Subject: [tsvwg] Suresh Krishnan's No Objection on draft-ietf-tsvwg-le-phb-09: (with COMMENT)

From: Suresh Krishnan <[email-masked]>
Date: Wed, 20 Feb 2019 17:29:07 -0800

Suresh Krishnan has entered the following ballot position for
draft-ietf-tsvwg-le-phb-09: No Objection

When responding, please keep the subject line intact and reply to all
email addresses included in the To and CC lines. (Feel free to cut this
introductory paragraph, however.)

Please refer to https://www.ietf.org/iesg/statement/discuss-criteria.html
for more information about IESG DISCUSS and COMMENT positions.

The document, along with other ballot positions, can be found here:
https://datatracker.ietf.org/doc/draft-ietf-tsvwg-le-phb/

----------------------------------------------------------------------
COMMENT:
----------------------------------------------------------------------

I was not sure how this behavior in Section 8 is expected to be deployed and
used.

"  A DS domain that still uses DSCP CS1 for marking LE traffic
   (including Low Priority-Data as defined in [RFC4594] or the old
   definition in [RFC3662]) SHOULD remark traffic to the LE DSCP
   '000001' at the egress to the next DS domain."

Is the expectation that even on a domain that has not been updated to use the
new DSCP there will be some node at the edge that will have been updated? If
so, it might be good to explicitly note this. If not, I cannot see how a legacy
node will follow this recommendation.

---

From: Brian E Carpenter <[email-masked]>
Date: Thu, 21 Feb 2019 15:16:17 +1300

> https://datatracker.ietf.org/doc/draft-ietf-tsvwg-le-phb/

If the routers involved genuinely follow the diffserv model, in which
any per-hop behavior can be mapped to any codepoint, all these things
will be configurable. So if the operator decides to continue using CS1
internally but conform to the spec externally, they could reconfigure the
edges accordingly. In other words the legacy is in the configuration,
not the code.

Of course if the vendor hard coded the (mis)use of CS1 this can't
work, which I guess is why it's a SHOULD.

   Brian

---

From: Suresh Krishnan <[email-masked]>
Date: Fri, 22 Feb 2019 04:22:46 +0000

> On Feb 20, 2019, at 9:16 PM, Brian E Carpenter <[email-masked]> wrote:
> 

Thanks for the clarification Brian. That makes perfect sense.

Regards
Suresh