Subject: Protocol Action: Per Hop Behavior Identification Codes to Proposed Standard

From: The IESG <[email-masked]>
Date: Thu, 02 Mar 2000 07:41:04 -0500

The IESG has approved the Internet-Draft 'Per Hop Behavior
Identification Codes' <draft-ietf-diffserv-phbid-00.txt> as a Proposed
Standard.  This document is the product of the Differentiated Services
Working Group.  The IESG contact persons are Scott Bradner and Vern
Paxson.

Technical Summary
 
 Differentiated Services (RFC 2474, RFC 2475]) introduces the notion of
 Per Hop Behaviors (PHBs) that define how traffic belonging to a
 particular behavior aggregate is treated at an individual network
 node. In IP packet headers, PHBs are not indicated as such; instead
 Differentiated Services Codepoint (DSCP) values are used. There are
 only 64 possible DSCP values, but there is no such limit on the
 number of PHBs. In a given network domain, there is a locally defined
 mapping between DSCP values and PHBs. Standardized PHBs recommend a
 DSCP mapping, but network operators may choose alternative mappings.

 In some cases it is necessary or desirable to identify a particular
 PHB in a protocol message, such as a message negotiating bandwidth
 management or path selection, especially when such messages pass
 between management domains. Examples where work is in progress
 include communication between bandwidth brokers, and MPLS support of
 diffserv.

 In certain cases, what needs to be identified is not an individual
 PHB, but a set of PHBs. One example is a set of PHBs that must follow
 the same physical path to prevent re-ordering.  An instance of this
 is the set of three PHBs belonging to a single Assured Forwarding
 class, such as the PHBs AF11, AF12 and AF13 (RFC 2597).

 This document defines a binary encoding to uniquely identify PHBs
 and/or sets of PHBs in protocol messages.

Working Group Summary

 The working group supported the publication of this document.

Protocol Quality

 This document was reviewd for the IESG by Scott Bradner.

Note to RFC Editor:

Please remove the acknowledgments section prior to publication.

Please change the last sentence in the last paragraph of section 1.1 (Usage Scenarios) to:

    To do so the Forum is defining a new VC call setup information
    element which will carry PHB identification codes (although this will
    be generalized to do more if needed).