Subject: Protocol Action: 'Multi-Protocol Label Switching (MPLS) label stack entry: "EXP" field renamed to "Traffic Class" field' to Proposed Standard

From: The IESG <[email-masked]>
Date: Mon, 22 Dec 2008 12:27:01 -0800 (PST)

The IESG has approved the following document:

- 'Multi-Protocol Label Switching (MPLS) label stack entry: "EXP" field 
   renamed to "Traffic Class" field '
   <draft-ietf-mpls-cosfield-def-08.txt> as a Proposed Standard

This document is the product of the Multiprotocol Label Switching Working 
Group. 

The IESG contact persons are Ross Callon and David Ward.

A URL of this Internet-Draft is:
http://www.ietf.org/internet-drafts/draft-ietf-mpls-cosfield-def-08.txt

Technical Summary

   The early Multiprotocol Label Switching (MPLS) documents defined the
   format of the MPLS Label Stack.  This includes a three bit field
   called the "EXP field".  The exact use of this field was not defined
   by these documents, except to state that it was to be "reserved for
   experimental use".

   Although the intended use of the EXP field was as a "Class of
   Service" (CoS) field, it was not named the CoS field by these early
   documents because the use of such a CoS field was not considered to
   be sufficiently defined.  Today a number of standards documents
   define its usage as a CoS field.

   To avoid misunderstanding about how this field may be used, it has
   become important to rename this field.  This document changes the
   name of the field to the "Traffic Class field" ("TC field".)  In
   doing so it also updates documents that define the current use of
   the EXP field.

Working Group Summary

   Solid consensus (see PROTO writeup by George Swallow). 

Document Quality

   The RFCs that this document references and updates are widely
   implemented and deployed, and use the three bit "EXP" field 
   as a class of service field. Thus the change of name for the 
   field specified in this draft is consistent with widely deployed 
   protocols and equipment (and consistent with the original 
   intended use of this field). 

   There are four informational RFCs (RFC 3272, RFC 3469,
   RFC 3564 and RFC 3985) that are listed as normative 
   references. This is because this document makes manadatory
   changes to these RFCs (by changing the name of one field used
   by these RFCs). These downrefs were mentioned in the IETF 
   last call. 

Personnel

   George Swallow is the document shepherd for this document. Ross
   Callon is the Responsible Area Director. 

RFC Editor Note

   Please update Section 2.2 (entitled "RFC 3270"), paragraph 7 
   (immediately after bullet "a." as follows:

   OLD

       The EXP field has been renamed to the TC field, and thus all
       references in RFC 3270 to EXP field SHOULD be taken to refer
       to the TC field.

   NEW

       The EXP field has been renamed to the TC field, and thus all
       references in RFC 3270 to EXP field now refer to the TC field.

   Please update the same section, approximately paragraph 11 
   (the first paragraph of the updated section 1.2 of RFC3270) 
   as follows:

   OLD

       The EXP field has been renamed to the TC field, and thus all
       references in RFC 3270 to EXP field SHOULD be taken to refer
       to the TC field.  However, we retain the acronym E-LSP
       (Explicitly TC-encoded-PSC LSP) as the acronym is in 
       widespread use.

    NEW

       The EXP field has been renamed to the TC field, and thus all
       references in RFC 3270 to EXP field now refer to the TC field.
       However, we retain the acronym E-LSP (Explicitly 
       TC-encoded-PSC LSP) as the acronym is in widespread use.

   Section 2.3 (entitled "RFC 5129"), please update the third paragraph 
   as follows:

     OLD

       The EXP field has been renamed to the TC field, and thus all
       references in RFC 5129 to EXP field SHOULD be taken to refer to
       the TC field.

     NEW

       The EXP field has been renamed to the TC field, and thus all
       references in RFC 3270 to EXP field now refer to the TC field.

   Please update the first paragraph in section 2.4 as follows:

     OLD

       There are several places in the RFCs that has explicitly
       updated by this document that reference the "Exp field", 
       sometimes they refer to the field as "Exp bits", "EXP bits"
       and "EXP".  In all those instances the references SHOULD be
       taken to reference the TC field.

     NEW

       There are several places in the RFCs that are explicitly
       updated by this document that reference the "Exp field", 
       sometimes they refer to the field as "Exp bits", "EXP bits"
       and "EXP".  In all those instances the references now 
       reference the TC field.

    Please update the following paragraph (second paragraph of section
    2.4), last sentence, as follows:

      OLD

        For all RFCs, including but not limited to those mentioned
        in this paragraph, such references SHOULD be taken to
        reference the TC field.

      NEW

        For all RFCs, including but not limited to those mentioned
        in this paragraph, such references now reference the TC field.

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