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Versions: 00 01                                                         
MPLS Working Group                                          L. Andersson
Internet-Draft                                  Bronze Dragon Consulting
Intended status: Informational                            April 29, 2021
Expires: October 31, 2021


                    MPLS Open Design Team Questions
               draft-andersson-mpls-open-dt-questions-00

Abstract

   This document is a living document, meaning that during the life
   timme of the MPLS Open Design Team we will put additonal questions/
   issues into the document.  When we find an answer amd a way to
   document the issu it will be removed from this document.

   Ideally when the Design Team is closed this document will be empty,
   or maybe we just add a pointer to where the answer to quesstion is
   documented.  Thus this document will never go on to become an RFCc.

Status of This Memo

   This Internet-Draft is submitted in full conformance with the
   provisions of BCP 78 and BCP 79.

   Internet-Drafts are working documents of the Internet Engineering
   Task Force (IETF).  Note that other groups may also distribute
   working documents as Internet-Drafts.  The list of current Internet-
   Drafts is at https://datatracker.ietf.org/drafts/current/.

   Internet-Drafts are draft documents valid for a maximum of six months
   and may be updated, replaced, or obsoleted by other documents at any
   time.  It is inappropriate to use Internet-Drafts as reference
   material or to cite them other than as "work in progress."

   This Internet-Draft will expire on October 31, 2021.

Copyright Notice

   Copyright (c) 2021 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

   This document is subject to BCP 78 and the IETF Trust's Legal
   Provisions Relating to IETF Documents
   (https://trustee.ietf.org/license-info) in effect on the date of
   publication of this document.  Please review these documents
   carefully, as they describe your rights and restrictions with respect
   to this document.  Code Components extracted from this document must



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   include Simplified BSD License text as described in Section 4.e of
   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
     1.1.  Requirement Language  . . . . . . . . . . . . . . . . . .   2
   2.  Open DT Question List . . . . . . . . . . . . . . . . . . . .   3
     2.1.  Below the BoS . . . . . . . . . . . . . . . . . . . . . .   3
       2.1.1.  Limitations to the ability of LSR's to scan the Label
               Stack . . . . . . . . . . . . . . . . . . . . . . . .   3
       2.1.2.  Does flooding om maximum scanning depth of an LSR
               scale?  . . . . . . . . . . . . . . . . . . . . . . .   3
       2.1.3.  Does flooding om maximum scanning depth of an LSR
               scale?  . . . . . . . . . . . . . . . . . . . . . . .   3
       2.1.4.  First Nibble  . . . . . . . . . . . . . . . . . . . .   3
       2.1.5.  More then on ACH after the bBoS . . . . . . . . . . .   4
       2.1.6.  More then one indicator?  . . . . . . . . . . . . . .   4
     2.2.  Above the BoS . . . . . . . . . . . . . . . . . . . . . .   4
       2.2.1.  Resuse the ELI  . . . . . . . . . . . . . . . . . . .   4
   3.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   4
   4.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .   4
   5.  Normative References  . . . . . . . . . . . . . . . . . . . .   4
   Author's Address  . . . . . . . . . . . . . . . . . . . . . . . .   4

1.  Introduction

   "Living Documents" are not commonly used in the IETF, but we have
   considered it to be a good way of documenting the state of the issues
   worked on by the design team.

1.1.  Requirement Language

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
   "OPTIONAL" in this document are to be interpreted as described in BCP
   14 [RFC2119] [RFC8174] when, and only when, they appear in all
   capitals, as shown here.

   For a document that is not intended to become and RFC on the
   Standards Track it might seem moot to have the requirement language
   included, however it might be that a question or an answer to one of
   the questions might use the BCP 14 language, so to avoid ambiguity we
   left it in






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2.  Open DT Question List

2.1.  Below the BoS

   As we start working on this document we just add new questions as we
   define them.  It is possible that later we will try to find a
   grouping af questions based more on technical commonalities.

2.1.1.  Limitations to the ability of LSR's to scan the Label Stack

   Several LSRs have limitations how deep it is possible to scan the
   label stack looking for certain information.  If the info that are
   being looked for is below this depth, is it possible to use these
   LSRs for manadatoy actions?

   The inormation needed for the mandatory action will never be found.

2.1.2.  Does flooding om maximum scanning depth of an LSR scale?

   A remedy for the issues in Section 2.1.1 has been suggested, the
   maaximum scanning depth for each LSR in the network should be flooded
   to all othr LSRs and used as a constraint when setting up LSPs.

   Would that scasle satisfactorily.

2.1.3.  Does flooding om maximum scanning depth of an LSR scale?

   A remedy for the issues in Section 2.1.1 has been suggested, the
   maaximum scanning depth for each LSR in the network should be flooded
   to all othr LSRs and used as a constraint when setting up LSPs.

   Would that scale satisfactorily.

2.1.4.  First Nibble

   We have indications that when we started to snoop the first nibble
   after the LSE that has the BoS set to find out if the packet carried
   IP (v4 or v6), there was also an agreement that "we" would never put
   anything but 0b0000 or 0b0001 in that first nibble.

   It is off couurse intresting to try to understand the definition of
   "we" but since the aggreement were between the Internet Area and the
   PWE3 working group, it is likely that it will be considered binding
   for the Routing Area.

   Stewart: Can you try to find out more about this and where we stand
   today.




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2.1.5.  More then on ACH after the bBoS

   More than one ACH after the BoS.  How are the ACH's separated and
   related to the indicator in the label stack?

2.1.6.  More then one indicator?

   5.  What happens when you find the first indicator?  If an LSR is
   scanning "the entire stack", what happens when the first indicator is
   found?

2.2.  Above the BoS

   -

2.2.1.  Resuse the ELI

   -

3.  IANA Considerations

   This document does not make any allocations of code points from IANA
   registries.

4.  Acknowledgements

   -

   -

5.  Normative References

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119,
              DOI 10.17487/RFC2119, March 1997,
              <https://www.rfc-editor.org/info/rfc2119>.

   [RFC8174]  Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
              2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
              May 2017, <https://www.rfc-editor.org/info/rfc8174>.

Author's Address

   Loa Andersson
   Bronze Dragon Consulting

   Email: loa@pi.nu




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