards Track Juniper Networks
Expires: March 28, 2021 A. Farrel Expires: May 19, 2021 A. Farrel
Old Dog Consulting Old Dog Consulting
September 24, 2020 November 15, 2020
Special Purpose Label terminology Special Purpose Label terminology
draft-ietf-mpls-spl-terminology-04 draft-ietf-mpls-spl-terminology-05
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 applies that terminology change to the relevant IANA This document applies that terminology change to the relevant IANA
registry and also clarifies the use of the Entropy Label Indicator registry and also clarifies the use of the Entropy Label Indicator
(7) when immediately preceded by the Extension Label (15). (7) when immediately preceded by the Extension Label (15).
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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 March 28, 2021. This Internet-Draft will expire on May 19, 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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the Trust Legal Provisions and are provided without warranty as the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License. described in the Simplified BSD License.
Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
1.1. Terminology . . . . . . . . . . . . . . . . . . . . . . . 3 1.1. Terminology . . . . . . . . . . . . . . . . . . . . . . . 3
2. Background . . . . . . . . . . . . . . . . . . . . . . . . . 3 2. Background . . . . . . . . . . . . . . . . . . . . . . . . . 3
2.1. GMPLS Special Purpose Labels . . . . . . . . . . . . . . 3 2.1. GMPLS Special Purpose Labels . . . . . . . . . . . . . . 3
3. Terminology and Abbreviations . . . . . . . . . . . . . . . . 3 3. Terminology and Abbreviations . . . . . . . . . . . . . . . . 3
4. Clarification on Use of Entropy Label Indicator . . . . . . . 5 4. Clarification on Handling of the Entropy Label Indicator . . 5
5. Security Considerations . . . . . . . . . . . . . . . . . . . 6 5. Security Considerations . . . . . . . . . . . . . . . . . . . 6
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 6 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 6
7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 6 7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 6
8. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 6 8. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 6
9. References . . . . . . . . . . . . . . . . . . . . . . . . . 7 9. References . . . . . . . . . . . . . . . . . . . . . . . . . 7
9.1. Normative References . . . . . . . . . . . . . . . . . . 7 9.1. Normative References . . . . . . . . . . . . . . . . . . 7
9.2. Informative References . . . . . . . . . . . . . . . . . 7 9.2. Informative References . . . . . . . . . . . . . . . . . 7
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 7 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 7
1. Introduction 1. Introduction
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| MPLS Label Stack entry | | MPLS Label Stack entry |
+--------+--------+--------+--------+ +--------+--------+--------+--------+
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. Clarification on Use of Entropy Label Indicator 4. Clarification on Handling of the Entropy Label Indicator
Section 3.1 of [RFC7274] contains two paragraphs that describe the Section 3.1 of [RFC7274] contains two paragraphs that describe the
use of the Entropy Label Indicator (label 7). These paragraphs have handling of the Entropy Label Indicator (label 7). These paragraphs
introduced some confusion about whether the Entropy Label Indicator have introduced some confusion about whether the Entropy Label
can be present when immediately preceded by the Extension Label. Indicator can be present when immediately preceded by the Extension
This document updates [RFC7274] by replacing those paragraphs as Label. This document updates [RFC7274] by replacing those paragraphs
follows. as follows.
OLD OLD
Values 0-15 of the "Extended Special-Purpose MPLS Label Values" Values 0-15 of the "Extended Special-Purpose MPLS Label Values"
registry are set aside as reserved. Furthermore, values 0-6 and registry are set aside as reserved. Furthermore, values 0-6 and
8-15 MUST NOT appear in the data plane following an XL; an LSR 8-15 MUST NOT appear in the data plane following an XL; an LSR
processing a packet with an XL at the top of the label stack processing a packet with an XL at the top of the label stack
followed by a label with value 0-6 or 8-15 MUST drop the packet. followed by a label with value 0-6 or 8-15 MUST drop the packet.
Label 7 (when received) retains its meaning as Entropy Label Label 7 (when received) retains its meaning as Entropy Label
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registry are set aside as reserved. Furthermore, an registry are set aside as reserved. Furthermore, an
implementation MUST NOT place a label with value 0-15 in the label implementation MUST NOT place a label with value 0-15 in the label
stack immediately following an XL; an LSR processing a packet with stack immediately following an XL; an LSR processing a packet with
an XL at the top of the label stack immediately followed by a an XL at the top of the label stack immediately followed by a
label with value 0-15 MUST drop the packet. label with value 0-15 MUST drop the packet.
When inspecting a label stack to find an Entropy Label Indicator When inspecting a label stack to find an Entropy Label Indicator
(ELI - label 7) a pre-existing implementation may fail to inspect (ELI - label 7) a pre-existing implementation may fail to inspect
the previous label, and so not notice that it is an XL. Such the previous label, and so not notice that it is an XL. Such
systems can continue to process the entropy information and systems can continue to process the entropy information and
forward the packet when the previous label is an XP without forward the packet when the previous label is an XL without
causing harm. However, the packet will be dropped when the XL causing harm. However, the packet will be dropped when the XL
reaches the top of the stack at another LSR. reaches the top of the stack at another LSR.
END END
5. Security Considerations 5. Security Considerations
The document describes the terminology to be used when describing and The document describes the terminology to be used when describing and
specifying the use of SPLs. It does not effect the forwarding in the specifying the use of SPLs. It does not effect the forwarding in the
MPLS data plane, nor does it have any effect on how LSPs are MPLS data plane, nor does it have any effect on how LSPs are
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