[tsvwg] COMMENT PLEASE: Which DSCP value should we use for LE PHB?

[Gorry Fairhurst <[e-mail]>]

This email is intended to start a discussion about the most appropriate 
DiffServ codepoint to assign to the LE PHB specified in:
https://tools.ietf.org/html/draft-ietf-tsvwg-le-phb-02

The current list of available codepoints is listed by IANA here:
https://www.iana.org/assignments/dscp-registry/dscp-registry.xhtml

The draft currently suggests using the DSCP value 3, '000010'.

Question 1: Is this codepoint a good choice for the TSVWG group to 
assign for the LE PHB?

   Things to consider:
     - Is the codepoint currently being used for other (non-standard 
applications) that may get in the way of the deployment of the LE PHB?
     - Is there ant evidence that this DSCP value is less likely to be 
forwarded than other unused codepoints?
     - Is this codepoint observed in the wild due to common 
DSCP-mangling pathologies (such as ToS-byte bleaching)?

Question 2: Is there an alternate unassigned codepint that could be 
chosen that would give better opprotunities for deployment?

     Things to consider:
     - A codepoint less than 7 appears to have less chance of 
DSCP-mangling pathologies (such as ToS-byte bleaching)
     - IANA currently allocates from pool 1 (xxxxx0), but we could 
consider asking to use pool 3 ('xxxx01'), e.g., '000001'or '000101'.

Measurement experience and thoughts on this topic are welcome on the 
mailing list ahead of the TSVWG meeting. At this meeting, I would like 
to see some discussion confirming the choice of DSCP codepoint or 
suggesting a more appropriate codepoint for the working group to request.

Gorry Fairhurst
(TSVWG Co-Chair)