Re: [Diffserv] Dscp and DscpOrAny TCs

[John Schnizlein <jschnizl@cisco.com>]

Good catch, Bert.
The idea of a mask for the DSCP was killed some time ago in Policy Framework based on its incompatibility with the following explicit prohibition in the definition of the Differentiated Services Field:

RFC 2474 Section 3, page 7
   Implementors should note that the DSCP field is six bits wide.  DS-
   compliant nodes MUST select PHBs by matching against the entire 6-bit
   DSCP field, e.g., by treating the value of the field as a table index
   which is used to select a particular packet handling mechanism which
   has been implemented in that device.  The value of the CU field MUST
   be ignored by PHB selection.  The DSCP field is defined as an
   unstructured field to facilitate the definition of future per-hop
   behaviors.

John

At 11:36 AM 3/5/2003, Wijnen, Bert (Bert) wrote:
>Do Diffservers think that the following is wise and makes sense?
>
>   docsSubMgtPktFilterDscpValue OBJECT-TYPE
>       SYNTAX      Dscp
>       MAX-ACCESS  read-create
>       STATUS      current
>       DESCRIPTION
>           "The Differentiated Services Code Point (DSCP) value to match
>            in the IP packet."
>       DEFVAL { 0 }
>       ::= { docsSubMgtPktFilterEntry 9 }
>
>   docsSubMgtPktFilterDscpMask OBJECT-TYPE
>       SYNTAX      Dscp
>       MAX-ACCESS  read-create
>       STATUS      current
>       DESCRIPTION
>           "The mask to apply against the DSCP value to be matched in
>       the IP packet.  The default for both these objects taken together
>       matches all DSCP values. A packet matches this filter if the
>       following is true:
>           AND (FilterDscpValue, FilterDscpMask) ==
>           AND (Packet DSCP Value, FilterDscpMask)."
>       DEFVAL { 0 }
>       ::= { docsSubMgtPktFilterEntry 10 }
>
>It is defined in draft-ietf-ipcdn-subscriber-mib-10.txt and I'd like
>to hear comments from Diffserv experts.
>
>Thanks,
>Bert 

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