RFC 5521, "Extensions to the Path Computation Element Communication Protocol (PCEP) for Route Exclusions", April 2009

Errata ID: 1775
Status: Verified
Type: Technical
Publication Format(s) : TEXT
Reported By: Alfred Hoenes
Date Reported: 2009-05-05
Verifier Name: Adrian Farrel
Date Verified: 2010-01-02

Section 2.1.1, pg. 6 says:

   Type
      The type of the subobject.  The following subobject types are
      defined.

      Type           Subobject
      -------------+-------------------------------
      1              IPv4 prefix
      2              IPv6 prefix
      4              Unnumbered Interface ID
      32             Autonomous system number
      34             SRLG

   Length
      [...]

   Prefix Length
      [...]

   Attribute
      The Attribute field indicates how the exclusion subobject is to be
      interpreted.

   0 Interface
      The subobject is to be interpreted as an interface or set of
      interfaces.  All interfaces identified by the subobject are to be
      excluded from the computed path according to the setting of the
|     X-bit.  This value is valid only for subobject types 1, 2, and 3.

   1 Node
      The subobject is to be interpreted as a node or set of nodes.  All
      nodes identified by the subobject are to be excluded from the
      computed path according to the setting of the X-bit.  This value
|     is valid only for subobject types 1, 2, 3, and 4.

   2 SRLG
      The subobject identifies an SRLG explicitly or indicates all of
      the SRLGs associated with the resource or resources identified by
      the subobject.  Resources that share any SRLG with those
      identified are to be excluded from the computed path according to
      the setting of the X-bit.  This value is valid for all subobjects.

It should say:

   Attribute
      The Attribute field indicates how the exclusion subobject is to be
      interpreted.

   Type
      [...]

   Length
      [...]

   Prefix Length
      [...]

   Attribute
      The Attribute field indicates how the exclusion subobject is to be
      interpreted.

      0 Interface
         The subobject is to be interpreted as an interface or set of
         interfaces.  All interfaces identified by the subobject are to
         be excluded from the computed path according to the setting of
         the X-bit.  This value is valid only for subobject types 1, 2,
|        and 4.
             ^

      1 Node
         The subobject is to be interpreted as a node or set of nodes.  
         All nodes identified by the subobject are to be excluded from
         the computed path according to the setting of the X-bit.  This
|        value is valid only for subobject types 1, 2, 4, and 32.
                                                       ^      ^^

      2 SRLG
         The subobject identifies an SRLG explicitly or indicates all of
         the SRLGs associated with the resource or resources identified
         by the subobject.  Resources that share any SRLG with those
         identified are to be excluded from the computed path according 
         to the setting of the X-bit.  This value is valid for all
         subobjects.

Notes:

Rationale:

a) Technical:
The enumeration of subobject types for Attribute '0 Interface'
and '1 Node' is out of sync with the table at the top of the page
and the IANA registry (cf. Section 4.1 of this RFC, on page 13).

The Corrected Text proposed above is based on the assumption that
the figures given originally refer to the position of the
subobjects in the table, i.e. that the subobjects in the table
once had been assigned sequential type numbers, 1 through 5;
this change seems to be technically reasonable.

>>> Technical change verified by original document author and cross-checked
>>> to early versions of the document.

b) Editorial: For clarity, the details for the Attribute field
values should have been indented one more step, making them
visually subordinate to 'Attribute' and not appearing like
additional common fields.

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